Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The correlation between shape and concentration of silver nanoparticles (AgNPs), their cytotoxicity and formation of reactive oxygen species (ROS) in the presence of electromagnetic fields (EMFs) has been investigated. In addition, the bio-effects caused by the combination of EMFs and graphene nanoparticles (GrNPs) have been also assessed. The AgNPs of three shapes (triangular, spherical and colloidal) and GrNPs were added in high concentrations to the culture of human fibroblasts and exposed to EMF of three different frequencies: 900, 2400 and 7500 MHz. The results demonstrated the dependence of the EMF-induced cytotoxicity on the shape and concentration of AgNPs. The maximal cell killing effect was observed at 900 MHz frequency for NPs of all shapes and concentrations. The highest temperature elevation was observed for GrNPs solution irradiated by EMF of 900 MHz frequency. The exposure to EMF led to significant increase of ROS formation in triangular and colloidal AgNPs solutions. However, no impact of EMF on ROS production was detected for spherical AgNPs. GrNPs demonstrated ROS-protective activity that was dependent on their concentration. Our findings indicate the feasibility to control cytotoxicity of AgNPs by means of EMFs. The effect EMF on the biological activity of AgNPs and GrNPs is reported here for the first time.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The functional healing of skeletal fractures is achieved upon the recovery of weight bearing (Saliev et al., 2019). ...
... -Local, using osteogenic materials like autologous bone marrow, autologous bone, peptide signalling molecules (FGF-2 and PDGFs), morphogenetic factors (BMPs-bone morphogenetic proteins and Wnt proteins) and osteoconductive materials (calcium phosphate, calcium hydroxyapatite, calcium sulphates amongst others) (Einhorn and Gerstenfeld, 2015;Saliev et al., 2019). In particular, BMPs have been extensively investigated and BMP-2 and -7 were also approved by the FDA for some clinical uses. ...
... PEMF has an ability to stimulate cell migration and proliferation, cause changes in cell cycle and differentiation, growth factor expression and DNA replication (Saliev et al., 2019). Moreover, positive local influence on pain reduction is associated with this form of therapy (Ryang We et al., 2013). ...
... A similar [54]. Also, AgNPs could increase ROS production in a shapedependent manner [55]. The highest amount of ROS were produced by human fibroblast cells after treatment with 12.8 nm triangular AgNPs [55]. ...
... Also, AgNPs could increase ROS production in a shapedependent manner [55]. The highest amount of ROS were produced by human fibroblast cells after treatment with 12.8 nm triangular AgNPs [55]. ...
Article
Full-text available
Implant-related infections are an emerging clinical and economic problem. Therefore, we decided to assess potential clinical usefulness and safety of silver orthophosphate microparticles (SOMPs) regarding their shape. We synthesized and then assessed antimicrobial properties and potential cytotoxicity of six shapes of SOMPs (tetrapod, cubes, spheres, tetrahedrons, branched, and rhombic dodecahedron). We found that SOMPs had a high antimicrobial effect; they were more efficient against fungi than bacteria. SOMPs exerted an antimicrobial effect in concentrations not toxic to mammalian cells: human fetal osteoblast (hFOB1.19), osteosarcoma (Saos-2), mouse preosteoblasts (MC3T3-E1), skin fibroblast (HDF), and mouse myoblast (C2C12). At higher concentration SOMPs, induced shape- and concentration-dependent cytotoxicity (according to MTT and BrdU assays). Tetrapod SOMPs had the smallest effect, whereas cubical SOMPs, the highest on cell viability. hFOB1.19 were the most resistant cells and C2C12, the most susceptible ones. We have proven that the induction of oxidative stress and inflammation is involved in the cytotoxic mechanism of SOMPs. After treatment with microparticles, we observed changes in levels of reactive oxygen species, first-line defense antioxidants-superoxide dismutase (SOD1, SOD3), and glutathione peroxidase (GPX4), metalloproteinase (MMP1, MMP3), and NF- κ B protein. Neither cell cycle distribution nor ultrastructure was altered as determined by flow cytometry and transmission electron microscopy, respectively. In conclusion, silver orthophosphate may be a safe and effective antimicrobial agent on the implant surface. Spherical-shaped SOMPs are the most promising for biomedical application.
... However, cytotoxic effects, including the generation of ROS, were found to be concentration-dependent. [135] . Gold has been shown to be a very biocompatible material due to its non-reactivity. ...
Article
Full-text available
Myocardial infarction (MI) represents one of the most prevalent cardiovascular diseases, with a highly relevant and impactful role in public health. Despite the therapeutic advances of the last decades, MI still begets extensive death rates around the world. The pathophysiology of the disease correlates with cardiomyocyte necrosis, caused by an imbalance in the demand of oxygen to cardiac tissues, resulting from obstruction of the coronary flow. To alleviate the severe effects of MI, the use of various biomaterials exhibit vast potential in cardiac repair and regeneration, acting as native extracellular matrices. These hydrogels have been combined with nano sized or functional materials which possess unique electrical, mechanical, and topographical properties that play important roles in regulating phenotypes and the contractile function of cardiomyocytes even in adverse microenvironments. These nano-biomaterials’ differential properties have led to substantial healing on in vivo cardiac injury models by promoting fibrotic scar reduction, hemodynamic function preservation, and benign cardiac remodeling. In this review, we discuss the interplay of the unique physical properties of electrically conductive nano-biomaterials, are able to manipulate the phenotypes and the electrophysiological behavior of cardiomyocytes in vitro, and can enhance heart regeneration in vivo. Consequently, the understanding of the decisive roles of the nano-biomaterials discussed in this review could be useful for designing novel nano-biomaterials in future research for cardiac tissue engineering and regeneration. Statement of Significance This study introduced and deciphered the understanding of the role of multimodal cues in recent advances of electrically conductive nano-biomaterials on cardiac tissue engineering. Compared with other review papers, which mainly describe these studies based on various types of electrically conductive nano-biomaterials, in this review paper we mainly discussed the interplay of the unique physical properties (electrical conductivity, mechanical properties, and topography) of electrically conductive nano-biomaterials, which would allow them to manipulate phenotypes and the electrophysiological behaviour of cardiomyocytes in vitro and to enhance heart regeneration in vivo. Consequently, understanding the decisive roles of the nano-biomaterials discussed in the review could help design novel nano-biomaterials in future research for cardiac tissue engineering and regeneration.
... A large number of reports then looked at the nonthermal effects of exposure to RF on cancer while others dealt with physiological functions [van Rongen et al., 2009;Ghosn et al., 2012Ghosn et al., , 2015, endocrine system, fertility, genotoxicity [Saliev et al., 2019;Vijayalaxmi and Prihoda, 2019], sleep [Danker-Hopfe et al., 2016;Lowden et al., 2019], etc. Many models have been used, ranging from cell cultures and in vivo effects of exposure on laboratory animals to clinical and epidemiological studies. ...
Article
Full-text available
The extremely important use of mobile phones in the world, at all ages of life, including children and adolescents, leads to significant exposure of these populations to electromagnetic waves of radiofrequency. The question, therefore, arises as to whether exposure to these radiofrequencies (RFs) could lead to deleterious effects on the body's biological systems and health. In the current article, we review the effects, in laboratory animals and humans, of exposure to RF on two hormones considered as endocrine markers: melatonin, a neurohormone produced by the pineal gland and cortisol, a glucocorticosteroid synthesized by the adrenal glands. These two hormones are also considered as markers of the circadian system. The literature search was performed using PubMed, Medline, Web of Sciences (ISI Web of Knowledge), Google Scholar, and EMF Portal. From this review on RF effects on cortisol and melatonin, it appears that scientific papers in the literature are conflicting, showing effects, no effects, or inconclusive data. This implies the need for additional research on higher numbers of subjects and with protocols perfectly controlled with follow-up studies to better determine whether the chronic effect of RF on the biological functioning and health of users exists (or not). Bioelectromagnetics. 2021;42:5-17.
