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Graphene-based nanomaterials in biosystems
Nano Research
Abstract
Graphene-based nanomaterials have emerged as a novel type of materials with exceptional physicochemical properties and numerous applications in various areas. In this review, we summarize recent advances in studying interactions between graphene and biosystems. We first provide a brief introduction on graphene and its derivatives, and then discuss on the toxicology and biocompatibility of graphene, including the extracellular interactions between graphene and biomacromolecules, cellular studies of graphene, and in vivo toxicological effects. Next, we focus on various graphene-based practical applications in antibacterial materials, wound addressing, drug delivery, and water purification. We finally present perspectives on challenges and future developments in these exciting fields.
... The development of nanomaterials in wound care has complemented the use of nanotechnology in drug delivery systems [10,[17][18][19]. Nanomaterials are one of the most widely used materials in wound care to address the complexities of the normal wound healing cycle, cell-type specificity, a surplus of regulating molecules, and chronic wound pathophysiology [11,20]. ...
... Because of their large surface area and chemical and physical properties, graphene-based nanoparticles are excellent candidates for use as nanoscale building blocks in biological research [89]. Strong van der Waals attractions between the molecules are very helpful in designing nanocomposites [18]. ...
... These composites are prepared mainly by chemical reduction, microwave-assisted growth, solution mixing, and hydrothermal methods. Graphene can also be incorporated into dressings along with silver oxide (AgO), zinc oxide (ZnO), and copper oxide (CuO), or as Ag-graphene polymer hydrogel for rapid wound healing [18,87] Secondary infections can occur as a result of microbial attack after skin injury. Commercially available wound dressings are required in the early stages of injury, but they have the disadvantage of quickly adhering to the wound surface and causing trauma to the healing injury. ...
Wound healing is a complex process that can be further complicated in chronic wounds, leading to prolonged healing times, high healthcare costs, and potential patient morbidity. Nanotechnology has shown great promise in developing advanced wound dressings that promote wound healing and prevent infection. The review article presents a comprehensive search strategy that was applied to four databases, namely Scopus, Web of Science, PubMed, and Google Scholar, using specific keywords and inclusion/exclusion criteria to select a representative sample of 164 research articles published between 2001 and 2023. This review article provides an updated overview of the different types of nanomaterials used in wound dressings, including nanofibers, nanocomposites, silver-based nanoparticles, lipid nanoparticles, and polymeric nanoparticles. Several recent studies have shown the potential benefits of using nanomaterials in wound care, including the use of hydrogel/nano silver-based dressings in treating diabetic foot wounds, the use of copper oxide-infused dressings in difficult-to-treat wounds, and the use of chitosan nanofiber mats in burn dressings. Overall, developing nanomaterials in wound care has complemented nanotechnology in drug delivery systems, providing biocompatible and biodegradable nanomaterials that enhance wound healing and provide sustained drug release. Wound dressings are an effective and convenient method of wound care that can prevent wound contamination, support the injured area, control hemorrhaging, and reduce pain and inflammation. This review article provides valuable insights into the potential role of individual nanoformulations used in wound dressings in promoting wound healing and preventing infections, and serves as an excellent resource for clinicians, researchers, and patients seeking improved healing outcomes.
... Tere are several members in the family, with the most notable being Graphene Oxide (GO), Reduced Graphene Oxide (rGO), Graphene quantum dots (GQD), and Graphene Nanoribbons (GNR) [25]. In addition, their characteristics, including their sizable surface area, high loading capacity, highly desirable thermal and mechanical properties, pH responsiveness, and capable enhanced permeability and retention (EPR) efects, have been well described in the literature [25][26][27]. Teir toxic efects have also been investigated on C. elegans worms and Zebrafsh, but the results were not as straightforward, with signifcant toxicity shown to the former but no adverse efects on the latter [28,29]. In addition, their efects on human cells are not yet fully comprehended, with studies reporting negligible to signifcant toxic efects based on the utilized nanocomponent's size, coating, and structure [26]. ...
... Teir toxic efects have also been investigated on C. elegans worms and Zebrafsh, but the results were not as straightforward, with signifcant toxicity shown to the former but no adverse efects on the latter [28,29]. In addition, their efects on human cells are not yet fully comprehended, with studies reporting negligible to signifcant toxic efects based on the utilized nanocomponent's size, coating, and structure [26]. ...
Objectives. Due to Albendazole’s relatively low efficacy and bioavailability, Echinococcosis has proven a challenge to manage successfully, with several studies investigating ways to improve the outcome, mainly showing mixed results. We, therefore, aimed to evaluate whether Sulfonated Graphene Oxide (S-GO), as nanocarriers, could improve the mentioned outcome. Methods. Echinococcus protoscoleces were divided into four groups based on the agent they received, which comprised control, S-GO, Albendazole, and Albendazole-loaded S-GO (S-GO-Albendazole). Then, the Bax and Bcl-2 gene expression levels and the number of surviving protoscoleces in each group were determined. Results. Bax gene expression increased by 121% in the 50 μg/ml concentration of the S-GO-Albendazole, while Bcl-2 gene expression decreased by 64%. Moreover, S-GO-Albendazole was approximately 18% more effective at neutralizing protoscoleces than Albendazole and 14% and 31% more effective at improving the expression of the mentioned genes, respectively (p<0.05). In addition, the number of surviving protoscoleces after exposure to the mentioned concentration reduced by approximately 99%. Conclusions. S-GO, despite not having significant lethality on protoscoleces, significantly increased the lethality of Albendazole and, therefore, is a suitable nanocarrier. However, we recommend conducting in vivo and clinical studies to more accurately determine this nanocomplex’s potential and side effects.
... Graphene-zinc oxide composite is obtained as a result of depositing zinc (II) ions or zinc oxide nanoparticles on graphene nanosheet surfaces. This composite exhibits superior antimicrobial effects [85,86]. The titanium dioxide (TiO2) nanoparticle shows good antimicrobial properties when used with graphene oxide. ...
... In addition, the scaffold has a highly porous structure. The highly porous structure allows to adhere of cell and to proliferate it [86]. ...
... Graphene-based nanoparticles have developed as a new category of materials with exceptional physicochemical properties and a broad range of applications. Recent advancements in graphene-biosystem interactions research indicate that they have the potential to be used in a wide range of applications, from antibacterial materials to drug delivery [76]. ...
... Graphene is a renewable material that is simple to produce using low-cost and quick-preparation procedures. Graphene has been employed in a variety of conceptual and technological applications, such as antimicrobial materials, cell culture substrates, biosensors, and therapeutics carriers (Fig. 4) [76]. ...
About book:
Bio-Inspired Nanotechnology focuses on the use of bio-inspired and biomimetic methods for the fabrication and activation of nanomaterials. It summarizes recent developments in biocompatible and biodegradable materials, including their properties, fabrication methods, synthesis protocols, and applications. This includes studies concerning the binding of the biomolecules to the surface of inorganic structures, structure/function relationships of the final materials, and unique applications of such biomimetic materials in harvesting/storage, biomedical diagnostics, and materials assembly. The book chapters also cover a range of available bio-based nanomaterials, including chitin, starch and nanocellulose. It serves as a detailed reference for learners and anyone interested in sustainable nanoscale materials, including materials scientists, biomedical engineers, environmental scientists, food and agriculture manufacturers and scientists.
... Graphene-zinc oxide composite is obtained as a result of depositing zinc (II) ions or zinc oxide nanoparticles on graphene nanosheet surfaces. This composite exhibits superior antimicrobial effects [85,86]. The titanium dioxide (TiO2) nanoparticle shows good antimicrobial properties when used with graphene oxide. ...
... In addition, the scaffold has a highly porous structure. The highly porous structure allows to adhere of cell and to proliferate it [86]. ...
... Graphene and graphene oxide, distinguished by their significant theoretical surface areas, have emerged as noteworthy adsorbents, demonstrating remarkable effectiveness in the exclusion of heavy metals and other toxins (Wang et al. 2021;Lu et al. 2019;Al-Mhyawi et al. 2023;Atia et al. 2019;Abdalla 2024;Gado 2024;Gado et al. 2020). ...
A novel composite material composed of polyvinyl alcohol and L-2-Amino-3-mercaptopropionic Acid has been developed to efficiently remove heavy metals namely; mercury, chromium, lead and cadmium from industrial wastewater. The composite structure was confirmed via a variety of analytical techniques, ensuring its structural, chemical, and physical stability. Under optimized conditions-room temperature, a pH range of 4 to 5.5, a contact time of 15 to 20 min, and with a metal ion concentration of 200 mg/L. The composite exhibited impressive adsorption capacities: 49.6 mg/g for Hg(II), 26 mg/g for Cr(III), 47.25 mg/g for Pb, and 45.25 mg/g for Cd(II). The uptake behavior followed the Langmuir isotherm model, with theoretical maximum uptake values closely matching experimental results: 49.25 mg/g for Hg(II), 26.88 mg/g for Cr(III), 48.63 mg/g for Pb(II), and 45.75 mg/g for Cd(II). Kinetic studies indicated that the adsorption process adhered to a pseudo-first-order model, suggesting rapid and efficient uptake. Thermodynamic analysis indicated that the adsorption process was spontaneous , exothermic, and became more favorable at lower temperatures. The composite demonstrated reusability, with metal ions being effectively desorbed using 1 M HNO 3 , enabling regeneration and reuse. Additionally, the treated wastewater met the World Health Organization and Food and Agriculture Organization guidelines for safe discharge into marine environments. Editorial responsibility:
... In the beginning, high-purity Ar gas was continuously pumped into a graphiteresistant vacuum furnace to heat dried flower petals. A noticeably thick, dark green solution was produced when these petals were placed between two graphite plates in the furnace with a top loading of 150 g (Lu et al., 2019;Teixeira et al., 1998a). This thick slurry formed as a result of the lengthy reaction time under constant stirring and heating. ...
... Chemists and material scientists are now endeavoring to imitate natural antioxidases to create new biocatalytic materials for various antioxidant therapeutic purposes [23][24][25][26][27] . Recently, polyphenol nanoparticles [28][29][30] , nanocarbons 31,32 , metal oxides 22,33,34 , etc., have been intensively developed into antioxidant nanostructures for ROS clearance and tissue regeneration therapies, especially creating metal oxides for biocatalytic therapeutics. Among diverse metal oxides, cerium oxide (CeO 2 ) has been reported to exhibit excellent biostability, biocompatibility, and a certain degree of antioxidase-like properties and can be fabricated into bone scaffolds with high mechanical strength [35][36][37][38][39][40] . ...
The clinical treatments of maxillofacial bone defects pose significant challenges due to complex microenvironments, including severe inflammation, high levels of reactive oxygen species (ROS), and potential bacterial infection. Herein, we propose the de novo design of an efficient, versatile, and precise electron-donable heterojunction with synergetic Ru-Cu pair sites (Ru-Cu/EDHJ) for superior biocatalytic regeneration of inflammatory mandible defects and pH-controlled antibacterial therapies. Our studies demonstrate that the unique structure of Ru-Cu/EDHJ enhances the electron density of Ru atoms and optimizes the binding strength of oxygen species, thus improving enzyme-like catalytic performance. Strikingly, this biocompatible Ru-Cu/EDHJ can efficiently switch between ROS scavenging in neutral media and ROS generation in acidic media, thus simultaneously exhibiting superior repair functions and bioadaptive antibacterial properties in treating mandible defects in male mice. We believe synthesizing such biocatalytic heterojunctions with exceptional enzyme-like capabilities will offer a promising pathway for engineering ROS biocatalytic materials to treat trauma, tumors, or infection-caused maxillofacial bone defects.
... GP, a 2D structure, is where every single atom is exposed to a chemical reaction from either side [14]. GO, obtained from the oxidation of GP, contains epoxy and carbon radicals in the basal planes, with carboxyl and hydroxyl groups on its edges [15]. Also, GO has more hydrophilic groups and easy dispersion ability [16]. ...
Background
Bone defects, especially critical-size bone defects, and their repair pose a treatment challenge. Osteoinductive scaffolds have gained importance given their potential in bone tissue engineering applications.
Methods
Polycaprolactone (PCL) scaffolds are used for their morphological, physical, cell-compatible and osteoinductive properties. The PCL scaffolds were prepared by electrospinning, and the surface was modified by layer-by-layer deposition using either graphene or graphene oxide.
Results
Graphene oxide-coated PCL (PCL-GO) scaffolds showed a trend for enhanced physical properties such as fibre diameter, wettability and mechanical properties, yield strength, and tensile strength, compared to graphene-modified PCL scaffolds (PCL-GP). However, the surface roughness of PCL-GP scaffolds showed a higher trend than PCL-GO scaffolds. In vitro studies showed that both scaffolds were cell-compatible. Graphene oxide on PCL scaffold showed a trend for enhanced osteogenic differentiation of human umbilical cord Wharton’s jelly-derived Mesenchymal Stem Cells without any differentiation media than graphene on PCL scaffolds after 21 days.
Conclusion
Graphene oxide showed a trend for higher mineralisation, but this trend is not statistically significant. Therefore, graphene and graphene oxide have the potential for bone regeneration and tissue engineering applications. Future in vivo studies and clinical trials are warranted to justify their ultimate clinical use.
