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Silver-based nanoantimicrobials: Mechanisms, ecosafety, and future perspectives
Abstract
Silver nanoparticles (AgNPs) are metallic zero-dimensional nanomaterials that have attracted a lot of attention due to their conductivity, chemical resistance, antibacterial, antiviral, antifungal, antiangiogenic, and antiinflammatory properties. Applying Ag as a microbiocidal agent involves oxidation Ag⁰ to the Ag⁺. AgNPs are well-known for their excellent antimicrobial effects against numerous organisms such as bacteria, fungi, and viruses. Direct contact of AgNPs with large surfaces on the cell wall of bacteria can result in damage to the membrane, causing leakage of cell contents and death of cells. When pathogenic cells are exposed to the AgNPs, a significantly large number of ROS was generated. AgNPs can inhibit the production of different kinds of extracellular hydrolytic enzymes as well as germ tube formation of fungi. Also, AgNPs influence the biosynthesis of organic acid in some fungi and alter the profile of extracellular enzyme, although the total enzymatic activity is increased. Furthermore, AgNPs can disturb the integrity of cell wall and cell regulatory mechanisms, leading to pore formation and cell collapse. The antiviral properties of AgNPs have been reported recently. AgNPs are recorded to associate with glycoproteins on the viral surface and have links to the host cells and then introduce their virus behavior through contact with the viral genome.
... Furthermore, nanoparticles demonstrate the ability to inhibit microbial proliferation by diffusing into the exopolysaccharide matrix of biofilms, downregulating quorum sensing proteins and/or enhancing quorum quenching within biofilm architectures, subsequently leading to degradation of extracellular polymeric substances (EPS) and microbial mortality in natural environments. The antimicrobial efficacy of nanoparticles is controlled by various parameters, including particle dimensions, concentration, pH conditions, exposure time, morphology and surface modification (47,48). ...
... The rationale behind the mortality of second stage juveniles as a result of AgNPs exposure can be explained in a way that metallic nanoparticles could be held responsible for inducing oxidative stress within the cells of nematodes (Touseef et al., 2021). The cuticular disruption in the structure of nematode has been reported to be associated with the disruption caused by AgNPs in the normal functioning mechanism of ATP synthesis, membrane permeability and response to oxidative stress (Ghadam et al., 2021). Taha Lim et al. (2012) demonstrated the mechanism of toxicity in nematode, C. elegans by investigating the oxidative stress in reproduction toxicity. ...
The green synthesis of AgNPs from the calli extract of Centella asiatica was confirmed by the detailed analysis of UVÀVis spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR) which revealed the size, shape, chemical composition and functional groups involved in the AgNPs formation. The in-vitro raised cowpea plants were given root dip treatment in Murashige and Skoog (MS) suspension medium supplemented with LC 50-75 mg/mL AgNPs followed by their transfer to glass house conditions for acclimatization. To evaluate the efficiency of root dip treatment, the acclimatized plants were inoculated with 2000 J2s of M. arenaria and the plants were observed on weekly basis. A differential growth response was observed from the cowpea plants under glass house conditions. A treatment plan designed showed that P4 plants showed a significant defense response against the biotic stress of M. arenaria as indicated by the percentage response of several growth parameters such as-plant height of 49.22 § 0.89 %, plant fresh mass of 46.12 § 0.83 %, plant dry mass of 9.3 § 0.17 % and nodule number of 38 § 0.68 % were reported in P4 plants after 6 weeks of J2s inoculation. Confocal microscopy of root sections of P3 cowpea plants revealed the presence of M. arenaria J2s in the corti-cal and provascular regions, however, in case of P4 plants an intact cellular structure was maintained. The application of AgNP didn't show any toxic effect on the growth of plant.
... The produced NPs can strengthen the quorum in the biofilm structure or reduce the expression of operon associated with the quorum sensing proteins. Also, NPs size, pH of environment, NPs concentration, and length of contact time of NPs with microbial cells, shape and coating of NPs can all influence their antimicrobial activity [28,49]. Faizi et al. ...