... A large number of reports then looked at the nonthermal effects of exposure to RF on cancer while others dealt with physiological functions [van Rongen et al., 2009;Ghosn et al., 2012Ghosn et al., , 2015, endocrine system, fertility, genotoxicity [Saliev et al., 2019;Vijayalaxmi and Prihoda, 2019], sleep [Danker-Hopfe et al., 2016;Lowden et al., 2019], etc. Many models have been used, ranging from cell cultures and in vivo effects of exposure on laboratory animals to clinical and epidemiological studies. ...
Article
The extremely important use of mobile phones in the world, at all ages of life, including children and adolescents, leads to significant exposure of these populations to electromagnetic waves of radiofrequency. The question, therefore, arises as to whether exposure to these radiofrequencies (RFs) could lead to deleterious effects on the body's biological systems and health. In the current article, we review the effects, in laboratory animals and humans, of exposure to RF on two hormones considered as endocrine markers: melatonin, a neurohormone produced by the pineal gland and cortisol, a glucocorticosteroid synthesized by the adrenal glands. These two hormones are also considered as markers of the circadian system. The literature search was performed using PubMed, Medline, Web of Sciences (ISI Web of Knowledge), Google Scholar, and EMF Portal. From this review on RF effects on cortisol and melatonin, it appears that scientific papers in the literature are conflicting, showing effects, no effects, or inconclusive data. This implies the need for additional research on higher numbers of subjects and with protocols perfectly controlled with follow‐up studies to better determine whether the chronic effect of RF on the biological functioning and health of users exists (or not). Bioelectromagnetics. 2021;42:5–17.
... Results from diverse in vitro experimental models indicate that RF can have bio-effects and affect cell viability, depending on the cell type (Wójcik-Piotrowicz et al., 2014) and the electromagnetic parameters applied, such as frequency (Saliev et al., 2019) and exposure time (García-Minguillán López et al., 2019). In the present work, toxicity increased clearly when the two environmental pollutants (BC + RF) acted jointly, compared to the sole action of RF. ...
Article
Environmental factors such as air pollution by particles and/or electromagnetic fields (EMFs) are studied as harmful agents for human health. We analyzed whether the combined action of EMF with fine and coarse black carbon (BC) particles induced cell damage and inflammatory response in RAW 264.7 cell line macrophages exposed to 2.45 GHz in a gigahertz transverse electromagnetic (GTEM) chamber at sub-thermal specific absorption rate (SAR) levels. Radiofrequency (RF) dramatically increased BC-induced toxicity at high doses in the first 24 h and toxicity levels remained high 72 h later for all doses. The increase in macrophage phagocytosis induced after 24 h of RF and the high nitrite levels obtained by stimulation with lipopolysaccharide (LPS) endotoxin 24 and 72 h after radiation exposure suggests a prolongation of the innate and inflammatory immune response. The increase of proinflammatory cytokines tumor necrosis factor-α, after 24 h, and of interleukin-1β and caspase-3, after 72 h, indicated activation of the pro-inflammatory response and the apoptosis pathways through the combined effect of radiation and BC. Our results indicate that the interaction of BC and RF modifies macrophage immune response, activates apoptosis, and accelerates cell toxicity, by which it can activate the induction of hypersensitivity reactions and autoimmune disorders.
... When incubating human gingival fibroblast cells (CRL-2014) with AgNPs, it was found that AgNPs penetrated the cell membrane and localized inside the mitochondria [31]. In additional it was determined that AgNPs induced loss of cell viability and its ability to proliferation in a dose-dependent manner [18,[32][33][34][35]. ...
Article
Full-text available
Novel silver/poly-1-vinyl-1,2,4-triazole nanocomposite materials—possessing antimicrobial activity against Gram-positive and Gram-negative bacteria—have been synthesized and characterized in the solid state and aqueous solution by complex of modern physical-chemical and biologic methods. TEM-monitoring has revealed the main stages of microbial cell (E. coli) destruction by novel nanocomposite. The concept of direct polarized destruction of microbes by nanosilver proposed by the authors allows the relationship between physicochemical and antimicrobial properties of novel nanocomposites. At the same time, it was shown that the nanocomposite was nontoxic to the fibroblast cell culture. Thus, the synthesized nanocomposite combining antibacterial activity against Gram-positive and Gram-negative bacteria as well as the absence of toxic effects on mammalian cells is a promising material for the development of catheters, coatings for medical devices.
... NPs come in many different shapes, sizes and materials, with a common feature that their characteristic length is less than 100 nm. NP types include quantum dots (Michalet et al., 2005), spherical particles (Pankhurst et al., 2003), rod and tube shaped particles (Wong et al., 1997), 2D sheets (Saliev et al., 2019;Zhu et al., 2019), and 3D superlattices (Ji et al., 2019). In the context of biological applications, NPs have been hailed for their ability to target cells of interest, shown most strikingly in targeting cancer cells to deliver drugs (Breunig et al., 2008), improving transfections (Sokolova et al., 2019), silencing genes (Frede et al., 2016;Morgan et al., 2019), or even employing material properties to destroy target cells (Sanhaji et al., 2019), all in an effort to combat disease. ...
Article
Full-text available
Organoids are 3D multicellular constructs that rely on self-organized cell differentiation, patterning and morphogenesis to recapitulate key features of the form and function of tissues and organs of interest. Dynamic changes in these systems are orchestrated by biochemical and mechanical microenvironments, which can be engineered and manipulated to probe their role in developmental and disease mechanisms. In particular, the in vitro investigation of mechanical cues has been the focus of recent research, where mechanical manipulations imparting local as well as large-scale mechanical stresses aim to mimic in vivo tissue deformations which occur through proliferation, folding, invagination, and elongation. However, current in vitro approaches largely impose homogeneous mechanical changes via a host matrix and lack the required positional and directional specificity to mimic the diversity of in vivo scenarios. Thus, while organoids exhibit limited aspects of in vivo morphogenetic events, how local forces are coordinated to enable large-scale changes in tissue architecture remains a difficult question to address using current techniques. Nanoparticles, through their efficient internalization by cells and dispersion through extracellular matrices, have the ability to provide local or global, as well as passive or active modulation of mechanical stresses on organoids and tissues. In this review, we explore how nanoparticles can be used to manipulate matrix and tissue mechanics, and highlight their potential as tools for fate regulation through mechanotransduction in multicellular model systems.
... It is difficult to determine the effect of degree of dispersion and differences in shape on toxicity of GFNs, thus contradictory conclusions may still be drawn from the same cell line treated in different laboratories. The effect of size on GNF toxicity has frequently been investigated in non-phagocytes and adherent cells such as fibroblasts or epithelial cells Lasocka et al. 2018;Saliev et al. 2019;Wu et al. 2018b). Note that the size dependent toxicity of GO flakes might not be applicable to phagocytes, and non-phagocytic suspension cells (Gies and Zou 2017;Yue et al. 2012). ...
Article
Full-text available
Due to its unique physical structure and chemical properties, graphene family nanomaterials (GFNs) and derived commodities have been widely used in commercial products, particularly biomedical applications, which has significantly increased the risk of human exposure. There exists significant evidence that GFNs are accumulated in a number of tissues and organs through different exposure pathways, and further cause toxicity manifested as lesions or functional impairment. Moreover, GFNs can be internalized by varing cell types and induce cytoskeletal disorders, organelle dysfunction, and interact directly with biological macromolecules such as DNA, mRNA and proteins, ultimately resulting in greater rates of cell apoptosis, necrosis and autophagic cell death. The toxicological effect of GFN is closely related to its lateral size, surface structure, functionalization, and propensity to adsorb proteins. Using major data published over the past four years, this review presents and summarizes state of current understanding of GFN toxicology and identifies current deficiencies and challenges. This review aims to help improve evaluation of the biocompatibility of GFNs and provides theoretical guidance for their safe application.
... As an alternative to the light irradiation, CNTs can be exposed to external electromagnetic fields in a non-contact and non-invasive manner. In fact, there is a range of reports on achieving thermal effect using the combination of electromagnetic radiation and graphene-or carbon-based nanoparticles [108,109]. These studies indicated the feasibility of exploiting the CNTs for heating deep-seated tumors in hospital environment. ...