Graphical abstract
... Graphene and graphene oxide, distinguished by their significant theoretical surface areas, have emerged as noteworthy adsorbents, demonstrating remarkable effectiveness in the exclusion of heavy metals and other toxins [32][33][34][35] Biochar, generated as a carbon-rich byproduct through the pyrolysis of biomass in an inert atmosphere, has garnered extensive attention in research for its efficacy in removing a spectrum of heavy metals, including Cu, Zn, Mn, Cr, Fe, Pb, Cd, Ni, and Co. This efficacy has been observed across a varied extent of concentrations (1-1000 mg.L À 1 ) when utilized as an adsorbent composite, showcasing an appreciable uptake capacity. ...
A facilely prepared composite based on Polyvinyl alcohol anchored‐ L‐cysteine (PVA‐L‐CYS) demonstrated efficient functionality in the elimination of heavy metals (Hg, Cr, Pb, and Cd) from working wastewater. The synthesis of the composite was validated through a comprehensive characterization utilizing various analytical techniques to ensure the composite‘s structural, chemical, and physical properties. At ambient temperature, pH of 4–5.5, interaction time of 15–20 minutes, and concentration of 200 mg/L metal ions, the composite exhibited a maximum retention capacity of 48.5, 25, 45.25, and 44.25 mg/g for Hg, Cr, Pb, and Cd, respectively. Langmuir modeling was establish to be more fitting to the practical results than Freundlich, providing theoretical values of 49.02, 25.97, 46.08, and 44.84 mg/g for Hg, Cr, Pb, and Cd, respectively. The kinetics of PVA‐L‐CYS composite was accurately predicted by model of the pseudo‐first‐order kinetic. Thermodynamic prospects indicated a spontaneous, exothermic, and favorable uptake process at low temperatures. Efficient elution of the heavy metal ions from the overloaded composite was performed using 1 M HNO3. In accordance with WHO and FAO guidelines, the successful elimination of working metal ions from wastewater utilizing the PVA‐L‐CYS composite was demonstrated in a single cycle before discharge into the marine environment.
... The discovery of graphene created a sensation across the world, as it is the first 2D material with a wide range of applications in various fields [27,28]. Graphene is a 2D carbon nanomaterial composed of a fused benzene ring-like structure arranged in a layered fashion [29]. Graphene has broad applications in display screens, sensors, new energy materials, photosensitive elements, and so on. ...
... Therefore, it can be inferred that the PUCNTs/Zn composites possess a high cytocompatibility. Generally, the graphite or CNTs are considered to be toxic to our bodies at somewhat, which depends on the concentration, size and oxygen content of the graphite or CNTs [35][36][37][38][39][40][41][42]. The more the oxygen content in the graphite or CNTs is, the lower the toxicity is [39,42]. ...
Zn with a suitable degradation rate is considered to be a promising candidate biodegradable implant materials. To enhance the mechanical properties of pure Zn and broaden its application in the field of short-term orthopedic surgery, a series of new Zn matrix composites with a high strength are developed by the addition of partially unzipped carbon nanotubes (PUCNTs), and the degradation behavior, cytotoxicity and hemolysis of new PUCNTs/Zn composites are investigated in this paper. The results show that the degradation rate of the PUCNTs/Zn composites with 0, 0.1, 0.2, 0.3 and 0.5 wt.% PUCNTs can meet the standard of clinical biomedical orthopedic implant materials. During cytotoxicity test, the density of living cells rapidly increases with increasing PUCNTs content, and the cell viability of MG-63 cells in the extract with different concentrations is higher than 90%, illustrating an excellent cytocompatibility. For the hematotoxicity assay, the hemolysis percentage of all PUCNTs/Zn composites samples is below the safety threshold of 5.0% for clinical application, exhibiting a good blood compatibility.
... commercialise the material for a multitude of applications ranging from electronics and optoelectronics, [6] detection and sensing devices, [7,8] biosystems, [9] through to chemical and environmental corrosion inhibition. [10] Currently, graphene nanoplatelets (GNPs) can be produced in large quantities using various bottom-up and top-down methods. ...
X-ray photoelectron spectroscopy (XPS) is widely used for characterising the chemistry of graphene-related two-dimensional materials (GR2M), however the careful preparation of the sample for analysis is important in obtaining representative quantifications. We report an investigation by three laboratories showing that the preparation method for oxygen-functionalised graphene nanoplatelet (GNP) powders has a significant effect on the homogeneous-equivalent elemental composition measured in XPS. We show that pressing GNP powders onto adhesive tapes, into recesses, or into solid pellets results in inconsistencies in the XPS quantification. The measured oxygen-to-carbon atomic ratio from GNP pellets depends upon the die pressure used to form them and the morphology of the GNPs themselves. We recommend that powder samples of GR2Ms are pelletised prior to XPS analysis to improve repeatability and reproducibility of measurements.
... Graphene-based nanomaterials are envisaged as a class of magic materials because of their unique structure and excellent mechanical, optical, and electrical properties [16][17][18]. For instance, their large surface area, covalent, and noncovalent binding capacities of biomolecules, polymers, and organic drug molecules make graphene-based nanomaterials ideal matrices for adsorption and conjugation in the fields of biosensor [19], drug delivery [20], and biomedicine [21]. ...
Diagnostic blood cell counting is of limited use in monitoring a minimal number of leukaemia cells, warranting further research to develop more sensitive and reliable techniques to identify leukaemia cells in circulation. In this work, a hemin–graphene nanocomposite-based aptasensor was developed for ultrasensitive colorimetric detection of leukaemia cells (CEM) using magnetic enrichment. Hemin-conjugated graphene oxide nanocomposites (HGNs) were prepared by hydrazine reduction using graphene oxide nanosheets and hemins. Hence, the prepared HGNs become able to absorb single-stranded DNA and acquire peroxidase-like activity. The aptamer sgc8c, which recognizes a specific target on leukaemia cells, was absorbed onto HGNs to capture the target CEM cancer cells. The captured target cells that associated with the HGNs were then concentrated and separated by magnetic beads (MBs) coated with sgc8c aptamers, forming a HGN–cell–MB sandwich structure. These sandwich structures can be quantified via an oxidation reaction catalysed by HGNs. By utilizing dual signal amplification effects generated by magnetic enrichment and the improved peroxidase activity of HGNs, the biosensor allowed for highly sensitive detection of 10 to 105 CEM cells with an ultra-low limit of detection (LOD) of 10 cells under optimal conditions. It is expected that the proposed aptasensor can be further employed in monitoring the minimal residual disease during the treatment of leukaemia.
... However, most nanoparticles have inferior biocompatibility and are unfavorable for cell growth 25 . As one of the graphene-based nanomaterials, reduced graphene oxide (rGO) has recently emerged as a potential drug carries for various diseases due to its favorable biocompatibility and unique tunable physicochemical properties, such as extremely large surface area, modifiable active groups, etc 26,27 . The π-π conjugate system on a hydrophobic flat region of rGO makes it easy to load genes, chemical drugs, and other molecules 28 . ...
Excessive reactive oxygen species (ROS) are one of the leading mechanisms in the initiation and development of osteoarthritis (OA). However, conventional injection of ROS-responsive drug delivery systems (DDSs) such as nanoparticles and hydrogels usually cannot provide effective treatment due to rapid clearance and degradation or low bioavailability. In this study, a ROS-responsive nanofiber membrane named PLA/PEGDA-EDT@rGO-Fucoxanthin (PPGF) is fabricated by electrospinning, wherein PEGDA-EDT served as the ROS-responsive motif, reduced graphene oxide (rGO) as the drug carrier and fucoxanthin (Fx) as the antioxidative and anti-inflammatory agent. The results demonstrated that the PPGF nanofiber membrane exhibited sustained and long-term Fx release behavior (at least 66 days) in response to hydrogen peroxide (H 2 O 2 ) in vitro. With low cytotoxicity and smart ROS responsiveness, PPGF showed excellent anti-inflammatory and antioxidative effects on IL-1β-induced chondrocytes by potent ROS scavenging potential and upregulation of antioxidative enzymes. It also demonstrated the attenuation of OA progression with the reduced Osteoarthritis Research Society International (OARSI) score by 93.17% in 8 weeks. The smart ROS-responsive, biodegradable and biocompatible nanofiber membranes possess great potential for OA therapy under arthroscopy.
... In addition to inhibiting growth, graphene also disrupts photosynthesis. Furthermore, it leads to an imbalance of nutritional homeostasis, which is manifested by reduced shoot biomass and root hair numbers, reduced chlorophyll content and PSII activity, and nutrient deficiency [108]. From the above results, it can be understood that graphene's physical and chemical properties, like the surface functional groups, fillers, coatings, size and structural defects, can affect its behaviour in vitro/in vivo and its toxicity to biological systems. ...
Nanotechnology is an arena of exploration and innovation concerned with building things generally, advancing resources and devices based on highly specific and superior nanomaterials with unmatched properties dependent on their morphology and diameter. 2D materials such as graphene have unique properties and applications varying from imaging, delivery of drugs, and theranostics of diseases. Each 2D material, ranging from the graphene family, MXenes, chalcogenides, and 2D oxides, have a unique potential based on their shape and morphology. In addition, 2D materials have intriguing physiochemical characteristics, increased aspect ratio and associated increased reactivity that make them an ideal contender in multiple applications. This review aims to answer the existing knowledge gaps in various 2D materials having interdisciplinary roles. We have presented a brief overview of the 2D materials, followed by their synthesis methods and techniques. We have also highlighted the different characterization methods used to characterise various 2D materials. Next, we performed an in-depth analysis of the potential toxicities of 2D materials to assess their risks in multiple applications. Lastly, we conclude our review by presenting the challenges and future perspectives of 2D materials as promising forerunners of science and technology.
... Biochemical research has shown that deoxyribonucleic acid or DNA plays a very important role in the body of living organisms and the transmission of hereditary codes that are required for the synthesis of all enzymes, proteins and affect cell function. It is found that DNA is the first target for the interaction of various therapeutic drugs, including antibiotics and anti-cancer drugs (Lu et al., 2019;Mirzaei Babolghani & Mohammadi-Manesh, 2019;. The mechanism of action of various anticancer drugs with DNA showed that there are two types of interactions between drugs with DNA, including covalent interactions and non-covalent interactions, this property is related to their therapeutic efficacy and mechanism of action of drug (Hisaki et al., 2018;Li et al., 2012;Yin et al., 2018). ...
In this study, the interaction of 5-fluorouracil (5FU) drug with adenine (A), guanine(G), cytosine(C), uracil (U), and thymine (T) nucleobases of DNA and RNA are surveyed at the ωB97XD/LANL2DZ, M06-2X/6-31G (d, p), MPW1PWQ1/6-31G(d, p), PBEPBE/6-31(d, p) and ωB97XD/6-31G(d, p) levels of density functional theory (DFT). The considered complexes of 5FU drug with nucleobases are optimized at the above level of theories. Max Force and RMS of optimization criteria are 0.00035 (Ha), and 0.0003 respectively. From optimized structures, the adsorption energy, thermodynamic parameters in gas and solvent media, quantum theory atom in molecule (QTAIM), electron localized function (ELF), and reduced density gradient (RDG) are calculated at ωB97XD/LANL2DZ and M06-2X/6-31G (d, p) level of DFT theory. The QTAIM, ELF, and RDG results confirm that the nature of bonding between 5FU drug with A, C, G, U, and T nucleobases is electrostatic or hydrogen bond type. The adsorption and thermodynamic energy results demonstrate that the interaction of the 5FU drug with C and G nucleobases is stronger than other nucleobases. The results of this study can be suggested the mechanism of interaction of the 5FU drug with nucleobases of DNA and RNA.
Communicated by Ramaswamy H. Sarma
... We omit the studies of GFET biosensors based on rGO as they are covered extensively elsewhere. 24,25,[34][35][36] We adhere to the principles of achieving better electrical conductivity and low detection limits, dedicate to summarizing the research on the preparation of FET biosensors based on high-quality graphene. ...
Biosensors for quick diagnosis and in situ monitoring are increasingly needed in health care. Field-effect transistor based biosensors have attracted much attention due to their high sensitivity and compatibility with point-of-care applications. As the most important 2D material, graphene has been investigated intensively as a channel material for transistor-based sensors due to its easily enhanced selectivity by rather simple functionalization. However, in order to realize its practical applications, challenges still remain, such as device stability and reproducibility. Here, we review recent progress in the general design strategy of high-performance graphene field-effect transistor biosensors with emphasis on the device physics, defects, Debye screening, and functionalization. Finally, both current applications and perspectives on future development are given.
... Different regulated metabolic pathways under Cu(OH) 2 nanopesticides environment were revealed in cucumber and maize (Zhao et al., 2017). Some work also has suggested nanoparticles (NPs) of metal or metal oxide can enhance the content of reactive oxygen species (ROS) and induce lipid peroxidation, resulting in damage to the cell membrane and cell cycle arrest (Qian et al., 2013;Lu et al., 2019). Crops provide a major route of pollutant exposure to animals and humans, as they serve as the initial stage of the food chain (Gardea-Torresdey et al., 2014). ...