The biodeterioration of cultural heritage monuments is a worldwide phenomenon, closely linked to the presence of microorganisms and macroorganisms. Microbial colonization leads to physical, chemical damage and esthetic changes. Synthetic polymers, particularly acrylics, are often used to consolidate and protect monuments and artistic stone surfaces. To increase acrylics performances regarding to durability and antimicrobials’ activity, nanoparticles (NPs) were added to polymers. In this study, silver NP was biosynthesized by Malva sylvestris aqueous extract. Furthermore, the in situ method was used for nanocomposite synthesis, which would be simplified the procedure of synthesis. For this, the precursors including the plant aqueous extract, AgNO3 solution and polymer were mixed, and nanocomposite was formed. The morphological characteristics of the obtained nanocomposite were determined using field emission scanning electron microscope (FESEM). The energy-dispersive X-ray (EDX) confirmed AgNPs existence in the composite. Next, the nanocomposite’s antibacterial properties were tested on Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Cladosporium cladosporioides, Aspergillus niger, and Alternaria alternata. The antibacterial activity of bioengineered nanocomposite compared to acrylic polymer, alone. The results of antimicrobial experiments have shown that the number of bacterial and fungal cells was decreased by 1 logarithm in the polymer, and by 2 to 4 logarithms in the nanocomposite that the antimicrobial effect of latter was notably increased. This study was based on applying this nanocomposite to improve conservation strategies for stony cultural heritage. Further experiments should be performed to evaluate the efficacy of this nanocomposite on outdoor stony model.
... For example, it has been shown to have antibacterial, anticancer, antioxidant, and anti-inflammatory properties [25][26][27][28][29]. Another favorable point is that ZnO can be doped (the incorporation of a low concentration of impurities in a semiconductor material) with other materials to enhance its properties [30,31]. Silver is an additional possible dopant for ZnO and an element that has shown antimicrobial, antiseptic, antifungal, and antiviral characteristics [32][33][34]. In this sense, ZnO nanostructures can be doped with elements with strong and proven antimicrobial activity, such as Ag and Cl, to improve its antimicrobial potential [35][36][37]. ...
Citation: Sánchez-Serrano, S.; González-Méndez, D.J.; Olivas-Valdez, J.A.; Millán-Aguiñaga, N.; Evangelista, V.; Contreras, O.E.; Cardoza-Contreras, M.N. pH-Responsive Chitosan-Doped ZnO Hybrid Hydrogels for the Encapsulation of Bioactive Compounds in Aquaculture. Polymers 2023, 15, 4105. https:// Abstract: In this study, we synthesized and characterized pH-responsive Chitosan-AgCl-doped ZnO hybrid hydrogels and evaluated their potential for loading aquaculture bioactive compounds, and assessed their antimicrobial properties against a threatening pathogen associated with disease across a broad spectrum of warm water fish and invertebrates. Hydrogel characterization consisted of assessing morphology via SEM, composition via EDS, hydrogels' network components interactions via FT-IR and pH response through swelling behavior determinations. The swelling characterization of the synthesized hydrogels demonstrated a pH-responsive behavior, showing that low pH values caused the hydrogel polymeric network to expand and capture more of the aqueous solution. These characteristics make the synthesized hydrogels suitable for the encapsulation and controlled release of drugs and bioactive compounds in aquaculture. Chitosan_ZnO hybrid hydrogels showed great antimicrobial activity against Vibrio harveyi, even better than that of loaded PB hydrogels. Here, we provide evidence for the potential capacity of Chitosan_ZnO hybrid hydrogels for the preventive and curative treatment of diseases that impact aquaculture animal health and prevent drug resistance by bacteria.
This study is aimed at the in situ preparation and antibacterial study of silver nanoparticles within the matrix of an eco‐friendly, biocompatible, biodegradable, and bioavailable biopolymer (chitosan) to form Chi–AgNP film via multiple noncovalent interactions between the organic polymer and the nanoparticles. The film is fully characterized by infrared and ultraviolet spectroscopy, scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. The characterization confirms the successful incorporation of silver nanoparticles into the polymeric network. Infrared spectroscopy reveals peaks corresponding to the vibration of functional groups present in chitosan with enhanced intensity and blueshifts caused by the presence of silver nanoparticles. Well‐monodispersed spherical silver nanoparticles with an average size of 10 nm are observed in the Chi–AgNP film. The surface plasmon resonance at 447 nm is consistent with a typical silver plasmon. Furthermore, the antibacterial effects on E. coli and S. aureus were determined and attributed to the release of AgNPs observed by UV absorption.