Article
Full-text available
Unique chemical, physical, and biological features of carbon nanotubes make them an ideal candidate for myriad applications in industry and biomedicine. Carbon nanotubes have excellent electrical and thermal conductivity, high biocompatibility, flexibility, resistance to corrosion, nano-size, and a high surface area, which can be tailored and functionalized on demand. This review discusses the progress and main fields of bio-medical applications of carbon nanotubes based on recently-published reports. It encompasses the synthesis of carbon nanotubes and their application for bio-sensing, cancer treatment, hyperthermia induction, antibacterial therapy, and tissue engineering. Other areas of carbon nanotube applications were out of the scope of this review. Special attention has been paid to the problem of the toxicity of carbon nanotubes.
Article
Nanotechnology is spanning multiple fields of study from materials science to computer engineering and drug discovery. Since the early 21st Century, nanotechnology and nano-enabled research have received great attention and governmental funding accompanied with interest to ensure human and environmental safety of engineered nanomaterials (ENMs). Optimal functioning of the cardiovascular (CV) system is of utmost importance for the overall health of the body. Following exposure, ENMs essentially end up in the circulation (at least partially) and hence it is key to assess any associated adverse CV consequences. Accumulating research suggests that exposure to ENMs (different compositions and physicochemical properties) have the capacity to directly and indirectly interact with CV components resulting in adverse events and worsening of CV complications. However, the underlying molecular mechanisms driving these events remains to be elucidated. In this article, we review state-of-art literature on ENM-associated adverse CV responses and discuss the potential underlying molecular mechanisms.
Article
Full-text available
In this study, we aimed to evaluate changes in the acute toxicity of intraperitoneally administered silver nanoparticles (AgNPs) of varying sizes in BALB/c mice. Seven-week-old female BALB/c mice were intraperitoneally administered AgNPs measuring 10, 60, or 100 nm in diameter (0.2 mg/mouse) and then sacrificed 1, 3, or 6 h after treatment. In mice administered 10 nm AgNPs, reduced activity and piloerection were observed at 5 h post administration, and lowered body temperature was observed at 6 h post administration, with histopathological changes of congestion, vacuolation, single cell necrosis, and focal necrosis in the liver; congestion in the spleen; and apoptosis in the thymus cortex. These histopathological changes were not evident following administration of either 60 or 100 nm AgNPs. These results suggested that smaller AgNPs, e.g., those measuring 10 nm in diameter, had higher acute toxicity in mice.
Article
Full-text available
Background Gemcitabine (GEM) is widely used as an anticancer agent in several types of solid tumors. Silver nanoparticles (AgNPs) possess unique cytotoxic features and can induce apoptosis in a variety of cancer cells. In this study, we investigated whether the combination of GEM and AgNPs can exert synergistic cytotoxic effects in the human ovarian cancer cell line A2780. Methods We synthesized AgNPs using resveratrol as a reducing and stabilizing agent. The synthesized nanomaterials were characterized using various analytical techniques. The anticancer effects of a combined treatment with GEM and AgNPs were evaluated using a series of cellular assays. The expression of pro- and antiapoptotic genes was measured using real-time reverse transcription polymerase chain reaction. Apoptosis was confirmed by TUNEL assay. Results In this study, combined treatment with GEM and AgNPs significantly inhibited viability and proliferation in A2780 cells. Moreover, the levels of apoptosis in cells treated with a combination of GEM and AgNPs were significantly higher compared with those in cells treated with GEM or AgNPs alone. Our data suggest that GEM and AgNPs exhibit potent apoptotic activity in human ovarian cancer cells. Combined treatment with GEM and AgNPs showed a significantly higher cytotoxic effect in ovarian cancer cells compared with that induced by either of these agents alone. Conclusion Our study demonstrated that the interaction between GEM and AgNPs was cytotoxic in ovarian cancer cells. Combined treatment with GEM and AgNPs caused increased cytotoxicity and apoptosis in A2780 cells. This treatment may have therapeutic potential as targeted therapy for the treatment of ovarian cancer. To our knowledge, this study could provide evidence that AgNPs can enhance responsiveness to GEM in ovarian cancer cells and that AgNPs can potentially be used as chemosensitizing agents in ovarian cancer therapy.
Article
Full-text available
Objective: Silver nanoparticles (AgNPs) have been extensively studied for their antimicrobial properties, which provide an extensive applicability in dentistry. Because of this increasing interest in AgNPs, the objective of this paper was to review their use in nanocomposites; implant coatings; pre-formulation with antimicrobial activity against cariogenic pathogens, periodontal biofilm, fungal pathogens and endodontic bacteria; and other applications such as treatment of oral cancer and local anesthesia. Recent achievements in the study of the mechanism of action and the most important toxicological aspects are also presented. Methods: Systematic searches were carried out in Web of Science (ISI), Google, PubMed, SciFinder and EspaceNet databases with the keywords "silver nano* or AgNP*" and "dentist* or dental* or odontol*". Results: A total of 155 peer-reviewed articles were reviewed. Most of them were published in the period of 2012-2017, demonstrating that this topic currently represents an important trend in dentistry research. In vitro studies reveal the excellent antimicrobial activity of AgNPs when associated with dental materials such as nanocomposites, acrylic resins, resin co-monomers, adhesives, intracanal medication, and implant coatings. Moreover, AgNPs were demonstrated to be interesting tools in the treatment of oral cancers due to their antitumor properties. Significance: The literature indicates that AgNPs are a promising system with important features such as antimicrobial, anti-inflammatory and antitumor activity, and a potential carrier in sustained drug delivery. However, there are some aspects of the mechanisms of action of AgNPs, and some important toxicological aspects arising from the use of this system that must be completely elucidated.
Article
Full-text available
The plasmonic behavior of size-selected supported silver clusters is studied by surface second harmonic generation spectroscopy for the first time. A blue shift of ~0.2 eV in the plasmon resonance is observed with decreasing cluster size from Ag55 to Ag9. In addition to the general blue shift, also a nonscalable size-dependence is observed in plasmonic behavior of Ag nanoclusters that is attributed to varying structural properties of the clusters. The results are in quantitative agreement with a hybrid theoretical model based on Mie theory and existing DFT calculations.
Article
Full-text available
Silver nanoparticles (AgNPs) induce the production of reactive oxygen species (ROS) and apoptosis. These effects are enhanced by smaller particles. Using live-cell imaging, we show that AgNPs induced ROS production rapidly in a size-dependent manner after exposure of cells to 70-nm and 1-nm AgNPs (AgNPs-70, AgNPs-1), but not AgNO3. Exposure of cells to 5 μg/mL each of AgNPs-70, AgNPs-1 or AgNO3 for 1 h decreased the cell viability by approximately 40%, 100% and 20%, respectively. ROS were rapidly induced after 5 and 60 min by AgNPs-1 and AgNPs-70, respectively, whereas AgNO3 had no detectable effect. ROS production detected using the reporter dichlorodihydrofluorescein was observed in whole cells and mitochondria 5 and 60 min after exposure to AgNPs-1. The present study is the first, to our knowledge, to report the temporal expression and intracellular localization of ROS induced by AgNPs.
Article
Full-text available
Silver nanoparticles (Ag-NP) are one of the fastest growing products in nano-medicine due to their enhanced antibacterial activity at the nanoscale level. In biomedicine, hundreds of products have been coated with Ag-NP. For example, various medical devices include silver, such as surgical instruments, bone implants and wound dressings. After the degradation of these materials, or depending on the coating technique, silver in nanoparticle or ion form can be released and may come into close contact with tissues and cells. Despite incorporation of Ag-NP as an antibacterial agent in different products, the toxicological and biological effects of silver in the human body after long-term and low-concentration exposure are not well understood. In the current study, we investigated the effects of both ionic and nanoparticulate silver on the differentiation of human mesenchymal stem cells (hMSCs) into adipogenic, osteogenic and chondrogenic lineages and on the secretion of the respective differentiation markers adiponectin, osteocalcin and aggrecan. As shown through laser scanning microscopy, Ag-NP with a size of 80 nm (hydrodynamic diameter) were taken up into hMSCs as nanoparticulate material. After 24 h of incubation, these Ag-NP were mainly found in the endo-lysosomal cell compartment as agglomerated material. Cytotoxicity was observed for differentiated or undifferentiated hMSCs treated with high silver concentrations (≥20 µg·mL(-1) Ag-NP; ≥1.5 µg·mL(-1) Ag(+) ions) but not with low-concentration treatments (≤10 µg·mL(-1) Ag-NP; ≤1.0 µg·mL(-1) Ag(+) ions). Subtoxic concentrations of Ag-NP and Ag(+) ions impaired the adipogenic and osteogenic differentiation of hMSCs in a concentration-dependent manner, whereas chondrogenic differentiation was unaffected after 21 d of incubation. In contrast to aggrecan, the inhibitory effect of adipogenic and osteogenic differentiation was confirmed by a decrease in the secretion of specific biomarkers, including adiponectin (adipocytes) and osteocalcin (osteoblasts). Aside from the well-studied antibacterial effect of silver, little is known about the influence of nano-silver on cell differentiation processes. Our results demonstrate that ionic or nanoparticulate silver attenuates the adipogenic and osteogenic differentiation of hMSCs even at non-toxic concentrations. Therefore, more studies are needed to investigate the effects of silver species on cells at low concentrations during long-term treatment.