Although the widespread use of nanoparticles has been reported in various fields, the toxic mechanisms of molecular regulation involved in the alfalfa treated by nanomaterials is still in the preliminary research stage. In this study, Bara 310SC (Bara, tolerant genotype) and Gold Empress (Gold, susceptible genotype) were used to investigate how the leaves of alfalfa interpret the physiological responses to graphene stress based on metabolome and transcriptome characterizations. Herein, graphene at different concentrations (0, 1% and 2%, w/w) were selected as the analytes. Physiological results showed antioxidant defence system and photosynthesis was significantly disturbed under high environmental concentration of graphene. With Ultra high performance liquid chromatography electrospray tandem mass spectrometry (UPLC-ESI-MS/MS), 406 metabolites were detected and 62/13 and 110/58 metabolites significantly changed in the leaves of Gold/Bara under the 1% and 2%-graphene treatments (w/w), respectively. The most important metabolites which were accumulated under graphene stress includes amino acids, flavonoids, organic acids and sugars. Transcriptomic analysis reveals 1125 of core graphene-responsive genes in alfalfa that was robustly differently expressed in both genotypes. And differential expression genes (DEGs) potentially related to photosynthetic enzymes, antioxidant enzymes, amino acids metabolism, and sucrose and starch metabolic which finding was supported by the metabolome study. Gold was more disturbed by graphene stress at both transcriptional and metabolic levels, since more stress-responsive genes/metabolites were identified in Gold. A comprehensive analysis of transcriptomic and metabolomic data highlights the important role of amino acid metabolism and nicotinate and nicotinamide metabolism pathways for graphene tolerance in alfalfa. Our study provide necessary information for better understanding the phytotoxicity molecular mechanism underlying nanomaterials tolerance of plant.
... Graphene oxide-based nanoparticles have attracted extensive interests due to their distinct characteristics, such as high stability amphiprotic, and high encapsulation capacity of drugs (Ma et al. 2020a, b, c). Polymer-functionalized graphene oxide nanoparticles and GO-metal nanoparticles are well-recognized types (Lu et al. 2019). Polymer-functionalized graphene oxide nanoparticles can be divided into two categories, one is modified with natural polymers such as CS, hypocrellin A (HA), the other is modified with PEG, poly-ethylenimine (PEI), polyacrylic acid (PAA), and other synthetic polymers. ...
Background
In the last decade, graphene oxide-based nanomaterials, such as graphene oxide (GO) and reduced graphene oxide (rGO), have attracted more and more attention in the field of biomedicine. Due to the versatile surface functionalization, ultra-high surface area, and excellent biocompatibility of graphene oxide-based nanomaterials, which hold better promise for potential applications than among other nanomaterials in biomedical fields including drug/gene delivery, biomolecules detection, tissue engineering, especially in cancer treatment.
Results
Here, we review the recent progress of graphene oxide-based multifunctional nanomaterials for cancer treatment. A comprehensive and in-depth depiction of unique property of graphene oxide-based multifunctional nanomaterials is first interpreted, with particular descriptions about the suitability for applying in cancer therapy. Afterward, recently emerging representative applications of graphene oxide-based multifunctional nanomaterials in antitumor therapy, including as an ideal carrier for drugs/genes, phototherapy, and bioimaging, are systematically summarized. Then, the biosafety of the graphene oxide-based multifunctional nanomaterials is reviewed.
Conclusions
Finally, the conclusions and perspectives on further advancing the graphene oxide-based multifunctional nanomaterials toward potential and versatile development for fundamental researches and nanomedicine are proposed.
Graphic abstract
... [1,2] Recently, with the rapid advance in biotechnology and nanotechnology, DNA-functionalized nanomaterials, such as DNA/GO, [3] DNA/Au, [4] and DNA/MFe 2 O 4 , [5] exhibit extensively development as new applications of DNA in biosensors, [3,6,7] biomedicine, [8,9] nanotechnology, [10] and materials science. [11][12][13] Among these applications, the combination of DNA and graphene, the first two-dimensional (2D) atomic crystal available to us, attracts a great deal of interest. Graphene exhibits many extraordinary properties, such as high surface area, [14] fast electron mobility, [15] good optical transparency, [16,17] high Young's modulus, [18] and excellent thermal conductivity, [19] which can be exploited for numerous applications in energy, environment, [20] and biomedicine. ...
DNA/GO composite plays a significant role in the research field of biotechnology and nanotechnology, and attracts a great deal of interest. However, it is still unclear how the oxidation degree of the graphene-based surface affects the adsorption process of single-strand DNA (ssDNA). In this paper, based on the molecular dynamics simulations, we find that ssDNA molecule is absorbed on the GO surface in the most stable state with the oxidation degree around 15%. The microscopic mechanism is attributed to the van Der Walls and the electrostatic interactions between the ssDNA molecule and the graphene-based surface, which is accompanied with the π–π stacking and hydrogen bond formation. The number of π–π stacking between ssDNA and GO reaches the maximum value when the oxidation degree is around 15% among all the GO surfaces. Our simulation results also reveal the coexistence of stretched and curved configurations as well as the adsorption orientation of ssDNA on the GO surface. Furthermore, it is found that the absorbed ssDNA molecules are more likely to move on the graphene-based surface of low oxidation degree, especially on pristine graphene. Our work provides the physics picture of ssDNA’s physisorption dynamics onto graphene-based surface and it is helpful in designing DNA/GO nanomaterials.
Trimetallic nanoparticles (TMNPs) have emerged as a pivotal area of research due to their unique properties and diverse applications across medicine, agriculture, and environmental sciences. This review provides several novel contributions that distinguish it from existing literature on trimetallic nanoparticles (TMNPs). Firstly, it offers a focused exploration of TMNPs, specifically addressing their unique properties and applications, which have been less examined compared to other multimetallic nanoparticles. This targeted analysis fills a significant gap in current research. Secondly, the review emphasizes innovative biosynthesis methods utilizing microorganisms and plant extracts, positioning these green synthesis approaches as environmentally friendly alternatives to traditional chemical methods. This focus aligns with the increasing demand for sustainable practices in nanotechnology. Furthermore, the review integrates discussions on both medical and agricultural applications of TMNPs, highlighting their multifunctional potential across diverse fields. This comprehensive perspective enhances our understanding of how TMNPs can address various challenges. Additionally, the review explores the synergistic effects among the different metals in TMNPs, providing insights into how these interactions can be harnessed to optimize their properties for specific applications. Such discussions are often overlooked in existing studies. Moreover, this review identifies critical research gaps and challenges within the field, outlining future directions that encourage further investigation and innovation in TMNP development. By doing so, it proactively contributes to advancing the field. Finally, the review advocates for interdisciplinary collaboration among material scientists, biologists, and environmental scientists, emphasizing the importance of diverse expertise in enhancing the research and application of TMNPs.
Glioblastoma multiforme (GBM) is the most fatal brain tumor with a poor prognosis with current treatments, mainly because of intrinsic resistance processes. GBM is also referred to as grade 4 astrocytoma, that makes up about 15.4 % of brain cancers globally as well as 60–75 % of astrocytoma. The most prevalent therapeutic choices for GBM comprise surgery in combination with radiotherapy and chemotherapy, providing patients with an average survival of 6–14 months. Nanocarriers provide various benefits such as enhanced drug solubility, biocompatibility, targeted activity, as well as minimized side effects. In addition, GBM treatment comes with several challenges such as the presence of the blood–brain barrier (BBB), blood–brain tumor barrier (BBTB), overexpressed efflux pumps, infiltration, invasion, drug resistance, as well as immune escape due to tumor microenvironment (TME) and cancer stem cells (CSC). Recent research has focused on nanocarriers due to their ability to self-assemble, improve bioavailability, provide controlled release, and penetrate the BBB. These nano-based components could potentially enhance drug accumulation in brain tumor tissues and reduce systemic toxicity, making them a compelling solution for GBM therapy. This review captures the complexities associated with multi-functional nano drug delivery systems (NDDS) in crossing the blood–brain barrier (BBB) and targeting cancer cells. In addition, it presents a succinct overview of various types of targeted multi-functional nano drug delivery system (NDDS) which has exhibited promising value for improving drug delivery to the brain.
The modern nanomedicine incorporates the multimodal treatments into a single formulation, offering innovative cancer therapy options. Nanosheets function as carriers, altering the solubility, biodistribution, and effectiveness of medicinal compounds, resulting in more efficient cancer treatments and reduced side effects. The non‐toxic nature of fluorinated graphene oxide (FGO) nanosheets and their potential applications in medication delivery, medical diagnostics, and biomedicine distinguish them from others. Leveraging the unique properties of Lissachatina fulica snail mucus ( Lf SM), FGO nanosheets were developed to reveal the novel characteristics. Consequently, Lf SM was utilized to create non‐toxic, environmentally friendly, and long‐lasting FGO nanosheets. Ultraviolet–visible (UV–vis) spectroscopy revealed a prominent absorbance peak at 235 nm. The characterization of the synthesized FGO nanosheets involved X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), high‐resolution transmission electron microscopy (HR‐TEM), and atomic force microscopy (AFM) analyses. The antimicrobial activity data demonstrated a broad spectrum of antibacterial effects against Escherichia coli , Bacillus subtilis , Klebsiella pneumoniae , and Pseudomonas aeruginosa . The cytotoxicity efficacy of Lf SM‐FGO nanosheets against pancreatic cancer cell line (PANC1) showed promising results at low concentrations. The study suggests that FGO nanosheets made from Lf SM could serve as alternate factors for in biomedical applications in the future.
Parkinson's disease (PD) is a progressive, complex, and chronic neurodegenerative disorder that remains challenging to cure and diagnose in the early stage. The neuropathological hallmark of PD are Lewy bodies, which are intracellular protein aggregates composed primarily of α-synuclein (α-syn). The unmet therapeutic and diagnostic needs are projected to be managed by exploring alternative strategies. In this direction, research on using tailored graphene-based nanomaterials (GBNs) is gaining attention due to their capability to affect pathogenic forms of α-syn. In this review, we discuss computational and experimental approaches and look at the benefits of GBNs to target mechanisms contributed to PD neurodegeneration, including α-syn aggregation, autophagy, inflammation, and oxidative stress, for the development of an entirely new class of antiparkinsonian therapy. We overview advanced GBN-based nanomedicines, regenerative medicine, and biosensors supporting the application of GBNs in PD management. Moreover, this review highlights the biocompatibility and safety aspects of emergent GBNs. Although GBNs represent a new and promising approach to PD treatment, as of now, it is limited to computational and early-stage experimental studies, as carefully discussed in this article.
2-Methacryloyloxyethyl phosphorylcholine (MPC) zwitterions were modified onto self-made graphene oxide (GO) through the atom transfer radical polymerization method. The chemical structures of the products were verified using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, nuclear magnetic resonance spectroscopy (NMR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), etc. It was found that the modified GO (GO-PCn) is well dispersed in water with an average hydrodynamic diameter of about 170 nm. By utilizing the 2D planar structure of this modified graphene, the irinotecan@GO-PCn composite can be loaded with about 20% of irinotecan via π–π stacking interaction and exhibit pH-sensitive drug release performance, releasing faster in the acidic environment. The in vitro cytotoxicity assessments confirmed that GO-PCn composed of phosphorylcholine moiety represented low cytotoxicity and acted as a certain effect on reducing the acute toxicity of irinotecan, which established a foundation for further studies of the system in oncology therapy.
Abstract Since its isolation, graphene has received growing attention from academia and industry due to its unique properties. However, the “what is my material” barrier hinders further commercialization. X‐ray photoelectron spectroscopy (XPS) is considered as a method of choice for the determination of the elemental and chemical composition. In this work the influence of the morphology of graphene particles on the XPS results is studied and investigated as a function of X‐ray energy, using conventional XPS with Al Kα radiation and hard X‐ray photoemission spectroscopy (HAXPES) using Cr Kα radiation. Thereby, the information depth is varied between 10 and 30 nm. For this purpose, two commercial powders containing graphene nanoplatelets with lateral dimensions of either ≈100 nm or in the micrometer range are compared. These larger ones exist as stack of graphene layers which is inspected with scanning electron microscopy. Both kinds of particles are then functionalized with either oxygen or fluorine. The size of the graphene particles is found to influence the degree of functionalization. Only the combination of XPS and HAXPES allows to detect the functionalization at the outermost surface of the particles or even of the stacks and to provide new insights into the functionalization process.
Over the last decades, bone tissue engineering has increasingly become a research focus in the field of biomedical engineering, in which biomaterials play an important role because they can provide both biomechanical support and osteogenic microenvironment in the process of bone regeneration. Among these biomaterials, two-dimensional (2D) nanomaterials have recently attracted considerable interest owing to their fantastic physicochemical and biological properties including great biocompatibility, excellent osteogenic capability, large specific surface area, and outstanding drug loading capacity. In this review, we summarize the state-of-the-art advances in 2D nanomaterials for bone tissue engineering. Firstly, we introduce the most explored biomaterials used in bone tissue engineering and their advantages. We then highlight the advances of cutting-edge 2D nanomaterials such as graphene and its derivatives, layered double hydroxides, black phosphorus, transition metal dichalcogenides, montmorillonite, hexagonal boron nitride, graphite phase carbon nitride, and transition metal carbonitrides (MXenes) used in bone tissue engineering. Finally, the current challenges and future prospects of 2D nanomaterials for bone tissue regeneration in process of clinical translation are discussed.