In this study, the extract of two strains of cyanobacteria was used for the synthesis of silver nanoparticles (NPs). UV-vis spectroscopy, X-ray diffraction, dynamic light scattering and field emission scanning electron microscopy (FESEM) analyses were carried out to characterise the NPs. The antioxidant activity and heavy metal detection properties were investigated; moreover, their minimum inhibitory concentration and minimum bactericidal concentration against the multi-drug resistant bacteria were determined. The most abundant materials in these extracts were carbohydrates, so the biosynthesis of NPs using exopolysaccharide (EPS) was also investigated. The surface plasmon resonance of NPs had a peak at 435 nm and EPS NPs at 350-450 nm. The NPs produced by Nostoc sp. IBRC-M5064 extract revealed the face-centred cubic (fcc) structure of AgCl, while NPs of N. pruniforme showed the fcc crystalline structure of Ag 3 PO 4 and AgCl. The FESEM showed the spherical shape of these NPs. The AgCl/Ag 3 PO 4 colloid, in comparison with AgCl, showed better antioxidant activity and antibacterial effect. The heavy metal detection analysis of NPs revealed that the NPs of both stains involved in Hg (NO 3) 2 detection.
Viral infections have recently emerged not only as a health threat to people but rapidly became the cause of universal fatality on a large scale. Nanomaterials comprising functionalized nanoparticles (NPs) and quantum dots and nanotechnology-associated innovative detection methods, vaccine design, and nanodrug production have shown immense promise for interfacing with pathogenic viruses and restricting their entrance into cells. These viruses have been scrutinized using rapid diagnostic detection and therapeutic interventional options against the caused infections including vaccine development for prevention and control. Coronaviruses, namely SARS-CoV, MERS-CoV, and SARS-CoV-2, have endangered human life, and the COVID-19 (caused by SARS-CoV-2) outbreak has become a perilous challenge to public health globally with huge accompanying morbidity rates. Thus, it is imperative to expedite the drug and vaccine development efforts that would help mitigate this pandemic. In this regard, smart and innovative nano-based technologies and approaches encompassing applications of green nanomedicine, bio-inspired methods, multifunctional bioengineered nanomaterials, and biomimetic drug delivery systems/carriers can help resolve the critical issues regarding detection, prevention, and treatment of viral infections. This perspective review expounds recent nanoscience advancements for the detection and treatment of viral infections with focus on coronaviruses and encompasses nano-based formulations and delivery platforms, nanovaccines, and promising methods for clinical diagnosis, especially regarding SARS-CoV-2.
Aedes mosquitoes are the most important group of vectors that transmit pathogens, including arboviruses, and cause human diseases such as dengue fever, yellow fever, Zika virus, and Chikungunya. Biosynthesis and the use of green silver nanoparticles (AgNPs) is a vital step to identify reliable and eco-friendly controls for these vectors. In this study, Aedes (Ae.) aegypti larvae (2nd and 3rd instar) were exposed to leaf extracts of Ricinus communis (Castor) and AgNPs synthesized from the extract to evaluate their larvicidal potential. Synthesized AgNPs were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (XRD). Ae. aegypti larvae were treated with different concentrations (50–250 ppm) of the leaf extract and synthesized AgNPs. There were five replicates per treatment, in addition to a positive (temephos) and negative control (dechlorinated water). Mortality was recorded after 12, 24, 36, and 48 h and the data were subjected to Probit analysis. The nanoparticles were more toxic (LC50 = 46.22 ppm and LC90 = 85.30 ppm) than the plant extract (106.24 and 175.73 ppm, respectively). The leaf extracts of Ricinus communis were subjected to HPLC analysis to identify their chemical constituents. This study suggests that plant extracts and synthesized nanoparticles are excellent alternatives to hazardous chemical pesticides used to control vector mosquitoes. This is a potentially useful technique that can reduce aquatic toxicity from insecticide use.