Article
Full-text available
Biosynthesis of silver nanoparticles using Planomicrobium sp. and to explore the antibacterial activity against food borne pathogenic bacteria Bacillus subtilis, (3053) Klebsiella planticola (2727) Klebsiella pneumoniae (MAA) Serratia nematodiphila (CAA) and Escherichia coli. In the current studies, 1 mM of silver nitrate was added into 100 mL of Planomicrobium sp. culture supernatant. The bioreduction of pure AgNO3 was characterized by UV-visible spectroscopy, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive analysis (EDS), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) analysis. The formation of silver nanoparticles was confirmed by the presence of an absorption peak at 400 nm using UV-visible spectrophotometry. The morphology and size of the silver nanoparticles was monitored by TEM and SEM. Crystal structure was obtained by carrying out X-ray diffraction studies and it showed face centered cubic (FCC) structure. The bactericidal effect of silver nanoparticles was compared based on diameter of inhibition zone in well method. Bacterial sensitivity to nanoparticles a key factor in manufacture the suitable for long life application in food packaging and food safety. Food safety is a worldwide health goal and the food borne diseases get a main disaster on health. Therefore, controlling of bacterial pathogens in food is credit of harms associated to health and safety.
Article
Full-text available
Bovine mastitis is the most costly disease affecting dairy cows and milk production. As Staphylococcus aureus is considered as a major pathogen due to its prevalence in dairy herds, contagious nature of infection, economic impact of treatment and control and its resistance to antimicrobial agents is a well-documented challenge in dairy cows. Therefore, the purpose of this study was to investigate and determine the antibacterial activity of silver nanoparticles against S. aureus isolated from subclinical mastitis cows. The minimum inhibitory concentrations (MIC) distribution of the silver nanoparticles tested for S. aureus field isolates were determined by a broth dilution method. The results show MIC values ranging from 1.25 to 10 µg/ml. The MIC values that inhibited 50 and 90% of the population of the isolates tested of silver nanoparticles were 5 and 10 µg/ml for S. aureus, respectively. In addition, the results of this study demonstrated that the mean time of the antimicrobial action of silver nanoparticles against S. aureus is 7 min. This in vitro result clearly indicates that the silver nanoparticle might have a good activity against S. aureus with mastitis origin.
Article
Full-text available
When light is brought to a standstill, its interaction with gain media increases dramatically due to a singularity in the density of optical states. Concurrently, stopped light engenders an inherent and cavity-free feedback mechanism, similar in effect to the feedback that has been demonstrated and exploited in large-scale disordered media and random lasers. Here we study the spatial, temporal and spectral signatures of lasing in planar gain-enhanced nanoplasmonic structures at near-infrared frequencies and show that the stopped-light feedback mechanism allows for nanolasing without a cavity. We reveal that in the absence of cavity-induced feedback, the subwavelength lasing mode forms dynamically as a phase-locked superposition of quasi dispersion-free waveguide modes. This mechanism proves remarkably robust against interface roughness and offers a new route towards nanolasing, the experimental realization of ultra-thin surface emitting lasers, and cavity-free active quantum plasmonics.
Article
Full-text available
In order to improve its biological properties, graphene oxide can be modified with hydrophilic polymers. Therefore, in this study, the surface of graphene oxide was modified with polyethylene glycol and albumin by covalent methods. In the subsequent step, paclitaxel which is a hydrophobic anticancer drug was loaded onto the surface of the functionalized graphene by π–π interactions. The synthesis of the nanocarrier and its interaction with paclitaxel were evaluated by FT-IR, CD, TEM, UV, AFM, DLS and fluorescence experiments. Release of the loaded drug from albumin–graphene conjugate was investigated at pH 5.4, 6.8 and 7.4.
Article
Full-text available
Silver Nanoparticles (AgNPs), the real silver bullet, are known to have good antibacterial properties against pathogenic microorganisms. In the present study AgNPs were prepared from extracellular filtrate of Aspergillus niger. Characterization of AgNPs by UV-Vis spectrum reveals specific surface plasmon resonance at peak 416 nm; TEM photographs revealed the size of the AgNPs to be 20–55 nm. Average diameter of the produced AgNPs was found to be 73 nm with a zeta potential that was −24 mV using Malvern Zetasizer. SEM micrographs showed AgNPs to be spherical with smooth morphology. EDS revealed the presence of pure metallic AgNPs along with carbon and oxygen signatures. Of the different concentrations (0, 2.5, 5, 10, and 15 íµí¼‡g/mL) used 10 íµí¼‡g/mL were sufficient to inhibit 10 7 CFU/mL of E. coli. ROS production was measured using DCFH-DA method and the the free radical generation effect of AgNPs on bacterial growth inhibition was investigated by ESR spectroscopy. This paper not only deals with the damage inflicted on microorganisms by AgNPs but also induces cell death through the production of ROS released by AgNPs and also growth kinetics of E. coli supplemented with AgNPs produced by A. niger.
Article
Full-text available
Silver nanoparticles (AgNPs) are currently one of the most manufactured nanomaterials. A wide range of toxicity studies have been performed on various AgNPs, but these studies report a high variation in toxicity and often lack proper particle characterization. The aim of this study was to investigate size- and coating-dependent toxicity of thoroughly characterized AgNPs following exposure of human lung cells and to explore the mechanisms of toxicity. BEAS-2B cells were exposed to citrate coated AgNPs of different primary particle sizes (10, 40 and 75 nm) as well as to 10 nm PVP coated and 50 nm uncoated AgNPs. The particle agglomeration in cell medium was investigated by photon cross correlation spectroscopy (PCCS); cell viability by LDH and Alamar Blue assay; ROS induction by DCFH-DA assay; genotoxicity by alkaline comet assay and gammaH2AX foci formation; uptake and intracellular localization by transmission electron microscopy (TEM); and cellular dose as well as Ag release by atomic absorption spectroscopy (AAS). The results showed cytotoxicity only of the 10 nm particles independent of surface coating. In contrast, all AgNPs tested caused an increase in overall DNA damage after 24 h assessed by the comet assay, suggesting independent mechanisms for cytotoxicity and DNA damage. However, there was no gammaH2AX foci formation and no increased production of intracellular reactive oxygen species (ROS). The reasons for the higher toxicity of the 10 nm particles were explored by investigating particle agglomeration in cell medium, cellular uptake, intracellular localization and Ag release. Despite different agglomeration patterns, there was no evident difference in the uptake or intracellular localization of the citrate and PVP coated AgNPs. However, the 10 nm particles released significantly more Ag compared with all other AgNPs (approx. 24 wt% vs. 4-7 wt%) following 24 h in cell medium. The released fraction in cell medium did not induce any cytotoxicity, thus implying that intracellular Ag release was responsible for the toxicity. This study shows that small AgNPs (10 nm) are cytotoxic for human lung cells and that the toxicity observed is associated with the rate of intracellular Ag release, a 'Trojan horse' effect.