Graphene, the world's thinnest two-dimensional (2D) carbon material, with the highly ordered and repeated atomic structure and its excellent properties such as mechanical, electrical, optical, chemical, and thermal properties, has been extensively studied and applied in materialogy, physics, biomedicine and other fields in recent years. In the case of biomedical applications, the advent of graphene-based materials (GBMs) has resulted in excellent biomedical materials with a wide range of applications. Compared with the published reviews of graphene-based biomedical materials, we systematically and comprehensively introduced the properties of graphene-based biomaterials from the perspective of biomedical applications. In addition, we introduced the structure and preparation methods of graphene and its derivatives, and summarized recent advances on GBMs in the biomedical field, including drug carriers, biosensors, tissue engineering, antimicrobial materials, and other forms of exploration for medical heating, radiation shielding, surgical suturing, and wastewater treatment. Finally, we discuss the current problems and challenges of GBMs and the prospect for the future development in the biomedical field.
In recent years, with advancements in bone tissue regeneration and engineering technologies, carbon-based nanomaterials (CNMs) have progressively demonstrated advantages in the therapies of critical bone defects and related diseases that conventional substances fail to develop, such as excellent mechanical properties, large specific surface, tunable surface characteristics, and superior biocompatibility. More importantly, carbon-based nanomaterials with efficient cell proliferation and osteogenic differentiation could have a significant impact on bone tissue regeneration. In this paper, we have reviewed the characteristic applications of extraordinary types of carbon-based nanomaterials (fullerene, carbon dots, carbon nanotubes, as well as graphene and its derivatives) in bone tissue regeneration and engineering based on their structural properties, with a view to presenting their unique advantages, applications, and current directions of development as specifically and comprehensively as possible.
Nanozymes, as a unique class of nanomaterials with enzyme-like properties, have attracted significant interest due to their potential applications in many significant fields. Great endeavours have been made to improve the catalytic activities of nanozymes; however, it is still a challenging issue to develop nanozymes that can functionally mimic multiplex enzymes with broader application prospects. Here, we develop a simple hydrothermal method to construct "three-in-one" nanocomposites as multifunctional nanozymes for the ultrasensitive ratiometric fluorescence detection of alkaline phosphatase (ALP). The prepared flower-like Fe3O4 nanocomposites (Fef NCs) are composed of ternary components, in which hierarchical MnO2 nanosheets (NSs) are assembled on Fe3O4 nanoparticles (NPs), followed by the decoration of CeO2 NPs. Fef NCs present tetra-enzyme-like activities, i.e., oxidase-, peroxidase-, catalase-, and superoxide dismutase-like activity. More importantly, Fef NCs can effectively catalyze the oxidation of phenolic compounds (i.e., 3,5-DTBC and dopamine) to produce the corresponding o-quinones, demonstrating specific catechol oxidase-like activity. Based on the excellent catalytic oxidation and fluorescence quenching abilities of Fef NCs, we established a ratiometric fluorescence strategy using two fluorogenic substrates for label-free, ultrasensitive, and selective detection of ALP. The fluorescence bioassay exhibits a linear relationship between the fluorescence ratio and the ALP concentration ranging from 0.2 to 1.0 mU mL-1, with a detection limit down to be 0.19 mU mL-1. Furthermore, this bioassay can detect ALP in mixture and human serum samples, presenting good selectivity as well as real-world applicability. This work not only provides a novel approach for the preparation of a multiple-enzyme-like nanozyme but also offers an advanced ratiometric fluorescence sensing platform for ultrasensitive bioanalysis.
With the development of digital healthcare technology, the demand for non-invasive monitoring of human health is rapidly increasing. In recent years, the research and application of timely, economical, and easy-to-operate wearable sensing devices have attracted much attention. Among recent studies, graphene has been widely used to improve the sensing performance of wearable sensors due to its advantages in mechanical, electrical, and thermal properties. This review mainly focuses on summarizing graphene and its derivative-based wearable sensors and their latest developments in personal health monitoring. We will first introduce the novel structure and sensing mechanism of different types of graphene sensors. Then, we summarize the latest applications of the graphene wearable sensors in human health monitoring, including human activity, heart rate, pulse, electrophysiological signal, and electronic skin. Finally, the future challenges and prospects of graphene wearable devices will be discussed.
Here, a simple and green synthesis process of Fe/N-codoped reduced graphene oxide (Fe-N-C/NG) with high electrocatalytic activity for oxygen reduction reaction (ORR) is reported. The synthesis of 3D porous structure of Fe-N-C/NG composites involves thermal drying the mixture of graphene oxide (GO), iron nitrate and aspartic acid (Asp) directly, follow by pyrolysis the mixture. The Asp is introduced as an environment-friendly nitrogen and carbon source, and the iron nitrate serves as the pore-forming agent and a gas producer that prevents the agglomeration of graphene. The as-prepared Fe-N-C/NG exhibits 3D loose porous structure with larger specific surface area (245 m² g⁻¹). The Fe-NC/NG composite exhibits the onset potential of 0.91 V, a half-wave potential (E1/2 = 0.83 V), low Tafel slope and four-electron selectivity (n=3.99) in alkaline solution. Furthermore, the stability test manifests the outstanding stability of Fe-NC/NG electrocatalyst and a superior methanol tolerance than Pt/C electrodes. Particularly, when the prepared Fe-NC/NG-3 catalyst is used as an air electrode catalyst in an assembled Zn-air battery, it exhibits a high specific capacity of 848.2 mAh gZn⁻¹ and displays more stability than Pt/C. This work provides an effective strategy for preparing high ORR and Zn-air battery performance Fe/N-codoped reduced graphene oxide materials.
Nanomaterials have received increasing attentions owing to their potential hazards to the environment and human health; however, the multi-generational toxicity of graphene oxide under consecutive multi-generational exposure scenario still remains unclear. In the present study, Caenorhabditis elegans as an in vivo model organism was employed to explore the multi-generational toxicity effects of graphene oxide and the underlying mechanisms. Endpoints including development and lifespan, locomotion behaviors, defecation cycle, brood sizes, and oxidative response were evaluated in the parental generation and subsequent five filial generations. After continuous exposure for several generations, worms grew smaller and lived shorter. The locomotion behaviors were reduced across the filial generations and these reduced trends were following the impairments of locomotion-related neurons. In addition, the extended defecation cycles from the third filial generation were in consistency with the relative size reduction of the defecation related neuron. Simultaneously, the fertility function of the nematode was impaired under consecutive exposure as reduced brood sizes and oocytes numbers, increased apoptosis of germline, and aberrant expression of reproductive related genes ced-3, ced-4, ced-9, egl-1 and ced-13 were detected in exposed worms. Furthermore, the antioxidant enzyme, SOD-3 was significantly increased in the parent and filial generations. Thus, continuous multi-generational exposure to graphene oxide caused damage to the neuron development and the reproductive system in nematodes. These toxic effects could be reflected by indicators such as growth inhibition, shortened lifespan, and locomotion behavior impairment and induced oxidative response.
Thanks to their reduced size, great surface area, and capacity to interact with cells and tissues, nanomaterials present some attractive biological and chemical characteristics with potential uses in the field of biomedical applications. In this context, graphene and its chemical derivatives have been extensively used in many biomedical research areas from drug delivery to bioelectronics and tissue engineering. Graphene-based nanomaterials show excellent optical, mechanical, and biological properties. They can be used as a substrate in the field of tissue engineering due to their conductivity, allowing to study, and educate neural connections, and guide neural growth and differentiation; thus, graphene-based nanomaterials represent an emerging aspect in regenerative medicine. Moreover, there is now an urgent need to develop multifunctional and functionalized nanomaterials able to arrive at neuronal cells through the blood-brain barrier, to manage a specific drug delivery system. In this review, we will focus on the recent applications of graphene-based nanomaterials in vitro and in vivo, also combining graphene with other smart materials to achieve the best benefits in the fields of nervous tissue engineering and neural regenerative medicine. We will then highlight the potential use of these graphene-based materials to construct graphene 3D scaffolds able to stimulate neural growth and regeneration in vivo for clinical applications.
As a member of nano-carbon compound, nanodiamonds (ND) with diverse structure, small size and relative low toxicity has been extensively explored for different applications especially as delivery vehicles for drugs. However, surface functionalization of ND with polymers is still required to overcome their poor water dispersibility and improve drug delivery performance. In this work, we reported a simple photocatalytic atom transfer radical polymerization (ATRP) method for surface functionalization of ND by using FeBr3 as the photoredox catalyst. Owing to the introduction of water dispersible 2-methacryloyloxyethyl phosphorylcholine (MPC), resultant NDs-MPC displayed improved water dispersibility and low toxicity. The anticancer agent DOX could be loaded on NDs-MPC efficiently and controlled release from ND-P-DOX complexes. The cell viability and cell imaging results demonstrated that DOX can be transported into cells and maintained its corresponding therapeutic effect. More importantly, as compared with traditional ATRP, photocatalytic ATRP could not only operate under rather mild conditions but also could avoid utilization of expensive and toxic agents. Considered the advantages of photocatalytic ATRP and ND, the method developed in this work could be a promising strategy for fabrication of multifunctional ND-based composites for different applications.
Accurate and reliable quantification of tumor biomarkers in clinical samples is of vital importance for early stage diagnosis and treatment of cancer. However, a poor specificity of prostate specific antigen (PSA) testing alone fostering overdetection and overtreatment, remains a great controversy in prostate cancer (PCa) screening. Here we report an electrochemical aptasensor using hierarchical MoS2 nanostructuring and SiO2 nano-signal amplification for simultaneous detection of dual PCa biomarkers, PSA and sarcosine, to enhance the diagnostic performance of PCa. In this strategy, hierarchical flower-like MoS2 nanostructures as functional interface accelerated intermolecular accessibility and improved DNA hybridization efficiency. Moreover, the spherical SiO2 nanoprobe that conjugated with both electroactive tags and DNA probes, allowed effective electrochemical signal amplification. By deliberately designing different hybridization modes, we individually implemented the optimization of PSA and sarcosine sensing system. Based on this, simultaneous determination of PSA and sarcosine was achieved, with limit of detection (LOD) down to 2.5 fg/mL and 14.4 fg/mL, respectively, as well as excellent selectivity. More importantly, using this approach, we could directly differentiate cancer patients with healthy ones for clinical serum samples. The ultrasensitive biosensor provides single-step analysis with simple operation and a small sample volume (∼12 μL), shedding new light on accurate diagnosis and early-detection of cancer in clinical applications.
Graphene oxide (GO)-a carbon allotrope is widely used in aptamer generation process called SELEX (systematic evolution of ligands by exponential enrichment) and efficiently adsorbs non-target specific ssDNA onto its surface during the partitioning step of SELEX. The amount of GO required to adsorb ssDNA is high that imposes new challenges. Here, we have demonstrated graphene nanoplatelets (GrNP) that can be exploited with less material for efficient partitioning. Further, we have compared the non-target specific ssDNA adsorption on graphene oxide (GO), and graphene nanoplatelets (GrNP) and fabricated the “partitioning cartridge” for efficient separation of target (Monocrotophos and Endosulfan) bound-ssDNA from unbound ssDNA (non-target specific). To fabricate the partitioning cartridge, the spin column was utilized from common molecular biology lab waste. The fabricated “partition cartridge” alienated the target bound ssDNA efficiently and used further for polymerase chain reaction successfully. The fabricated partitioning cartridge is easy to fabricate, cost effective and recycles the plastic waste thus the environment friendly approach.
Graphene-based materials (GMs) have great application prospects in bone tissue engineering due to their osteoinductive ability and antimicrobial activity. GMs induce osteogenic differentiation through several mechanisms and pathways in bone tissue engineering. First of all, the surface and high hardness of the porous folds of graphene or graphene oxide (GO) can generate mechanical stimulation to initiate a cascade of reactions that promote osteogenic differentiation without any chemical inducers. In addition, change of the extracellular matrix (ECM), regulation of macrophage polarization, the oncostatin M (OSM) signaling pathway, the MAPK signaling pathway, the BMP signaling pathway, the Wnt/β-catenin signaling pathway and other pathways are involved in GMs’ regulation of osteogenesis. In bone tissue engineering, GMs prevent the formation of microbial biofilms mainly through preventing microbial adhesion and killing them. The former is mainly achieved by reducing surface free energy (SFE) and increasing hydrophobicity. The latter mainly includes oxidative stress and photothermal/photodynamic effects. Graphene and its derivatives (GDs) are mainly combined with bioactive ceramic materials, metal materials and macromolecular polymers to play an antimicrobial effect in bone tissue engineering. Concentration, number of layers and type of GDs often affect the antimicrobial activity of GMs. In this paper, we reviewed relevant osteoinductive and antimicrobial mechanisms of GMs and their applications in bone tissue engineering.