Nanoparticles are expected to play a vital role in the management of future plant diseases, and they are expected to provide an environmentally friendly alternative to traditional synthetic fungicides. In the present study, silver nanoparticles (AgNPs) were green synthesized through the mediation by using the endophytic bacterium Pseudomonas poae strain CO, which was isolated from garlic plants (Allium sativum). Following a confirmation analysis that used UV–Vis, we examined the in vitro antifungal activity of the biosynthesized AgNPs with the size of 19.8–44.9 nm, which showed strong inhibition in the mycelium growth, spore germination, the length of the germ tubes, and the mycotoxin production of the wheat Fusarium head blight pathogen Fusarium graminearum. Furthermore, the microscopic examination showed that the morphological of mycelia had deformities and collapsed when treated with AgNPs, causing DNA and proteins to leak outside cells. The biosynthesized AgNPs with strong antifungal activity were further characterized based on analyses of X-ray diffraction, transmission electron microscopy, scanning electron microscopy, EDS profiles, and Fourier transform infrared spectroscopy. Overall, the results from this study clearly indicate that the biosynthesized AgNPs may have a great potential in protecting wheat from fungal infection.
Packaging is an integral part of food products, allowing the preservation of their quality. It plays an important role, protecting the packed product from external conditions, maintaining food quality, and improving properties of the packaged food during storage. Nevertheless, commonly used packaging based on synthetic non-biodegradable polymers causes serious environmental pollution. Consequently, numerous recent studies have focused on the development of biodegradable packaging materials based on biopolymers. In addition, biopolymers may be classified as active packaging materials, since they have the ability to carry different active substances. This review presents the latest updates on the use of silver nanoparticles in packaging materials based on biopolymers. Silver nanoparticles have become an interesting component of biodegradable biopolymers, mainly due to their antimicrobial properties that allow the development of active food packaging materials to prolong the shelf life of food products. Furthermore, incorporation of silver nanoparticles into biopolymers may lead to the development of materials with improved physical-mechanical properties.
According to the Food and Agriculture Organization (FAO), food wastage still causes massive economic loss. A major role in this loss is played by the activities of microbial organisms. Treatments such as heat and irradiation can reduce microorganisms in fruits and vegetables and hence reduce postharvest loss. However, some of these treatments can injure the fruit. Effective chemical treatments against bacterial infestations can result in resistance. A more recent method is the use of silver nanoparticles. These can act in a number of ways including at cellular level by inhibiting the cell wall synthesis, by binding to the surface of the cell membrane and by interposing between the DNA base pairs, and by inhibiting biofilm formation, affecting the thiol group of enzymes, affecting bacterial peptides and hence interfering with cell signaling and attaching to the 30S ribosome subunit. A groundbreaking way to survey the effects of the silver nanoparticles on bacterial populations is by flow cytometry. It allows measurement of many characteristics of single cells, including their functional characteristics such as viability and cell cycle. Bacterial viability assays are used with great efficiency to evaluate antibacterial activity by evaluating the physical rupture of the membrane of the bacteria.
In this review, the presentation of the synthetic routes of plasmonic gold nanoparticles (Au NPs), fluorescent gold nanoclusters (Au NCs), as well as self-assembled Au-containing thiolated coordination polymers (Au CPs) was highlighted. We exclusively emphasize the gold products that are synthesized by the spontaneous interaction of tetrachloroaurate(III) ions (AuCl4¯) with bioligands using amine and thiolate derivatives, including mainly amino acids. The dominant role of the nature of the applied reducing molecules as well as the experimental conditions (concentration of the precursor metal ion, molar ratio of the AuCl4¯ ions and biomolecules; pH, temperature, etc.) of the syntheses on the size and structure-dependent optical properties of these gold nanohybrid materials have been summarized. While using the same reducing and stabilizing biomolecules, the main differences on the preparation conditions of Au NPs, Au NCs, and Au CPs have been interpreted and the reducing capabilities of various amino acids and thiolates have been compared. Moreover, various fabrication routes of thiol-stabilized plasmonic Au NPs, as well as fluorescent Au NCs and self-assembled Au CPs have been presented via the formation of –(Au(I)-SR)n– periodic structures as intermediates.
Background
Viral and microbial infections constitute one of the most important life-threatening problems. The emergence of new viral and bacterial infectious diseases increases the demand for new therapeutic drugs.
Purpose
The objective of this study was to use the aqueous and hexane extracts of Lampranthus coccineus and Malephora lutea F. Aizoaceae for the synthesis of silver nanoparticles, and to investigate its possible antiviral activity. In addition to the investigation of the phytochemical composition of the crude methanolic extracts of the two plants through UPLC-MS metabolomic profiling, and it was followed by molecular docking in order to explore the chemical compounds that might contribute to the antiviral potential.