Article
Full-text available
In this report, we have designed a simple and efficient green chemistry approach for the synthesis of colloidal silver nanoparticles (b-AgNPs) that is formed by the reduction of silver nitrate (AgNO3) solution using Olax scandens leaf extract. The colloidal b-AgNPs, characterized by various physico-chemical techniques exhibit multifunctional biological activities (4-in-1 system). Firstly, bio-synthesized silver nanoparticles (b-AgNPs) shows enhanced antibacterial activity compared to chemically synthesize silver nanoparticles (c-AgNPs). Secondly, b-AgNPs show anti-cancer activities to different cancer cells (A549: human lung cancer cell lines, B16: mouse melanoma cell line & MCF7: human breast cancer cells) (anti-cancer). Thirdly, these nanoparticles are biocompatible to rat cardiomyoblast normal cell line (H9C2), human umbilical vein endothelial cells (HUVEC) and Chinese hamster ovary cells (CHO) which indicates the future application of b-AgNPs as drug delivery vehicle. Finally, the bio-synthesized AgNPs show bright red fluorescence inside the cells that could be utilized to detect the localization of drug molecules inside the cancer cells (a diagnostic approach). All results together demonstrate the multifunctional biological activities of bio-synthesized AgNPs (4-in-1 system) that could be applied as (i) anti-bacterial & (ii) anti-cancer agent, (iii) drug delivery vehicle, and (iv) imaging facilitator. To the best of our knowledge, there is not a single report of biosynthesized AgNPs that demonstrates the versatile applications (4-in-1 system) towards various biomedical applications. Additionally, a plausible mechanistic approach has been explored for the synthesis of b-AgNPs and its anti-bacterial as well as anti-cancer activity. We strongly believe that bio-synthesized AgNPs will open a new direction towards various biomedical applications in near future.
Article
Full-text available
In this work, graphene nanoribbons and nanoplatelets were investigated as contrast agents for photoacoustic and thermoacoustic tomography (PAT and TAT). We show that oxidized single- and multi-walled graphene oxide nanoribbons (O-SWGNRs, O-MWGNRs) exhibit approximately 5–10 fold signal enhancement for PAT in comparison to blood at the wavelength of 755 nm, and approximately 10–28% signal enhancement for TAT in comparison to deionized (DI) water at 3 GHz. Oxidized graphite microparticles (O-GMPs) and exfoliated graphene oxide nanoplatelets (O-GNPs) show no significant signal enhancement for PAT, and approximately 12–29% signal enhancement for TAT. These results indicate that O-GNRs show promise as multi-modal PAT and TAT contrast agents, and that O-GNPs are suitable contrast agents for TAT.
Article
Full-text available
A dual-targeting drug delivery and pH-sensitive controlled release system based on multi-functionalized graphene oxide (GO) was established in order to enhance the effect of targeted drug delivery and realize intelligently controlled release. A superparamagnetic GO–Fe3O4 nanohybrid was firstly prepared via a simple and effective chemical precipitation method. Then folic acid, a targeting agent toward some tumor cells, was conjugated onto Fe3O4nanoparticlesvia the chemical linkage with amino groups of the 3-aminopropyl triethoxysilane (APS) modified superparamagnetic GO–Fe3O4 nanohybrid, to give the multi-functionalized GO. Doxorubicin hydrochloride (Dox) as an anti-tumor drug model was loaded onto the surface of this multi-functionalized GO via π–π stacking. The drug loading capacity of this multi-functionalized GO is as high as 0.387 mg mg−1 and the drug release depends strongly on pH values. Cell uptake studies were carried out using fluorescein isothiocyanate labeled or Dox loaded multi-functionalized GO to evaluate their targeted delivery property and toxicity to tumor cells. The results show that this multi-functionalized GO has potential applications for targeted delivery and the controlled release of anticancer drugs.
Article
Full-text available
The use of silver nanoparticles has become more widespread in our society. While many believe that silver can be extremely useful in clinical medicine, firm evidence is still lacking. Thus, we present here a review of their current use in clinical medicine.
Article
Full-text available
Abstract Nanoparticulate silver coatings for orthopaedic implants promise to decrease postoperative infection rates. However, silver-induced cytotoxicity on bone cells has not been investigated in detail. This study investigated the cytotoxic effects of silver nano- and microparticles and Ag(+) on osteoblasts (OBs) and osteoclasts (OCs) and correlated their effects with the antibacterial efficacy on Staphylococcus epidermidis. Silver nanoparticles (50 nm) exhibited strong cytotoxic effects on OBs and OCs. Weak cytotoxic effects were observed for silver microparticles (3 μm). The cytotoxicity was primarily mediated by a size-dependent release of Ag(+). Antibacterial effects occurred at Ag(+) concentrations that were 2-4 times higher than those inducing cytotoxic effects. Such adverse effects on OB and OC survival may have deleterious effects on the biocompatibility of orthopaedic implants. Our study represents an important step toward the detailed investigation of orthopaedic implant with nanoparticulate silver coatings prior to their widespread clinical usage.
Article
Full-text available
In this study, the conditions and mechanism of antibacterial activity of hydrophilic polymer coated silver nanoparticles (AgNPs) against E. coli O157:H7 (CMCC44828) as model pathogen was studied. The AgNPs were coated with amphiphilic polymer that introduced carboxyl groups on the surface to make it water-soluble. The AgNPs were exposed to various treatment conditions of pH and temperature before these were combined with the E. coli. The mechanism of the antibacterial activity was studied through the formation of reactive oxygen species (ROS) that was later suppressed with antioxidant to establish correlation with the AgNPs antimicrobial activity. Studies were carried out at both anaerobic and aerobic conditions. The results indicated that 5 mg/L AgNPs inhibited ~50% of the growth of 10(6) colony forming units per milliliter (cfu/mL) E. coli cells in liquid Luria-Bertani (LB) medium. This dose-dependent antimicrobial activity was higher at increased temperature (37°C) but was lower when the AgNPs were treated with acid at pH 2 before exposure to the bacteria. It was also established that the conditions of higher antimicrobial effect generated more ROS that was dependent on the presence of oxygen. The antibacterial activity was suppressed in the presence of an antioxidant.
Article
Water-soluble ligand protected optically active silver nanostructures were synthesised in a one-step reduction and capping process mediated by thiol-containing biomolecules. The synthesis was performed successfully with D- and L-cysteine and L-glutathione. The chiroptical properties of the obtained nanostructures were investigated by circular dichroism spectroscopy in the ultraviolet and visible wavelength range. They exhibit a g-value of up to 0.7%, which is about one order of magnitude larger compared to particles prepared by citrate reduction followed by a ligand exchange reaction. The structure and composition of the prepared materials were characterised by transmission electron microscopy, energy-dispersive X-ray and X-ray photoelectron spectroscopy. Although these structures do not have a chiral geometry, they show mirror image g-values when capped with D- and L-cysteine. This indicates that the underlying chirality transfer mechanism is based on an electric field polarisation process.
Article
Antimicrobial cotton textiles were fabricated via green synthesis of silver nanoparticles (AgNPs) from silver nitrate, using whey protein isolate (WPI) as both reducing agent and stabilizer. Natural tannin-rich extract from Xylocarpus granatum bark (XGBE) was used to form insoluble complexes with the WPI through hydrogen bonding and hydrophobic forces. Cotton fabrics were coated using one-step padding of the AgNP/WPI/XGBE mixture, followed by air drying. Both WPI and XGBE served as an excellent natural binder for AgNPs with cotton. Transmission electron microcopy showed the AgNPs to be almost spherical, with a mean diameter of 31 nm. Antimicrobial treatment did not significantly alter the original color of the fabrics at low AgNPs loadings. The coated fabrics showed strong and durable antibacterial activity against Staphylococcus aureus and Escherichia coli, with 99.99% bacterial reduction. Treatment with only 50 ppm of silver nitrate and WPI maintained more than 90% bacterial reduction after 50 washing cycles. In a test of antifungal properties, at least 203 mg silver per kilogram of fabric was required to suppress the growth of Aspergillus niger. In-vitro cytotoxicity testing demonstrated the antimicrobial treated fabrics to be non-toxic to L929 cells. Antimicrobial treatment did not have significant negative effects on the drapeability and tearing strength of the fabrics. This approach is very attractive in terms of the safety and biocompatibility of the raw materials, the simplicity of the synthesis and the coating process, and the antimicrobial effectiveness of the treated fabrics.