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The development of next‐generation of bioinks aims to fabricate anatomical size 3D scaffold with high printability and biocompatibility. Along with the progress in 3D bioprinting, 2D nanomaterials (2D NMs) prove to be emerging frontiers in the development of advanced materials owing to their extraordinary properties. Harnessing the properties of 2D NMs in 3D bioprinting technologies can revolutionize the development of bioinks by endowing new functionalities to the current bioinks. First the main contributions of 2D NMS in 3D bioprinting technologies are categorized here into six main classes: 1) reinforcement effect, 2) delivery of bioactive molecules, 3) improved electrical conductivity, 4) enhanced tissue formation, 5) photothermal effect, 6) and stronger antibacterial properties. Next, the recent advances in the use of each certain 2D NMs (1) graphene, 2) nanosilicate, 3) black phosphorus, 4) MXene, 5) transition metal dichalcogenides, 6) hexagonal boron nitride, and 7) metal–organic frameworks) in 3D bioprinting technology are critically summarized and evaluated thoroughly. Third, the role of physicochemical properties of 2D NMSs on their cytotoxicity is uncovered, with several representative examples of each studied 2D NMs. Finally, current challenges, opportunities, and outlook for the development of nanocomposite bioinks are discussed thoroughly.
Nanomaterials with enzyme-like activity (nanozymes) have been of great interest in broad applications ranging from biosensing to biomedical applications. Despite that much effort has been devoted to the development of the synthesis and applications of nanozymes, it is essential to understand the interactions between nanozymes and most commonly used biomolecules, i.e., avidin, streptavidin (SA), bovine serum albumin (BSA), immunoglobulin G (IgG), and glutathione (GSH), yet they have been rarely explored. Here, a series of bio-nano interfaces were constructed through direct immobilization of proteins on a variety of iron oxide and carbon-based nanozymes with different dimensions, including Fe3O4 nanoparticles (NPs, 0D), Fe3O4@C NPs (0D), Fe3O4@C nanowires (NWs, 1D), and graphene oxide nanosheets (GO NSs, 2D). Such interfaces enabled the modulation of the catalytic activities of the nanozymes with varying degrees, which allowed a good identification of multiplex proteins with high accuracy. Given the maximum inhibition on Fe3O4@C NP by BSA, we established molecular switches based on aptamer and toehold DNA, as well as Boolean logic gates (AND and NOR) in response to both DNA and proteins. Also importantly, we developed an on-particle reaction strategy for colorimetric detection of GSH with ultrahigh sensitivity and good specificity. The proposed sensor achieved a broad dynamic range spanning 7 orders of magnitude with a detection limit down to 200 pg mL-1, which was better than that of an in-solution reaction-based biosensor by 2 orders of magnitude. Furthermore, we explored the mechanisms of the interactions at bio-nano interfaces by studying the interfacial factors, including surface coverage, salt concentration, and the curvature of the nanozyme. This study offered new opportunities in the elaborate design and better utilization of nanozymes for bioanalysis in clinical diagnosis and in vivo detection.
Reducing the friction force between the commercial archwire and bracket during the orthodontic treatment in general dental practice has attracted worldwide interest. An investigation on the friction and wear behaviors of the uncoated and carbon film coated stainless steel archwires running against stainless steel brackets was systematically conducted. The carbon films were prepared at substrate bias voltages from +5 to +50 V using an electron cyclotron resonance plasma sputtering system. With increasing substrate bias voltage, local microstructures of the carbon films evolved from amorphous carbon to graphene nanocrystallites. Both static and stable friction coefficients of the archwire-bracket contacts sliding in dry and wet (artificial saliva) conditions decreased with the deposition of carbon films on the archwires. Low friction coefficient of 0.12 was achieved in artificial saliva environment for the graphene sheets embedded carbon (GSEC) film coated archwire. Deterioration of the friction behavior of the GSEC film coated archwire occurred after immersion of the archwire in artificial saliva solution for different periods before friction test. However, moderate friction coefficient of less than 0.30 sustained after 30 days immersion periods. The low friction mechanism is clarified to be the formation of salivary adsorbed layer and graphene sheets containing tribofilm on the contact interfaces. The robust low friction and low wear performances of the GSEC film coated archwires make them good candidates for clinical orthodontic treatment applications.
Graphene, a single-layer network of carbon atoms, has outstanding electrical and mechanical properties. Graphene ribbons with nanometre-scale widths (nanoribbons) should exhibit half-metallicity and quantum confinement. Magnetic edges in graphene nanoribbons have been studied extensively from a theoretical standpoint because their coherent manipulation would be a milestone for spintronic and quantum computing devices. However, experimental investigations have been hampered because nanoribbon edges cannot be produced with atomic precision and the graphene terminations that have been proposed are chemically unstable. Here we address both of these problems, by using molecular graphene nanoribbons functionalized with stable spin-bearing radical groups. We observe the predicted delocalized magnetic edge states and test theoretical models of the spin dynamics and spin–environment interactions. Comparison with a non-graphitized reference material enables us to clearly identify the characteristic behaviour of the radical-functionalized graphene nanoribbons. We quantify the parameters of spin–orbit coupling, define the interaction patterns and determine the spin decoherence channels. Even without any optimization, the spin coherence time is in the range of microseconds at room temperature, and we perform quantum inversion operations between edge and radical spins. Our approach provides a way of testing the theory of magnetism in graphene nanoribbons experimentally. The coherence times that we observe open up encouraging prospects for the use of magnetic nanoribbons in quantum spintronic devices.
Variations of the lattice parameter can significantly change the properties of a material, and, in particular, its electronic behaviour. In the case of graphene, however, variations of the lattice constant with respect to graphite have been limited to less than 2.5% due to its well-established high in-plane stiffness. Here, through systematic electronic and lattice structure studies, we report regions where the lattice constant of graphene monolayers grown on copper by chemical vapour deposition increases up to ~7.5% of its relaxed value. Density functional theory calculations confirm that this expanded phase is energetically metastable and driven by the enhanced interaction between the substrate and the graphene adlayer. We also prove that this phase possesses distinctive chemical and electronic properties. The inherent phase complexity of graphene grown on copper foils revealed in this study may inspire the investigation of possible metastable phases in other seemingly simple heterostructure systems.
The interest in graphene and its translation into commercial products have been expanding at high pace. In regard to previously described pulmonary safety concerns for carbon nanomaterials, there is a great need to define parameters guiding interactions between graphene-based materials and pulmonary system. The aim of present study was to determine the importance of two critical parameters: lateral dimensions of the material and coating with proteins in relation to each other and their pulmonary impact. Endotoxin-free materials with distinct lateral dimensions – s-GO (50 – 200 nm) and l-GO (5 – 15 µm) were produced and thoroughly characterized. Exploiting intrinsic fluorescence of GO and using confocal live-cell imaging, we visualized the behavior of the cells in response to the material in real time. Although BEAS-2B cells internalized GO efficiently, l-GO was linked to higher plasma membrane interactions correlated with elevated ROS levels, pro-inflammatory response and greater cytotoxicity, in agreement with the oxidative stress paradigm. For both GO types, the presence of serum alleviated lipid peroxidation of plasma membrane and decreased intracellular ROS levels. However, protein coating was not enough to entirely mitigate toxicity and inflammatory response induced by l-GO. In vitro results were validated in vivo, as l-GO was more prone to induce pulmonary granulomatous response in mice compared to s-GO. In conclusion, lateral dimension of GO played more important role than serum protein coating in determining biological responses to the material. It was also demonstrated that time-lapse imaging of live cells interacting with label-free GO sheets can be used as a tool to assess GO induced cytotoxicity.
Bacterial infections may lead to diverse acute or chronic diseases (e.g., inflammation, sepsis and cancer). New antibiotics against bacteria are rarely discovered in recent years, which necessitates the exploration of new antibacterial agents. Engineered nanomaterials (ENMs) have been extensively studied for antibacterial use because of their long lasting killing effects in wide spectra of bacteria. Graphene oxide (GO) is one of the most widely studied ENMs and exhibit strong bactericidal effects. The physicochemical properties of GO play important roles in bacterial killing by triggering a cascade of toxic events. Many studies have explored the signaling pathways of GO in bacteria. Although molecular initiating events (MIEs) of GO in bacteria dominate its killing efficiency as well as toxicity mechanisms, they have been rarely reviewed. In this report, we discussed the structure–activity relationships (SARs) involved in GO-induced bacterial killing and the MIEs including redox reaction with biomolecules, mechanical destruction of membranes and catalysis of extracellular metabolites. Furthermore, we summarized the clinical or commercial applications of GO-based antibacterial products and discussed their biosafety in mammal. Finally, we reviewed the remaining challenges in GO for antibacterial applications, which may offer new insights for the development of nano antibacterial studies.
A method for enhancing the micro-hardness and tensile properties of cross-linked ultrahigh molecular weight polyethylene (UHMWPE) for total joint implants by radiation cross-linking after adding vitamin-E (VE) and graphene oxide (GO) was reported in this paper. Vitamin E was blended with UHMWPE powder at a concentration of 0.1 wt%, followed by adding GO at a concentration of 0.5 wt% and subsequently irradiated with ⁶⁰Co gamma-rays at 100 kGy. The GO/VE/UHMWPE composite showed improved micro-hardness (∼8%), Young's modulus (∼28%), yield stress (∼33%) and fracture stress (∼37%) in comparison with UHMWPE. The OI of irradiated UHMWPE decreased from 1.9 to 0.7 after blending with VE and the OI of irradiated VE/UHMWPE increased from 0.7 to 1.3 after filling with GO. In addition, the addition of GO further reduced the gel content.
We have developed a cost-effective and portable graphene-enabled biosensor to detect Zika virus with a highly specific immobilized monoclonal antibody. Field Effect Biosensing (FEB) with monoclonal antibodies covalently linked to graphene enables real-time, quantitative detection of native Zika viral (ZIKV) antigens. The percent change in capacitance in response to doses of antigen (ZIKV NS1) coincides with levels of clinical significance with detection of antigen in buffer at concentrations as low as 450pM. Potential diagnostic applications were demonstrated by measuring Zika antigen in a simulated human serum. Selectivity was validated using Japanese Encephalitis NS1, a homologous and potentially cross-reactive viral antigen. Further, the graphene platform can simultaneously provide the advanced quantitative data of nonclinical biophysical kinetics tools, making it adaptable to both clinical research and possible diagnostic applications. The speed, sensitivity, and selectivity of this first-of-its-kind graphene-enabled Zika biosensor make it an ideal candidate for development as a medical diagnostic test.
Reduced graphene oxide (rGO) is a promising antibacterial material, the efficacy of which can be further enhanced by the addition of silver nanoparticles (nAg). In this study, the mechanisms of antibacterial activity of rGO–nAg nanocomposite against several important human pathogenic multi-drug resistant bacteria, namely Gram-positive coccal Staphylococcus aureus and Gram-negative rod-shaped Escherichia coli and Proteus mirabilis are investigated. At the same concentration (100 µg/ml), rGO–nAg nanocomposite was significantly more effective against all three pathogens than either rGO or nAg. The nanocomposite was equally active against P. mirabilis and S. aureus as systemic antibiotic nitrofurantoin, and significantly more effective against E. coli. Importantly, the inhibition was much faster in the case of rGO–nAg nanocomposite compared to nitrofurantoin, attributed to the synergistic effects of rGO–nAg mediated contact killing and oxidative stress. This study may provide new insights for the better understanding of antibacterial actions of rGO–nAg nanocomposite and for the better designing of graphene-based antibiotics or other biomedical applications.
Reliable determination of binding kinetics and affinity of DNA hybridization and single-base mismatches plays an essential role in systems biology, personalized and precision medicine. The standard tools are optical-based sensors that are difficult to operate in low cost and to miniaturize for high-throughput measurement. Biosensors based on nanowire field-effect transistors have been developed, but reliable and cost-effective fabrication remains a challenge. Here, we demonstrate that a graphene single-crystal domain patterned into multiple channels can measure time- and concentration-dependent DNA hybridization kinetics and affinity reliably and sensitively, with a detection limit of 10 pM for DNA. It can distinguish single-base mutations quantitatively in real time. An analytical model is developed to estimate probe density, efficiency of hybridization and the maximum sensor response. The results suggest a promising future for cost-effective, high-throughput screening of drug candidates, genetic variations and disease biomarkers by using an integrated, miniaturized, all-electrical multiplexed, graphene-based DNA array.
The study of graphene-based antivirals is still at a nascent stage and the photothermal antiviral properties of graphene have yet to be studied. Here, we design and synthesize sulfonated magnetic nanoparticles functionalized with reduced graphene oxide (SMRGO) to capture and photothermally destroy herpes simplex virus type 1 (HSV-1). Graphene sheets were uniformly anchored with spherical magnetic nanoparticles (MNPs) of varying size between ~5-25 nm. Fourier-transform infrared spectroscopy (FT-IR) confirmed the sulfonation and anchoring of MNPs on the graphene sheets. Upon irradiation of the composite with near-infrared light (NIR, 808 nm, 7 min), SMRGO (100 ppm) demonstrated superior (~99.99%) photothermal antiviral activity. This was probably due to the capturing efficiency, unique sheet-like structure, high surface area and excellent photothermal properties of graphene. In addition, electrostatic interactions of MNPs with viral particles appear to play a vital role in the inhibition of viral infection. These results suggest that graphene composites may help to combat viral infections including, but not only, HSV-1.