Methods
The formation of SNPs was further confirmed using a transmission electron microscope (TEM), UV-Visible spectroscopy and Fourier transform infrared spectroscopy. The antiviral activity of the synthesized nanoparticles was evaluated using MTT assay against HSV-1, HAV-10 virus and Coxsackie B4 virus. Metabolomics profiling was performed using UPLC-MS and molecular docking was performed via Autodock4 and visualization was done using the Discovery studio.
Results
The early signs of SNPs synthesis were detected by a color change from yellow to reddish brown color. The TEM analysis of SNPs showed spherical nanoparticles with mean size ranges between 10.12 nm to 27.89 nm, and 8.91 nm 14.48 nm for Lampranthus coccineus and Malephora lutea aqueous and hexane extracts respectively. The UV-Visible spectrophotometric analysis showed an absorption peak at λmax of 417 nm.The green synthesized SNPs of L. coccineus and M. lutea showed remarkable antiviral activity against HSV-1, HAV-10, and CoxB4 virus. Metabolomics profiling of the methanolic extract of L. coccineus and M. lutea resulted in identifying 12 compounds. The docking study predicted the patterns of interactions between the compounds of L. coccineus and M. lutea with herpes simplex thymidine kinase, hepatitis A 3c proteinase, and Coxsackievirus B4 3c protease, which was similar to those of the co-crystal inhibitors and this can provide a supposed explanation for the antiviral activity of the aqueous and nano extracts of L. coccineus and M. lutea.
Conclusion
These results highlight that SNPs of L. coccineus and M. lutea could have antiviral activity against HSV-1, HAV-10, and CoxB4 virus.
Insecticide resistance is the major threat in pest control management. Formulation with silver nanoparticle can be used as an alternative method to overcome these problems. Nanoparticles can provide a cheap and reliable source against Tribolium castaneum. The primary aim of our study is to compare the insecticidal efficacy of nanoparticles with commercial insecticide malathion. Due to the problems associated with the indiscriminate use of synthetic insecticides which promote the insect resistance, it is necessary to give an extra impulse to search alternative ways to control this pest. Silver nanoparticle can provide an accurate solution. In this study, the silver nanoparticles were synthesized, characterized and tested against the Tribolium castaneum. Characterization of the silver nanoparticles was done using ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The study was conducted to compare the mortality rate, ovipositional deterrent, repellent activity and antifeedent activity of different concentration of malathion, silver nanoparticles and the mixed suspension of silver nanoparticles and malathion against Tribolium castaneum. Results of all the assays clearly showed that the combination of silver nanoparticles with malathion shows high insecticidal efficacy. Development of resistance to the pesticide is acknowledged as the most serious problem in pest control. Nanotechnology can revolutionize agriculture and can provide a solution for pest management. The results from the study suggest that the silver nanoparticles have the pesticidal property which is an alternative solution for the insecticide resistance.
Purpose
The pathogenicity in Candida spp was attributed by several virulence factors such as production of tissue damaging extracellular enzymes, germ tube formation, hyphal morphogenesis and establishment of drug resistant biofilm. The objective of present study was to investigate the effects of silver nanoparticles (AgNPs) on growth, cell morphology and key virulence attributes of Candida species.
Methods
AgNPs were synthesized by the using seed extract of Syzygium cumini (Sc), and were characterized by UV-Vis spectrophotometer, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). ScAgNPs were used to evaluate their antifungal and antibacterial activity as well as their potent inhibitory effects on germ tube and biofilm formation and extracellular enzymes viz. phospholipases, proteinases, lipases and hemolysin secreted by Candida spp.
Results
The MICs values of ScAgNPs were ranged from 0.125-0.250 mg/ml, whereas the MBCs and MFCs were 0.250 and 0.500 mg/ml, respectively. ScAgNPs significantly inhibit the production of phospholipases by 82.2, 75.7, 78.7, 62.5, and 65.8%; proteinases by 82.0, 72.0, 77.5, 67.0, and 83.7%; lipase by 69.4, 58.8, 60.0, 42.9, and 65.0%; and hemolysin by 62.8, 69.7, 67.2, 73.1, and 70.2% in C. albicans, C. tropicalis, C. dubliniensis, C. parapsilosis and C. krusei, respectively, at 500 μg/ml. ScAgNPs inhibit germ tube formation in C. albicans up to 97.1% at 0.25 mg/ml. LIVE/DEAD staining results showed that ScAgNPs almost completely inhibit biofilm formation in C. albicans. TEM analysis shows that ScAgNPs not only anchored onto the cell surface but also penetrated and accumulated in the cytoplasm that causes severe damage to the cell wall and cytoplasmic membrane.