Article
Oral cavity is a gateway to the entire body and protection of this gateway is a major goal in dentistry. Plaque biofilm is a major cause of majority of dental diseases and although various biomaterials have been applied for their cure, limitations pertaining to the material properties prevent achievement of desired outcomes. Nanoparticle applications have become useful tools for various dental applications in endodontics, periodontics, restorative dentistry, orthodontics and oral cancers. Off these, silver nanoparticles (AgNPs) have been used in medicine and dentistry due to its antimicrobial properties. AgNPs have been incorporated into biomaterials in order to prevent or reduce biofilm formation. Due to greater surface to volume ratio and small particle size, they possess excellent antimicrobial action without affecting the mechanical properties of the material. This unique property of AgNPs makes these materials as fillers of choice in different biomaterials whereby they play a vital role in improving the properties. This review aims to discuss the influence of addition of AgNPs to various biomaterials used in different dental applications.
Article
In this study, silver nanoparticles were synthesized (AgNPs) using aqueous rhizome extract of Acorus calamus (ACRE) and evaluated their in vitro anticancer activity and in vivo toxicity in a Wistar rat model. The synthesized AgNPs showed good catalytic activity against different organic pollutant dyes. In vitro cytotoxic effects of AgNPs were assessed in Hep2, COLO 205 and SH-SY5Y cells using MTT assay. Further, the apoptotic changes induced by AgNPs in more susceptible Hep2 cells were observed through AO/EB, DCFH-DA, Rhodamine 123, PI/DAPI staining, oxidative stress markers and Western blotting. In vivo toxicity study revealed substantial alterations in the levels of serum biochemical markers including AST, ALT, LDH and inflammatory markers such as TNF-α and IL-6 on day 29 when rats treated with AgNPs as compared to control, however, these levels were restored to normal at the end of washout period on day 89. No remarkable changes were observed in liver oxidative stress enzymes. ICP-OES analysis indicated bio-distribution of silver in spleen (5.67 μg/g) and liver (4.98 μg/g) in rats treated with 10 mg/kg b.w of AgNPs on day 29 and elimination of silver from all organs was observed at the end of washout period on day 89. Histopathological analysis revealed no significant changes in kidney, spleen, lungs, heart, testis and brain with 5 and 10 mg/kg b.w of AgNP. However, 10 mg/kg b.w of AgNPs showed moderate degree of cell swelling and vacuolar degeneration in liver and these alterations were reverted back to normal at the end of washout period. Findings from this study signify green synthesized AgNPs at low concentrations might be useful in many ways with ecofriendly nature.
Article
The present study explored the mechanism of cytotoxic and genotoxic effects of AgNPs on a primary culture of mouse Sertoli cells in vitro. To understand the possible molecular mechanisms of testicular lesions following exposure to AgNPs, isolated Sertoli cells were exposed to 5, 10, or 15 μg/ml. DNA damage in the Comet assay and apoptosis in the TUNEL assay were evaluated. The mRNA expression of p53 and bcl-2 genes and their proteins involved in apoptosis was also investigated. The antioxidant status of treated Sertoli cells was determined by measuring catalase (CAT), glutathione peroxidase (GPX-1) and superoxide dismutase (SOD-1) using qPCR. The superoxide anions were detected using the nitroblue tetrazolium (NBT) reduction assay. Results indicated that AgNP exposure causes increased oxidative stress levels. The activation of p53, repression of bcl-2 and reduction of endogenous antioxidant enzymes were also involved in these mechanistic pathways, leading to reduced cell numbers and cell detachment.
Article
Graphene oxide-gold nanoparticle (AuNP@GO) hybrids were fabricated in water dispersions of graphene oxide (GO) and Au precursor completely free of stabilizing agents by UV-light irradiation. Gold nanoparticles (AuNP) nucleation, growth, and stabilization mechanisms at the surface of GO are discussed on the basis of UV-Vis, Raman, IR, and X-Ray photo-spectroscopy studies. The analyses of AuNP@GO hybrids by transmission electron microscopy (TEM), thermo gravimetric (TGA) and electrochemical tests exhibit outstanding chemical, thermal and electrochemical stabilities. Thus, AuNP@GO biosensing platforms were fabricated for surface enhanced Raman spectroscopy (SERS) detection of Crystal Violet (CV) a SERS standard molecule, and in a different set of experiments, for flavin adenine dinucleotide (FAD) a flavoprotein coenzyme that plays an important role in many oxidoreductase and reversible redox conversions in biochemical reactions. AuNP@GO hybrids synthesized by using UV light irradiation show exceptional stability and high intensification of the Raman signals exhibiting high potential as biomedical probes for detection, monitoring, and diagnosis of medical diseases.
Article
In literature, varying and sometimes conflicting effects of physicochemical properties of NPs are reported on their uptake and effects in organisms. To address this, small and medium sized (20 and 50 nm) AgNPs with specified different surface coating/charges were synthesized and used to systematically assess effects of NP-properties on their uptake and effects in vitro. AgNPs were fully characterized for charge and size distribution in both water and test media. Macrophage cells (RAW 264.7) were exposed to these AgNPs at different concentrations (0 - 200 µg/mL). Uptake dynamics, cell viability, induction of tumor necrosis factor (TNF)-α, adenosine triphosphate (ATP) production and reactive oxygen species (ROS) generation were assessed. Microscopic imaging of living exposed cells showed rapid uptake and subcellular cytoplasmic accumulation of AgNPs. Exposure to the tested AgNPs resulted in reduced overall viability. Influence of both size and surface coating (charge) was demonstrated, with the 20 nm sized AgNPs and BSA coated (negatively charged) AgNPs being slightly more toxic. On specific mechanisms of toxicity (TNF-α and ROS production) however, the AgNPs differed to a larger extent. The highest induction of TNF-α was found in cells exposed to the negatively charged AgNP_BSA, both sizes (80x higher than control). ROS induction was only significant with the 20 nm positively charged AgNP_Chit.
Article
The sustained extensive research on graphene and its derivatives in the last decade portrayed its significance in the field of material science and carved its own niche in nanotechnology. Starting from the simple pencil, the role of graphene now extends to a lifesaver through innovations in nanomedicine specifically the early detection of abnormalities and efficient treatments. Graphene has the potential to satisfy the nanotechnological concepts of personalized and regenerative medicine for a disease-free future. The functionalization techniques ameliorate graphene for improved solubility, stability, loading capacity, etc. which makes it an ideal nanosystem for theranostic applications such as biosensing, drug delivery, gene therapy, bioimaging, phototherapy and hybrid theranostics. In addition, due to its electrically tunable surface chemistry, maximal surface-to-volume ratio, easy functionalization capacity and mechanical robustness, graphene gained enormous attention in tissue engineering specifically in cardiac, nerve, bone, skin and stem cells. This review focusses on the recent developments in graphene-based nanotheranostics and tissue engineering, which reveals the hidden potential of modern medical notions in efficiently handling the variety of abnormalities. Moreover, it raises the necessity of successful therapeutic systems to transfer from bench-to-bedside through clinical trials to enhance the current treatment scenario.
Article
Cytotoxicity evaluation of hemocytes (lysosomal membrane stability [LMS] assay) from Mytilus galloprovincialis Lamarck, exposed to a sublethal dose (100 µg/L) of two size of silver nanoparticles (AgNP: < 50 nm and < 100 nm) - prior to and after inhibition of potential uptake pathways (i.e., clathrin- and caveolae-mediated endocytosis) within different times of exposure (3, 6, 12 hr) - showed that there was a significant cytotoxic effect on immune cells of mussels exposed for different times to either AgNP size (p < 0.01); the greater effect was with the smaller size. However, hemocytes seemed more sensitive to the larger AgNP after clathrin-mediated endocytosis was blocked (p < 0.01); this was not so with inhibition of caveolae-mediated endocytosis. Dimethyl-sulfoxide (DMSO) did not impart a carrier-mediated effect despite an enhanced cytotoxicity when DMSO was present with AgNP. From these results, it is concluded the immunotoxicity of AgNP in mussels was size- as well as length of exposure-dependent. It was also clear that nanoparticles (NP) internalization mechanisms were a major factor underlying any toxicity.