Goraphene derivatives (GD) are currently being evaluated for technological and biomedical applications owing to their unique physico-chemical properties over other carbon allotrope such as carbon nanotubes (CNTs). But, the possible association of their properties with underlying in vitro effects have not fully examined. Here, we assessed the comparative interaction of three GD - graphene oxide (GO), thermally reduced GO (TRGO) and chemically reduced GO (CRGO), which significantly differ in their lateral size and functional groups density, with phenotypically different human lung cells; bronchial epithelial cells (BEAS-2B) and alveolar epithelial cells (A549). The cellular studies demonstrate that GD significantly ineternalize and induce oxidative stress mediated cytotoxicity in both cells. The toxicity intensity was in line with the reduced lateral size and increased functional groups revealed more toxicity potential of TRGO and GO respectively. Further, A549 cells showed more susceptibility than BEAS-2B which reflected cell type dependent differential cellular response. Molecular studies revealed that GD induced differential cell death mechanism which was efficiently prevented by their respective inhibitors. This is prior study to the best of our knowledge involving TRGO for its safety evaluation which provided invaluable information and new opportunities for GD based biomedical applications.
Autophagy is a basic cellular process that decomposes damaged organelles and aberrant proteins. Dysregulation of autophagy is implicated in pathogenesis of neurodegenerative disorders, including Parkinson’s disease (PD). Pharmacological compounds that stimulate autophagy can provide neuroprotection in models of PD. Nanoparticles have emerged as regulators of autophagy and have been tested in adjuvant therapy for diseases. In this present study, we explore the effects of quantum dots (QDs) that can induce autophagy in a cellular model of Parkinson’s disease. CdTe/CdS/ZnS QDs protect differentiated rat pheochromocytoma PC12 cells from MPP+-induced cell damage, including reduced viability, apoptosis and accumulation of α-Synuclein, a characteristic protein of PD. The protective function of QDs is autophagy-dependent. In addition, we investigate the interaction between quantum dots and autophagic pathways and identify beclin1 as an essential factor for QDs-induced autophagy. Our results reveal new promise of QDs in the theranostic of neurodegenerative diseases.
The significant role of telomeres in cells has attracted much attention since they were discovered. Fluorescence imaging is an effective method to study subcellular structures like telomeres. However, the diffraction limit of traditional optical microscope hampers further investigation on them. Recent progress on superresolution fluorescence microscopy has broken this limit. In this work, we used stimulated emission depletion (STED) microscope to observe fluorescence-labeled telomeres in interphase cell nuclei. The results showed that the size of fluorescent puncta representing telomeres under the STED microscope was much smaller than that under the confocal microscope. Two adjacent telomeres were clearly separated via STED imaging, which could hardly be discriminated by confocal microscopy due to the diffraction limit. We conclude that STED microscope is a more powerful tool that enable us to obtain detailed information about telomeres.
Ag2S quantum dot with excellent NIR-Ⅱ fluorescence can provide deeper tissue penetration (>1.1 cm) and higher spatiotemporal resolution (25 μm, 50 ms) in comparison to the conventional fluorophore. In this study, we designed a NIR-Ⅱ probe based Ag2S quantum dot for imaging of brain tumor. Angiopep-2 was used to modify Ag2S quantum dot, which is a 19-mer peptide exhibiting high binding efficiency with low-density lipoprotein receptor-related protein-1 (LRP-1) of blood brain barrier and glioma. Due to the surface of Ag2S quantum dots with carboxyl groups and angiopep-2 peptide with amino groups, Ag2S was conjugated with Angiopep-2 (Ag2S-ANG) through the condensation reaction of amino and carboxyl groups mediated by EDC and NHS. The structure, size and spectral properties of Ag2S-ANG were characterized by agarose electrophoresis, dynamic light scattering transmission, electron microscope (TEM), UV-vis spectrometer and NIR fluorescence spectrometer, respectively. Results showed that Ag2S-ANG had a short migration distance compared with Ag2S in the agarose gel electrophoresis. The hydrate particle size of Ag2S was approximately 6 nm, Ag2S-ANG was approximately 8 nm and its zeta potential exhibited electropositive reinforcement, zeta potential of Ag2S is -11.47±1.56 mV and Ag2S-ANG is +28.7±1.35 mV. Ag2S-ANG exhibited similar absorbance and fluorescence spectra to Ag2S, except a slight enhancement of emission peak. These results indicated that Ag2S-ANG was synthesized successfully. We further observed its cell cytotoxicity, distribution and uptake in Uppsala 87 Malignant Glioma cells(U87MG), and in vivo distribution in the solid tumor-bearing mouse. Ag2S-ANG had no obvious cytotoxicity when the concentration is inferior to 100 μg/mL and had more uptake in U87MG cells than that of Ag2S. In animal experiments, glioma tumor-bearing mice were used to investigate the distribution and tumor targeting of Ag2S-ANG. Results showed that Ag2S-ANG can distribute and accumulate in subcutaneous tumor site, indicating that Ag2S-ANG had the potential of targeting the glioma cells. © 2018 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.
Graphene and its derivatives have recently attracted much attention for sensing and deactivating pathogens. However, the mechanism of multivalent interactions at the graphene–pathogen interface is not fully understood. Since different physicochemical parameters of graphene play a role at this interface, control over graphene's structure is necessary to study the mechanism of these interactions. In this work, different graphene derivatives and also zwitterionic graphene nanomaterials (ZGNMs) were synthesized with defined exposure, in terms of polymer coverage and functionality, and isoelectric points. Then, the switchable interactions of these nanomaterials with E. coli and Bacillus cereus were investigated to study the validity of the generally proposed “trapping” and “nano-knives” mechanisms for inactivating bacteria by graphene derivatives. It was found that the antibacterial activity of graphene derivatives strongly depends on the accessible area, i.e. edges and basal plane of sheets and tightness of their agglomerations. Our data clearly confirm the authenticity of “trapping” and “nano-knives” mechanisms for the antibacterial activity of graphene sheets.
Patterning graphene allows to precisely tune its properties to manufacture flexible functional materials or miniaturized devices for electronic and biomedical applications. However, conventional lithographic techniques are cumbersome for scalable producing time- and cost-effective graphene patterns, thus greatly impeding their practical applications. Here we present a simple scalable fabrication of wafer-scale 3D graphene micropatterns by direct laser tuning expansion and reduction of graphene oxide using a standard LightScribe DVD burner. This one-step laser-scribed process can produce custom-made 3D graphene patterns with dimensions ranging from microscale up to decimeter-scale on a single disc in 20 min or less. Via control over laser-scribing parameters, the resulting various 3D graphene patterns are exploited as scaffolds for controlling cell alignment. The 3D graphene patterns demonstrate their potential to biomedical applications, beyond fields of electronics and photonics, which will allow to incorporate the flexible graphene patterns for 3D cells or tissues culture to promote tissue engineering and drug testing applications.
The aggregation of Amyloid-β (Aβ), which involves the formation of small oligomers and mature fibrils, has been received considerable attention in the past decades, due to its close link with Alzheimer’s disease (AD). The inhibition of β-sheet formation has been considered as the primary therapeutic strategy for AD. In this respect, graphene oxide (GO) gained significant attention because of its high solubility, good biocompatibility and inhibitory effect on the aggregation of Aβ and the 33-42 fragment (Aβ33-42). However, the inhibitory mechanism at atomic level remains elusive. Herein, we investigated the oligomerization of Aβ33-42 by performing replica exchange molecular dynamics simulations on four Aβ33-42 peptide chains in the absence and presence of two different sizes of GO. Our simulations show that isolated Aβ33-42 can form fibril-prone extended β-sheets and barrel-like structures, whereas they are suppressed in the presence of GO nanosheets. Our data reveal that GO inhibits Aβ33-42 oligomerization by making Aβ33-42 peptides separated from each other through strong interactions with M35. With the same total number of atoms, GO120 displays better inhibitory effect than GO60 by providing a larger effective contact surface area. This study provides molecular mechanism of GO in inhibiting the aggregation of Aβ33-42, which might offer a theoretical insight into the design of drug against AD at the atomic level.
There currently exists increasing concerns on the development of a kind of high-performance SERS platform, which is suitable for sensing applications ranging from molecular to cellular (e.g., bacteria) level. Herein, we develop a novel kind of universal SERS chip, made of graphene (G)-silver nanoparticles (AgNPs)-silicon (Si) sandwich nanohybrids (G@AgNPs@Si), in which AgNPs are in situ grown on silicon wafer through hydrofluoric acid-etching assisted chemical reduction, followed by coating with a single-layer graphene via polymer-protective etching method. The resultant chip features strong, stable, reproducible surface-enhanced Raman scattering (SERS) effect, and reliable quantitative capability. By virtues of these merits, the G@AgNPs@Si platform is capable for not only molecular detection, quantification but also cellular analysis in real systems. As a proof-of-concept application, the chip allows ultrahigh sensitive and reliable detection of adenosine triphosphate (ATP), with detection limit of ~1 pM. In addition, the chip, served as novel multifunctional platform, enables simultaneous capture, discrimination, and inactivation of bacteria. Typically, the bacterial capture efficiency is 54% at 108CFU mL-1bacteria, and the antibacterial rate reaches 93% after 24-h treatment. Of particular note, Escherichia coli and Staphylococcus aureus spiked into blood can be readily distinguished via the chip, suggesting its high potential for clinical applications.
Many theoretical studies predict that DNA sequencing should be feasible by monitoring the transverse current through a graphene nanoribbon while a DNA molecule translocates through a nanopore in that ribbon. Such a readout would benefit from the special transport properties of graphene, provide ultimate spatial resolution because of the single-atom layer thickness of graphene, and facilitate high-bandwidth measurements. Previous experimental attempts to measure such transverse inplane signals were however dominated by a trivial capacitive response. Here, we explore the feasibility of the approach using a custom-made differential current amplifier that discriminates between the capacitive current signal and the resistive response in the graphene. We fabricate well-defined short and narrow (30nmx30nm) nanoribbons with a 5nm nanopore in graphene with a high-temperature scanning transmission electron microscope to retain the crystallinity and sensitivity of the graphene. We show that, indeed, resistive modulations can be observed in the graphene current due to DNA translocation through the nanopore, thus demonstrating that DNA sensing with inplane currents in graphene nanostructures is possible. The approach is however exceedingly challenging due to low yields in device fabrication connected to the complex multistep device layout.
Group-V elemental monolayers were recently predicted to exhibit exotic physical properties like nontrivial topological properties, or quantum anomalous Hall effect, which would make them very suitable for applications in next-generation electronic devices. The free-standing group-V monolayer materials usually have a buckled honeycomb form, in contrast with the flat graphene monolayer. Here, we report epitaxial growth of atomically thin flat honeycomb monolayer of group-V element antimony on a Ag(111) substrate. Combined study of experiments and theoretical calculations verify the formation of a uniform and single-crystalline antimonene monolayer without atomic wrinkles, as a new honeycomb analogue of graphene monolayer. Directional bonding between adjacent Sb atoms and weak antimonene-substrate interaction are confirmed. The realization and investigation of flat antimonene honeycombs extends the scope of two-dimensional atomic-thick structures and provides a promising way to tune topological properties for future technological applications.
While 2-dimensional graphene oxide (GO) is used increasingly in biomedical applications, there is uncertainty on how specific physicochemical properties relate to biocompatibility in mammalian systems. Although properties such as lateral size and the colloidal properties of the nanosheets are important, the specific material properties that we address here is the oxidation state and reactive surface groups on the planar surface. In this study, we used a GO library, comprised of pristine, reduced (rGO), and hydrated GO (hGO), in which quantitative assessment of the hydroxyl, carboxyl, epoxy and carbon radical contents were used to study the impact on epithelial cells and macrophages, as well as in the murine lung. Strikingly, we observed that hGO, which exhibits the highest carbon radical density, was responsible for the generation of cell death in THP-1 and BEAS-2B cells as a consequence of lipid peroxidation of the surface membrane, membrane lysis, and cell death. In contrast, pristine GO had lesser effects while rGO showed extensive cellular uptake with minimal effects on viability. In order to see how these in vitro effects relate to adverse outcomes in the lung, mice were exposed to GOs by oropharyngeal aspiration. Animal sacrifice after 40h demonstrated that hGO was more prone than other materials in generating acute lung inflammation, accompanied by the highest lipid peroxidation in alveolar macrophages, cytokine production (LIX, MCP-1) and LDH release in bronchoalveolar lavage fluid. Pristine GO showed less toxicity while rGO had minimal effects. In summary, we demonstrate that the surface oxidation state and carbon radical content play major roles in the induction of toxicity by GO in mammalian cells and the lung.