Article
In order to investigate new effective and inexpensive nano-therapeutic approach for P. aeruginosa, staphylococcus aureus and coagulase negative staphylococci (CoNS), the present study reports an eco-friendly process for rapid synthesis of silver nanoparticles (Ag-NPs) using aqueous leaf extract of Corchorus Capsularis (CRCP). Formation of stable Ag-NPs at different time intervals gives mostly spherical particles with diameters ranging from 5 to 45 nm. The resulting Ag-NPs were characterized using Ultraviolet visible (UV – Vis) spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Diffraction (XRD) analysis, Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray analysis (EDX). XRD study shows that the particles are crystalline in nature with face centered cubic geometry. TEM studies show the formation of Ag-NPs with average size of 20.52 nm. The antimicrobial activity of the synthesized Ag-NPs was investigated against multi drug resistant (MDR) P. aeruginosa, Staphylococcus aureus and CoNS isolates from post-surgical wound infections. The present study suggests that Ag-NPs synthesized from aqueous leaf extract of CRCP shows significant antibacterial potential against MDR isolates from post-surgical wound infections.
Article
The extinction spectra of size-selected, supported Ag20 and Ag55 clusters have been measured with surface cavity ring-down (s-CRD) spectroscopy under ultra-high vac- uum (UHV) conditions. A single plasmonic resonance around 3.2 eV is observed. The reaction with benzenethiol shifts the localized surface plasmon resonance (LSPR) by ≈ 0.3 eV to lower energies, which is attributed to an increased dielectric function of the surrounding medium, as well as a reduction of the free electron density inside the silver clusters. The time dependence of the LSPR redshift under exposure to benzenethiol has a double exponential behavior. A rapid redshift is caused by chemisorption of ben- zenethiol from the gasphase via the formation of a sulfur-silver-bond, whereas a slow redshift is caused by additional physisorption of benzenethiol. Comparative studies with benzene, which do not show any chemisorption but show physisorption character on silver, reveal, that ≈ 0.2 eV of the overall redshift can be attributed to an increased dielectric constant of the surrounding medium, whereas a reduction of the free electron density accounts for ≈ 0.1 eV of the observed redshift.
Article
Many types of nanoparticles (NPS) are tested for use in cancer therapy. In recent years also graphene and graphene-based nanomaterials due to their unique physical, chemical and mechanical properties, have become an attractive nanoparticles in cancer therapy. Graphene based nanomaterials as an anticancer therapeutics can be applied in photothermal therapy, as a drug carrier but also as nano-drugs by themselves. In this review, we present an overview of current developments in the applications of graphene in anticancer therapy, along with a brief discussion on the challenges and prospects for future research in this field. The following review describes only in vitro anticancer studies.
Article
Human endogenous retrovirus (HERV) sequences make up ~8% of the human genome and increased expression of some HERV proteins has been observed in various pathologies including leukaemia and multiple sclerosis. However, little is known about the function of these HERV proteins or environmental factors which regulate their expression. Silver nanoparticles (AgNPs) are used very extensively as antimicrobials and antivirals in numerous consumer products although their effect on the expression of HERV gene products is unknown. Cell proliferation and cell toxicity assays were carried out on human acute T lymphoblastic leukaemia (MOLT-4) and Fanconi anaemia associated acute myeloid leukaemia (FA-AML1) cells treated with two different sizes of AgNPs (7nm and 50nm diameter). Reverse-transcriptase polymerase chain reaction and western blotting were then used to the assess expression of HERV-W syncytin-1 mRNA and protein in these cells. FA-AML1 cells were more sensitive overall than MOLT-4 to treatment with the smaller 7nm sized AgNp’s being the most toxic in these cells. MOLT-4 cell were more resistant and showed no evidence of differential toxicity to the different sized particles. Syncytin-1 mRNA and protein were induced by both 7 and 50nm AgNPs in both cell types yet with different kinetics. In summary, the observation that AgNPs induce expression of syncytin-1 in FA-AML1 and MOLT-4 cells at doses as little as 5 µg/ml is grounds for concern since this protein is up-regulated in both malignant and neurodegenerative diseases. Considering the widespread use of AgNPs in the environment it is clear that their ability to induce syncytin-1 should be investigated further in other cell types.
Article
In view of potential biomedical application of the noble metal nanoparticles, we report a size controlled yet simple and green synthesis of resveratrol stabilized silver and gold nanoparticles having low polydispersity of size. Here, resveratrol plays two simultaneous roles, reducing the metal ions and providing efficient capping of the small nanoparticles. This gives rise to specific size of silver and gold nanoparticles at specific ratios of metal to resveratrol. The particles have been characterized by XRD and transmission electron microscopy. The nanoparticle sols are stable for months. The UV Visible absorption spectra of the silver sol show the plasmon peak of spherical nanoparticles, presence of which is further reflected in the TEM images. Size of the silver particles obtained is in between 11 to 21 nm depending on the ratio of resveratrol to metal ion used. Resveratrol capped silver nanoparticles exhibit high antibacterial activity against Gram negative wild type E coli BW (25113). The minimum inhibitory concentration (MIC) of nano-silver against the bacterium has been estimated to be 6.48 μg/ml, which is significantly lower than that reported in some earlier as well as recent publications. Reaction of gold ions with resveratrol, on the other hand, produces gold nanoparticles of sizes varying from 7 to 29 nm at different ratios of resveratrol to the metal ions. Particles with higher size and aspect ratio are formed at lower concentration of the capping agent whereas particles with very small size and pseudo-spherical morphology are formed at higher capping concentration. Difference in the formation kinetics of silver and gold nanoparticles has been attributed to the different growth mechanisms in the two cases. Possible modes of anchorage of resveratrol to silver nanoparticles have been investigated using surface enhanced resonance Raman spectroscopy (SERS) which shows that the silver nanoparticles are capped by resveratrol molecule primarily through O–Ag linkages of the p-OH aromatic ring. This, in turn, demonstrates the feasibility of using these nanoparticles as SERS templates.
Article
Aims: Silver nanoparticles (AgNPs) have emerged as an important class of nanomaterials with a wide range of industrial and medical applications. The assessment of AgNPs' biological effects in the human organism is therefore essential to evaluate the impact of these nanomaterials in public health and reassure the ratio benefit/risk. In the present study, the effect of polyvinyl pyrrolidone (PVP)-coated AgNPs with distinct sizes (10 and 50 nm) on neu-trophils' oxidative burst and toxicity were tested. Main methods: The effect of AgNPs on human neutrophils viability was evaluated by trypan blue, neutral red and propidium iodide methods. The measurement of neutrophils' oxidative burst was performed using the probe dihydrorhodamine 123. The cytomorphological alterations of human neutrophils exposed to AgNPs were evaluated by optical microscopy and transmission electron microscopy. Key findings: It was observed that PVP-coated AgNPs are toxic to human neutrophils being the 10 nm AgNPs more toxic than the 50 nm AgNPs. The smallest AgNPs lead to membrane damage, impaired lysosomal activity and induce neutrophils' oxidative burst. Despite the production of reactive species, the toxicity of AgNPs is not NADPH oxidase-dependent. Significance: These data indicate that AgNPs are toxic to human neutrophils in concentration-, time-and size-dependent manner, but independent of NADPH oxidase activation.
Article
Graphene oxide nanosheet (GOns) with sharp edges was synthesized using controlled pyrolysis of citric acid. Scanning electron, as well as atomic force microscopy of the sample confirmed the formation of multilayered GOns with an average sheet length of 150nm. X-ray diffraction pattern and Raman spectra also confirmed the formation of GOns. Furthermore, GOns was successfully functionalized (FGOns) by cross-linking with a small protein bovine α-lactalbumin (BLA). The crosslinking of protein with GOns in FGOns was confirmed by infrared spectroscopy, and the conformational change of BLA was observed by fluorescence, as well as circular dichroism spectroscopy. When applied to human erythrocytes, GOns demonstrated profound hemolysis; however, such hemolytic effect was drastically reduced by FGOns. To evaluate the potential biomedical application of FGOns, the cytotoxicity of the sample was also assessed. The administration of both GOns and FGOns in breast cancer cells MCF-7 and MDAMB-231 demonstrated more than 88% cell death within 24h and such cytotoxicity against cancer cells was caused due to the generation of reactive oxygen species (ROS), as revealed from the N-acetyl-l-cysteine (NAC, a ROS-inhibitor)-based assay. FGOns demonstrated excellent biocompatibility against normal cells such as HaCaT and 3T3 compared to GOns that demonstrated dose-dependent toxicity. Moreover, FGOns demonstrated more efficient cellular uptake than GOns by cancer cells. Therefore, our present study demonstrated that the functionalization of GOns using small protein could improve its biocompatibility multifold and such strategy might represent wide opportunity to use GO like nanomaterial safely in various biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.