The localized surface plasmon resonance of metal nanoparticles is the collective oscillation of electrons on particle surface. The localized electromagnetic interaction brings a series of novel functions and applications. Plasmonic nanomaterials have been the significant part of nanophotonics, since its' localized surface plasmon resonance (LSPR) can focus incident phonons on the nanoscale surface. The unique plasmonic property is highly sensitive to their size, shape, coupling between particles as well as local dielectric environment. These properties can be utilized for the development of new biosensing and bioimaging applications. To date, many LSPR sensing strategies have been developed with outstanding measurement capabilities, enabling detection down to the single-molecule level, including LSPR-based sensing, surface-enhanced Raman scattering, metal-enhanced fluorescence, dark-field light-scattering, metal-mediated fluorescence resonance energy transfer. Moreover, the unique optical stability of plasmonic nanoparticles enables them as ideal probes in cellular imaging. Here, recent examples on application of plasmonic nanostructures in sensing and bioimaging are summarized, and perspectives are provided as well. © 2017 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.
To investigate the mechanism of inhibition of silver ions on microorganisms, two strains of bacteria, namely Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), were treated with AgNO3 and studied using combined electron microscopy and X-ray microanalysis. Similar morphological changes occurred in both E. coli and S. aureus cells after Ag⁺ treatment. The cytoplasm membrane detached from the cell wall. A remarkable electron-light region appeared in the center of the cells, which contained condensed deoxyribonucleic acid (DNA) molecules. There are many small electron-dense granules either surrounding the cell wall or depositing inside the cells. The existence of elements of silver and sulfur in the electron-dense granules and cytoplasm detected by X-ray microanalysis suggested the antibacterial mechanism of silver: DNA lost its replication ability and the protein became inactivated after Ag⁺ treatment. The slighter morphological changes of S. aureus compared with E. coli recommended a defense system of S. aureus against the inhibitory effects of Ag⁺ ions. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 662–668, 2000.
Based on the unique physicochemical properties of graphene quantum dots (GQDs), we developed a novel type of theranostic agent by loading anti-cancer drug doxorubicin (DOX) to GQD’s surface and conjugating Cy5.5 (Cy) dye to GQD though a cathepsin D-responsive (P) peptide. Such type of agents demonstrated superior therapeutic performance both in vitro and in vivo due to the improved tissue penetration and cellular uptake. More importantly, they are capable of functioning as probes for programmed tracking the delivery and release of anti-cancer drug as well as drug-induced cancer cell apoptosis through GQD’s, DOX’s and Cy’s charateristic fluorescence, respectively.
Graphene nanomaterials have many diverse applications, but are considered to be emerging environmental pollutants. Thus, their potential environmental risks and biosafety are receiving increased attention. Bioaccumulation and toxicity evaluations in plants are essential for biosafety assessment. In this study, ¹³C-stable isotope labeling of the carbon skeleton of graphene oxide (GO) was applied to investigate the bioaccumulation and toxicity of GO in wheat. Bioaccumulation of GO was accurately quantified according to the ¹³C/¹²C ratio. Wheat seedlings were exposed to ¹³C-labeled GO at 1.0 mg/mL in nutrient solution for 15 d. ¹³C-GO accumulated predominantly in the root with a content of 112 μg/g at day 15, hindered the development and growth of wheat plants, disrupted root structure and cellular ultrastructure, and promoted oxidative stress. The GO that accumulated in the root showed extremely limited translocation to the stem and leaves. During the experimental period, GO was excreted slowly from the root. GO inhibited the germination of wheat seeds at high concentrations (≥0.4 mg/mL). The mechanism of GO toxicity to wheat may be associated with oxidative stress induced by GO bioaccumulation, reflected by the changes of malondialdehyde concentration, catalase activity and peroxidase activity. The results demonstrate that ¹³C labeling is a promising method to investigate environmental impacts and fates of carbon nanomaterials in biological systems.
Rolling circle amplification (RCA) is a simple and efficient isothermal enzymatic reaction, which has developed as a novel technologyin the field of nucleic acid amplification. Its product has a wide range of applications in the assembly and preparation of multi-functional materials. Here, we report the effects of reaction time and the concentrations of deoxyribonucleoside triphosphates (dNTPs), polymerase, and primer on the product of RCA. The RCA product was characterized by methods including agarose gel electrophoresis, ultraviolet spectroscopy, and transmission electron microscopy (TEM). The results showed that the length of the RCAproduct was significantly affected by the reaction time, especially when the reaction time was less than 30 min. With an increase of dNTPs concentrations, the concentration and chain length of the RCA product increased. However, while the concentrations oenzyme and primer had little effect on the length of the RCA product, they had a large effect on its concentration. It is worth noting that the content of the RCA product decreased significantly in the presence of excess enzyme concentration.
DNA possesses extraordinary molecular recognition properties and remarkable structural features in the nano-level material regulation fields, which have shown enormous applications in many areas. In this review, we focus on DNA nanotechnology, including aspects ranging from modular DNA self-assembly to DNA origami, in addition to the recently reported novel assembly methods. Moreover, we summarize some applications of DNA nanotechnology, such as DNA-directed nanoparticle spatial positioning and orientation, and well-defined assembly of proteins on the DNA structure, as well as its uses, such as in the biomedical field, etc. The development and potential applications of DNA nanotechnology are also discussed.
Coupling TiO2 with WO3 to develop photocatalytic heterojunctions is one of the most widely used strategies to realize their superior photoactivity. However, the interfacial charge transfer in these heterojunctions is not efficient to achieve an optimized activity. For the first time, the present study reports a facile hydrolysis-hydrothermal approach, whereby ultradispersed TiO2 nanocrystals and WO3 nanorods are concurrently anchored onto reduced graphene oxide (rGO) and formed a novel Z-scheme heterojunction photocatalyst TiO2/rGO/WO3 (TRW). Transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence spectra (PL) are employed to characterize TRW. Control experiments indicate that, in the synthesis process, glucose and the by-product sodium chloride from the hydrolysis reactions are critical for forming highly dispersed and uniform-sized TiO2 nanocrystals and WO3 nanorods. Compared with TiO2/WO3 nanocomposites, TRW shows enhanced activity for bacterial inactivation under simulated solar light. As confirmed by electrochemical characterizations and the reactive oxygen species, rGO in TRW suppresses the recombination of electron-hole pairs and boosts the O2 reduction reactions during photocatalytic process. Z-scheme electron transfer in TRW is proposed based on surface redox reactions and XPS analysis after light irradiation. This study could provide a new clue for designing graphene-based heterojunction photocatalysts for environmental applications.
We recognize the stochastic collisions of dopamine contained phospholipid vesicle on carbon fiber nanoelectrode, extending the observation of discrete collision events on nanoelectrode to biologically relevant analytes. To decrease noise interference to the technique, the dimensions of nanoelectrode was systematically investigated and optimized. Scanning electron microscopy (SEM) further supported the comparable sizes of nanoelectrode and vesicles (~100 nm in diameter). Vesicles collision and rupture on the surface of nanoelectrode led to the dopamine release from vesicles, which could be electrochemically oxidized to dopamine-o-quinone and detected via voltammetry. The comparable size of the nanoelectrode with vesicles and fast voltammetry allowed differentiation of single collision events from the current magnitudes and peak widths in the electrochemical collision experiments, which shows the efficacy of the method to characterize vesicle samples. This work provides a foundation upon which quantitative sensor technology might be built for the detection of dopamine contained vesicles with high spatial and temporal resolution.
Stimulated emission depletion (STED) microscope is one of the most prominent super-resolution bio-imaging instruments, which holds great promise for ultrahigh-resolution imaging of cells. To construct a STED microscope, it is challenging to realize temporal synchronization between the excitation pulses and the depletion pulses. In this study, we present a simple and low-cost method to achieve pulse synchronization by using a condensed fluorescent dye as a depletion indicator. By using this method, almost all the confocal microscopes can be upgraded to a STED system without losing its original functions. After the pulse synchronization, our STED system achieved sub-100-nm resolution for fluorescent nanospheres and single-cell imaging. © 2017 Science China Press and Springer-Verlag Berlin Heidelberg
The biosensing technology plays an important role in environmental monitoring, safety control and medical diagnosis. Precise control of the interaction between bio-recognition probe and the interface is critical to improve the sensitivity, specificity and selectivity of biosensors. In a typical bioprobe immobilization, the heterogeneity of self-assembled monolayers on the surface increases the binding energy barrier and decreases the recognition efficiency and rate. We found that DNA nanostructures, such as tetrahedral DNA nanostructures (TDNs), could increase the homogeneity of self-assembled monolayers via enthalpy-entropy compensation, which enables precise regulation of interfacial property at the nanoscale. By regulating the intermolecular distance of bioprobes, the hybridization efficiency and hybridization rate of DNA probes can be improved significantly. The detection limit of DNA and microRNA can be pushed down to 10 aM limit. The detection limit of antigen detection can be improved to 100 pM and the detection limit of small molecule (cocaine) can be pushed to 33 nM. By using TDNs, we developed a universal detection platform for nucleic acids, proteins, small molecules and cells with superior detection sensitivity. To further use TDN probes in cells and in vivo, we explored the transport pathways of TDNs into the cell and directed their targeting location to specific organelles. We aim to develop DNA nanostructure-based bioprobes for intracellular and in-vivo imaging. © 2017, Editorial Office of Progress in Chemistry. All right reserved.
Isothermal amplification is an efficient way to amplify DNA with high accuracy, however, the real-time monitoring for quantification analysis mostly relied on expensive and precisely designed probes. In the present study, Graphene oxide (GO)-based nano probe was used to real-time monitor the isothermal amplification process. The interaction between GO and different DNA structures was systematically investigated, including single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), DNA 3-helix, and long rolling circle amplification (RCA) and hybridization chain reaction (HCR) products, which existed in one-, two- and three-dimensional structures. It was found that the high rigid structures exhibited much lower affinity with GO than soft ssDNA, and generally the rigidity was dependent on the length of targets and the hybridization position with probe DNA. Based on these results, we successfully monitored HCR amplification process, RCA process and the enzyme restriction of RCA products with GO nanoprobe, other application including the detection of the assembly/disassembly of DNA 3-helix structures were also performed. Compared to the widely used end-point detection methods, the GO-based sensing platform is simple, sensitive, cost-effective, and especially in a real-time monitoring mode. We believe such studies can provide comprehensive understandings and evocation on design of GO-based biosensors for broad application in various fields.
Water environment pollution caused by the widespread application of beta-cypermethrin (BCP) and chlorpyrifos (CPF) in agriculture has attracted extensive concern of the world. In this study, zebrafish was used as a model to investigate the individual and joint toxicity of BCP and CPF. In the acute toxicity test, 3 hpf embryos were exposed to various concentrations of CPF, BCP and their binary mixtures (MIX) for 96 h. The results indicated that these two pesticides and mixtures induced malformation and death in larvae, and affected hatchability. These two pesticides in mixtures were verified to act together in a synergistic manner under experimental conditions. Oxidative stress assaying manifested that CPF, BCP and MIX altered CAT, SOD and GST activities and MDA content, resulting in oxidative damage in larvae. By pathology analysis, CPF (236 μg/L), BCP (5.9 μg/L) and MIX (236 μg/L CPF + 5.9 μg/L BCP) were found to trigger liver lesions and promote apoptosis in tissues. The transcriptome sequencing suggested that ECM- receptor interaction, focal adhesion, cell cycle, DNA replication, phototransduction and adherens junction pathways were closely associated with the toxicity of these two pesticides.
Graphene, a 2D carbon material has found vast application in biomedical field because of its exciting physico-chemical properties. The large planar sheet like structure helps graphene to act as an effective carrier of drug or biomolecules in enormous amount. However, limited data available on the biocompatibility of graphene upon interaction with the biological system prompts us to evaluate their toxicity in animal model. In this study organ distribution, clearance and toxicity of PEGylated reduced nanographene (PrGO) on Swiss Albino mice was investigated after intraperitoneal and intravenous administration. Biodistribution and blood clearance was monitored using confocal Raman mapping and indicated that PrGO was distributed on major organs such as brain, liver, kidney, spleen and bone marrow. Presence of PrGO in brain tissue suggests that it has the potential to cross blood brain barrier. Small amount of injected PrGO was found to excrete via urine. Repeated administration of PrGO induced acute liver injury, congestion in kidney and increased splenocytes proliferation in days following exposure. Hence the result of the study recommended that PrGO should undergo intensive safety assessment before clinical application or validated to be safe for medical use.
In recent years graphene has drawn considerable research interests for biomedical applications. However, applications of graphene in biological systems also raise concern about its possible toxicity. Here, by using live cell imaging techniques we investigate the effect of pristine graphene on the viability as well as stress of both nonneuronal and neuronal cells under physiological conditions. We find that graphene promotes cell adhesion and proliferation. Furthermore, we find that graphene has no detectable adverse effect on mitochondrial membrane potential and morphology, or autophagy levels in the cell, indicating that graphene does not induce cell stress. Our results highlight the potential of graphene to be used in biomedical applications by providing long-term and stable nonneural and neural interfaces.