Article
Current treatments for bone loss injuries involve autologous and allogenic bone grafts, metal alloys and ceramics. Although these therapies have proved useful, they suffer from inherent challenges, and hence, an adequate bone replacement therapy has not yet been found. We hypothesize that graphene may be a useful nanoscaffold for mesenchymal stem cells and will promote proliferation and differentiation into bone progenitor cells. In this study, we evaluate graphene, a biocompatible inert nanomaterial, for its effect on in vitro growth and differentiation of goat adult mesenchymal stem cells. Cell proliferation and differentiation are compared between polystyrene-coated tissue culture plates and graphene-coated plates. Graphitic materials are cytocompatible and support cell adhesion and proliferation. Importantly, cells seeded on to oxidized graphene films undergo osteogenic differentiation in fetal bovine serum-containing medium without the addition of any glucocorticoid or specific growth factors. These findings support graphene's potential to act as an osteoinducer and a vehicle to deliver mesenchymal stem cells, and suggest that the combination of graphene and goat mesenchymal stem cells provides a promising construct for bone tissue engineering.
Article
Nanomaterials offer interesting physicochemical and biological properties for biomedical applications due to their small size, large surface area and ability to interface/interact with the cells/tissues. Graphene-based nanomaterials are fast emerging as "two-dimensional wonder materials" due to their unique structure, excellent mechanical, optical and electrical properties and have been exploited in electronics and other fields. Emerging trends show that their exceptional properties can be exploited for biomedical applications, especially in drug delivery and tissue engineering. This article presents comprehensive review of various types and properties of graphene family nanomaterials. We further highlight how these properties are being exploited for drug delivery and tissue engineering applications.
Article
Silver nanoparticles (AgNPs) are today one of the most commonly used nanomaterials both in fundamental medical sciences and clinical practice. These nanoparticles are also incorporated into many commercial products and widely available to general population. However, recent reports have linked silver nanomaterials to programmed cell death, and increased cytotoxicity in certain conditions. This short review focuses on the recent findings regarding molecular interactions of silver nanoparticles with living cells and tissues. Potential immunomodulatory effects of AgNPs, as well as recent toxicity concerns are also discussed. Finally, we also describe recent public and government efforts to monitor and control the use and availability of silver nanomaterials used as dietary supplements in some countries.
Article
The potential of graphene as a mesenchymal stem cell (MSC) culture substrate to promote cardiomyogenic differentiation is demonstrated. Graphene exhibits no sign of cytotoxicity for stem cell culture. MSCs are committed toward cardiomyogenic lineage by simply culturing them on graphene. This may be attributed, at least partially, to the regulation of expression levels of extracellular matrix and signaling molecules.
Article
Dental caries is a very infectious disease; in humans, 95% of the worldwide population is affected. The microorganism associated with dental caries is Streptococcus mutans (S. mutans). Although several mechanisms for its control have been used, its prevalence and incidence are still high. New alternatives are silver nanoparticles due to their antibacterial effect. In this work, we determined the antibacterial effect of silver nanoparticles on S. mutans. Three sizes of silver nanoparticles were used to find minimum inhibitory concentrations (MIC) in S. mutans using reference and clinical stocks. Kruskal–Wallis and U of Mann–Whitney statistical tests were applied. We found bactericidal effect for the three groups, with significant statistical differences between them. Our results agree with those already reported by several authors. This study concludes that silver nanoparticles present antibacterial activity on S. mutans and this property is better when the particle size is diminished.
Article
The density of states (DOS) and the optical conductivity of graphene is calculated in the presence of a perpendicular magnetic field and where scattering on charged and short-range impurities is included. The standard Kubo formula is employed where the self-energy induced by impurity scattering and the Green’s function are calculated self-consistently including inter-Landau level (LL) coupling and screening effects. It is found that the scattering from those two types of impurities results in a symmetric LL broadening and asymmetric inter-LL coupling renormalizes the LL positions to lower energy. The peak position and intensity of the magneto-optical conductivity depends on the filling factor and the broadened DOS. Good agreement is found with recent cyclotron resonance measurements.
Article
Graphene is a two-dimensional (2D) material with over 100-fold anisotropy of heat flow between the in-plane and out-of-plane directions. High in-plane thermal conductivity is due to covalent sp 2bonding between carbon atoms, whereas out-of-plane heat flow is limited by weak van der Waals coupling. Herein, we review the thermal properties of graphene, including its specific heat and thermal conductivity (from diffusive to ballistic limits) and the influence of substrates, defects, and other atomic modifications. We also highlight practical applications in which the thermal properties of graphene play a role. For instance, graphene transistors and interconnects benefit from the high in-plane thermal conductivity, up to a certain channel length. However, weak thermal coupling with substrates implies that interfaces and contacts remain significant dissipation bottlenecks. Heat flow in graphene or graphene composites could also be tunable through a variety of means, including phonon scattering by substrates, edges, or interfaces. Ultimately, the unusual thermal properties of graphene stem from its 2D nature, forming a rich playground for new discoveries of heat-flow physics and potentially leading to novel thermal management applications.
Article
Silver nano-clusters (NCs) were incorporated into organic light emitting diodes (OLED) and solar cells by means of thermal evaporation. Silver NCs enhance the efficiency of both OLEDs and polymer solar cells under tailored device architecture. In tris-(8-hydroxyquinoline) aluminum (Alq(3)) based small molecule OLEDs, silver NCs were deposited under the Al cathode. The electron injection from the cathode to organic layer is promoted significantly owing to silver NCs induced lightning rod effect, the Alq(3) OLEDs luminous efficiency is increased up to a factor of 6. In poly(3-hexylthiophene) (P3HT) polymer solar cells, the active layer absorption is enhanced in the presence of silver NCs, which can be ascribed to NCs induced light scattering effect as well as to plasmon enhanced local electric field effect. As a result, photocurrent of the solar cells is increased and the power conversion efficiency (PCE) is improved up to 20%. The comparative study of surface plasmon effects in different organic optoelectronic devices reveals interesting features of the surface plasmon and allows optimization of optoelectronic devices from a novel point of view. (C) 2012 Elsevier B. V. All rights reserved.
Article
Noble metal nanoparticles (NPs) possess size- and shape- dependent optical properties, suggesting the possibility of tuning desired optical properties of ensemble NPs at single NP resolution and underscoring the importance of probing the sizes and shapes of single NPs in situ and in real-time. In this study, we synthesized twelve colloids of Ag NPs. Each colloid contains various sizes and shapes of single NPs, showing rainbow colors with peak-wavelength of absorption spectra from 393 to 738 nm. We correlated the sizes and shapes of single NPs determined by high-resolution transmission electron microscopy (HRTEM) with scattering localized surface plasmon resonance (LSPR) spectra of single NPs characterized by dark-field optical microcopy and spectroscopy (DFOMS). Single spherical (2-39 nm in diameter), rod (2-47 nm in length with aspect ratios of 1.3-1.6), and triangular (4-84 nm in length with thickness of 2-27 nm) NPs show LSPR spectra (λ(max)) at 476±5 or 533±12, 611±23, and 711±40 nm, respectively. Notably, we observed new cookie-shaped NPs, which exhibit LSPR spectra (λ(max)) at 725±10 nm with a shoulder peak at 604±5 nm. Linear correlations of sizes of any given shape of single NPs with their LSPR spectra (λ(max)) enable the creation of nano optical rulers (calibration curves) for identification of the sizes and shapes of single NPs in solution in real time using DFOMS, offering the feasibility of using single NPs as multicolored optical probes for study of dynamics events of interest in solutions and living organisms at nm scale in real time.