Polysulfated nanomaterials that mimic the extracellular cell matrix are of great interest for their potential to modulate cellular responses and to bind and neutralize pathogens. However, control over the density of active functional groups on such biomimetics is essential for efficient interactions, and this remains a challenge. In this regard, producing polysulfated graphene derivatives with control over their functionality is an intriguing accomplishment in order to obtain highly effective 2D platforms for pathogen interactions. Here, a facile and efficient method for the controlled attachment of a heparin sulfate mimic on the surface of graphene is reported. Dichlorotriazine groups are conjugated to the surface of graphene by a one-pot [2+1] nitrene cycloaddition reaction at ambient conditions, providing derivatives with defined functionality. Consecutive step by step conjugation of hyperbranched polyglycerol to the dichlorotriazine groups and eventual conversion to the polyglycerol sulfate result in the graphene based heparin biomimetics. Scanning force microscopy, cryo-transmission electron microscopy, and in vitro bioassays reveal strong interactions between the functionalized graphene (thoroughly covered by a sulfated polymer) and vesicular stomatitis virus. Infection experiments with highly sulfated versions of graphene drastically promote the infection process, leading to higher viral titers compared to nonsulfated analogues.
We summarized the findings of toxicity studies on graphene-based nanomaterials (GNMs) in laboratory mammals. The inhalation of graphene (GP) and graphene oxide (GO) induced only minimal pulmonary toxicity. Bolus airway exposure to GP and GO caused acute and subchronic pulmonary inflammation. Large-sized GO (L-GO) was more toxic than small-sized GO (S-GO). Intratracheally administered GP passed through the air-blood barrier into the blood and intravenous GO distributed mainly in the lungs, liver, and spleen. S-GO and L-GO mainly accumulated in the liver and lungs, respectively. Limited information showed the potential behavioral, reproductive, and developmental toxicity and genotoxicity of GNMs. There are indications that oxidative stress and inflammation may be involved in the toxicity of GNMs. The surface reactivity, size, and dispersion status of GNMs play an important role in the induction of toxicity and biodistribution of GNMs. Although this review paper provides initial information on the potential toxicity of GNMs, data are still very limited, especially when taking into account the many different types of GNMs and their potential modifications. To fill the data gap, further studies should be performed using laboratory mammals exposed using the route and dose anticipated for human exposure scenarios.
Applications of graphene have extended into areas of nanobio-technology such as nanobio-medicine, nanobio-sensing, as well as nanoelectronics with biomolecules. These applications involve interactions between proteins, peptides, DNA, RNA etc. and graphene, therefore understanding such molecular interactions is essential. For example, many applications based on using graphene and peptides require peptides to interact with (e.g., noncovalently bind to) graphene at one end, while simultaneously exposing the other end to the surrounding medium (e.g., to detect analytes in solution). To control and characterize peptide behavior on a graphene surface in solution is difficult. Here we successfully probed the molecular interactions between two peptides (cecropin P1 and MSI-78(C1)) and graphene in situ and in real-time using sum frequency generation (SFG) vibrational spectroscopy and molecular dynamics (MD) simulation. We demonstrated that the distribution of various planar (including aromatic (Phe, Trp, Tyr and His)/amide (Asn and Gln)/Guanidine (Arg)) side-chains and charged hydrophilic (such as Lys) side-chains in a peptide sequence determines the orientation of the peptide adsorbed on a graphene surface. It was found that peptide interactions with graphene depend on the competition between both planar and hydrophilic residues in the peptide. Our results indicated that part of cecropin P1 stands up on graphene due to an unbalanced distribution of planar and hydrophilic residues, whereas MSI-78(C1) lies down on graphene due to an even distribution of Phe residues and hydrophilic residues. With such knowledge, we could rationally design peptides with desired residues to manipulate peptide-graphene interactions, which allows peptides to adopt optimized structure and exhibit excellent activity for nanobio-technological applications. This research again demonstrates the power to combine SFG vibrational spectroscopy and MD simulation in studying interfacial biological molecules.
With the global rise in incidence of cancer and infectious diseases, there is a need for the development of techniques to diagnose, treat and monitor these conditions. The ability to efficiently capture and isolate cells and other biomolecules from peripheral whole blood for downstream analyses is a necessary requirement. Graphene oxide (GO) is an attractive template nanomaterial for such biosensing applications. Favorable properties include its two-dimensional architecture and wide range of functionalization chemistries, offering significant potential to tailor affinity towards aromatic functional groups expressed in biomolecules of interest. However, a limitation of current techniques is that as-synthesized GO nanosheets are used directly in sensing applications and the benefits of their structural modification on the device performance have remained unexplored. Here, we report a microfluidic-free, sensitive, planar device on treated GO substrates to enable quick and efficient capture of Class-II MHC-positive cells from murine whole blood. We achieve this by using a mild thermal annealing treatment on the GO substrates, which drives a phase transformation through oxygen clustering. Using a combination of experimental observations and MD simulations, we demonstrate that this process leads to improved reactivity and density of functionalization of cell capture agents, resulting in an enhanced cell capture efficiency of 92 ± 7% at room temperature, almost double the efficiency afforded by devices made using as-synthesized GO (54 ± 3%). Our work highlights a scalable, cost-effective, general approach to improve the functionalization of GO, which creates diverse opportunities for various next-generation device applications.
Reactive oxygen species is the main contributor to photodynamic therapy. The results of this study show that a nitrogen-doped graphene quantum dot, serving as a photosensitizer, was capable of generating a higher amount of reactive oxygen species than a nitrogen-free graphene quantum dot in photodynamic therapy when photoexcited for only 3 min of 670 nm laser exposure (0.1 W cm⁻²), indicating highly improved antimicrobial effects. In addition, we found that higher nitrogen-bonding compositions of graphene quantum dots more efficiently performed photodynamic therapy actions than did the lower compositions that underwent identical treatments. Furthermore, the intrinsically emitted luminescence from nitrogen-doped graphene quantum dots and high photostability simultaneously enabled it to act as a promising contrast probe for tracking and localizing bacteria in biomedical imaging. Thus, the dual modality of nitrogen-doped graphene quantum dots presents possibilities for future clinical applications, and in particular multidrug resistant bacteria.
Efficient exfoliation of graphite in solutions to obtain high-quality graphene flakes is desirable for printable electronics, catalysis, energy storage, and composites. Graphite oxide with large lateral dimensions has an exfoliation yield of ˜100% but it has not been possible to completely remove the oxygen functional groups so that the reduced form of graphene oxide (GO) remains a highly disordered material. Here, we report a simple, rapid method to reduce GO (rGO) into pristine graphene using 1- to 2- second pulses of microwaves. The excellent structural properties are translated into mobility values of > 1000 centimeter squared per volt per second in field effect transistors (FETs) with MW-rGO as the channel material and in exceptionally high activity for MW-rGO catalyst support toward oxygen evolution reaction (OER).
Graphene is widely used as a catalyst support for improved charge separation in TiO2 photocatalysis. However, the surface oxygen reduction activity of TiO2/graphene might be hindered due to the electron storage ability of graphene. In this study, highly dispersed TiO2 and carbon dots (C-dots) co-decorated reduced graphene oxide (CTR) is synthesized via a simple hydrothermal reaction using TiCl4 and glucose. Transmission electron microscope, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis and Fourier transform IR spectroscopy are employed to characterize the CTR nanocomposite. The comparison experiment confirmed that C-dots were sourced from the carbonization of glucose. Glucose and TiCl4 which are mutual dispersants, are critical for forming highly dispersed and uniform-sized C-dots and TiO2 nanocrystals. With well dispersed TiO2 and C-dots at separated sites of reduced graphene oxide surface, CTR shows enhanced photocatalytic bacterial inactivation performance under simulated solar light. As confirmed by the reactive oxygen species production, the generation of superoxide anion (O2[radical dot]−) and hydrogen peroxide (H2O2) is improved. The electrochemical characterization reveals that charge separation in CTR photocatalysis is also promoted. Taken together, the concurrently improved charge separation and surface oxygen reduction activity contribute to an accelerated photocatalytic bacteria inactivation process.
Increased use of graphene materials might lead to their release into the environment. However, only a few studies have investigated the impact of graphene-based materials on green plants. In the present study, effects of graphene on plant roots and shoots after 48 h or 30 days of hydroponic culture were evaluated to determine its phytotoxicity. Results showed that although exposure to graphene (250, 500, 1000 and 1500 mg L−1) significantly improved root elongation, root hair production was impaired. These observations might be associated with graphene induced-oxidative stress (indicated by nitroblue tetrazolium (NBT) and Evans blue staining, malondialdehyde (MDA) estimation, and antioxidant enzyme activity assay). After 30 days of graphene exposure, shoot biomass, chlorophyll content, PSII activity and levels of several nutrient elements (N, K, Ca, Mg, Fe, Zn and Cu) were reduced, indicating that graphene inhibited plant growth and photosynthesis, and caused an imbalance of nutrient homeostasis. Based on these findings, we conclude that graphene has growth-limiting effects on plants, including root hair reduction, oxidative burst, photosynthesis inhibition, and nutritional disorder.
The joint effects of NPs with other chemicals is not fully yet understood along with the joint effects of the particulate and dissolved forms/fractions. The predictability of joint effects is of great importance for environmental risk assessment. Therefore this study aimed at inferring on the predictability of NPs binary mixture toxicity based on their ionic counterparts’ mixtures, and evaluating if the joint toxicity of two forms of the same element (NP and ion) acts as dilution of each other. Effects of individual and mixtures of ZnO and Ag NPs and their respective salts (AgNO3 and ZnCl2) were studied in immobilization and feeding tests using Daphnia magna. NPs mixture toxicity patterns did not mirror their ionic counterparts’ mixture toxicity responses and therefore their prediction should not rely on the available knowledge for regular chemicals. Regarding mixtures from the same element with different forms (NP and ions), both Zn and Ag mixtures showed a deviation from additivity, relying on the interaction between NP and ions. A synergistic effect was depicted when the concentrations of Ag ions increased, while antagonism was observed with AgNP increase in suspension. This is an expected pattern in long term studies due to dissolution, relating fate and toxicity.
In recent years, molybdenum disulfide (MoS2), as a material that shows analogous structure to graphene, has attracted more and more attentions of scientists. Due to its layered structure, special electronic and electrochemical properties, large specific surface area and the potential of surface modification, nano-sized MoS2 is widely used in many fields. In this review, the authors introduce several preparation methods of nano-sized MoS2, mainly including micromechanical cleavage, liquid exfoliation, lithium intercalation, hydrothermal reaction, vapor deposition and thermal decomposition. All these methods possess their own advantages, but at present, there is no good ways to achieve the large-scale production of large-area MoS2 nanosheets with controllable layer number or MoS2 nano-architectures with controllable shape. Apart from the preparation methods, the authors mainly introduce the research progress on the application of nano-sized MoS2 in the fields of optoelectronic devices, catalysis, sensing, energy storage and conversion, and stress the research status of the application in the aspects of electrochemistry and biosensing analysis. In addition, the development direction of nano-sized MoS2 in the future is also been pointed out. According to the present researches, nano-sized MoS2 possesses enormous potential in the fields of energy storage and conversion, sensing analysis, and devices, etc., and it may become a kind of multi-functional material with excellent performance in the wake of graphene. © 2016 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.
Graphene has emerged as a novel green broad-spectrum antibacterial material, with little bacterial resistance and tolerable cytotoxic effect on mammalian cells. It exerts its antibacterial action via physical damages such as direct contact of its sharp edges with bacterial membranes and destructive extraction of lipid molecules. These damages also include wrapping and photothermal ablation mechanisms. Alternatively, chemical damage of bacteria is caused by oxidative stress with the generation of reactive oxygen species and charge transfer. Furthermore, graphene has been used as a support to disperse and stabilize various nanomaterials, such as metals, metal oxides, and polymers, with high antibacterial efficiency due to the synergistic effect. In addition, graphene-based antibiotic drug delivery platforms have been constructed. Due to the superior antibacterial properties and good biocompatibility, graphene-based nanocomposites have a wide range of applications, such as antibacterial packaging, wound dressing, and water disinfection. In this review, we highlight the antibacterial mechanism of graphene and summarize recent advances related to the antibacterial activity of graphene-based materials. Many of the recent application examples are further discussed. We hope that this review provides valuable insight, stimulates broader concerns, and spurs further developments in this promising field.
Hetero-assembling of spherical building blocks with well-defined spatial distribution holds great significance in developing chiral nanostructures. Herein, a strategy for hetero-assembling of gold nanoparticles (AuNPs) was demonstrated using rigid bifacial DNA origami as templates. By tuning the sizes and the fixed location of AuNPs on DNA origami, right-handed and left-handed AuNPs nanostructures were respectively constructed. Gel electrophoresis indicated the formation of the DNA origami- AuNPs complex and transmission electron microscopy (TEM) visually displayed the arrangement of AuNPs in these two chiral structures. The spatial configuration and 3D geometry of AuNPs were further illustrated by the stereographic TEM with tilting angles from ?30° to 30°. This strategy provides a universal approach to construct the asymmetrical 3D geometries, which may have potential applications in biomimicking and nanophotonics. © 2016 Science China Press and Springer-Verlag Berlin Heidelberg