Conclusion
To summarize, the biosynthesized ScAgNPs strongly suppressed the multiplication, germ tube and biofilm formation and most importantly secretion of hydrolytic enzymes (viz. phospholipases, proteinases, lipases and hemolysin) by Candia spp. The present research work open several avenues of further study, such as to explore the molecular mechanism of inhibition of germ tubes and biofilm formation and suppression of production of various hydrolytic enzymes by Candida spp.
Silver nanoparticles (AgNPs) are antimicrobial agents that have a wide spectrum of action, including against pathogenic bacteria and spoilage fungi. However, their mechanism of action is not completely clarified. Nowadays, scientific interest on biological synthesis of AgNPs is growing, with emphasis in their extracellular biosynthesis by microbial cells, as it is the most reliable and ecologically correct method for production, yielding no toxic residues. AgNPs may be incorporated to biodegradable and non-biodegradable polymers for the production of food packages with antimicrobial properties, leading to greater safety and longer shelf life. However, it is important to carry out migration tests for new food packages incorporated with AgNPs, based on the effective levels for their inclusion in the packaging materials.
The acronym ESKAPE includes six nosocomial pathogens that exhibit multidrug resistance and virulence: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. Persistent use of antibiotics has provoked the emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) bacteria, which render even the most effective drugs ineffective. Extended spectrum β-lactamase (ESBL) and carbapenemase producing Gram negative bacteria have emerged as an important therapeutic challenge. Development of novel therapeutics to treat drug resistant infections, especially those caused by ESKAPE pathogens is the need of the hour. Alternative therapies such as use of antibiotics in combination or with adjuvants, bacteriophages, antimicrobial peptides, nanoparticles, and photodynamic light therapy are widely reported. Many reviews published till date describe these therapies with respect to the various agents used, their dosage details and mechanism of action against MDR pathogens but very few have focused specifically on ESKAPE. The objective of this review is to describe the alternative therapies reported to treat ESKAPE infections, their advantages and limitations, potential application in vivo, and status in clinical trials. The review further highlights the importance of a combinatorial approach, wherein two or more therapies are used in combination in order to overcome their individual limitations, additional studies on which are warranted, before translating them into clinical practice. These advances could possibly give an alternate solution or extend the lifetime of current antimicrobials.
New strategies are needed to develop new drugs to treat emerging infectious diseases and microbial resistance. A new effective strategy is to design drugs combined with metal nanoparticles to overcome infections of multidrug-resistant microbes. In this study, we investigated the anti-microbial and anticancer properties of three differently shaped silver nanoparticles (S1-S3) against a wide range of microorganisms as well as two types of carcinoma cells. The three forms of silver nanoparticles (Ag-NPs) were investigated against Coxsackievirus B3 and 5 fungal strains (Aspergillus fumigatus, Candida albicans, Geotricum candidum, Aspergillus niger, Trichophyton mentagrophytes) while for antibacterial and anticancer evaluation, S2 was used. Our results demonstrated that all forms had antiviral activities against virus replication with TI ranging from 0.4 to 30 and reduction in virus titers ranged from 0 to 4 log10 TCID50. On the other hand, only Ag-NPs S2 exhibited antifungal activities, mostly against Trichophyton mentagrophytes. Also, Ag-NP S2 showed antibacterial effects against some gram-negative bacteria (Escherichia coli, Acinetobacter baumannii, Klebsiella pneumonia, Salmonella typhi, and Enterobacter cloacae) and some positive bacteria (Bacillus subtilis, Staphylococcus aureus, Streptococcus mutans). Furthermore, Ag-NPs displayed a significant cytotoxic potential in cancerous Hep-G2 and A549 cell lines. The results obtained demonstrate that Ag-NPs can be utilized as strong antimicrobial and anticancer agents.
Silver nanoparticles (AgNPs) can be synthesized from a variety of techniques including physical, chemical and biological routes. They have been widely used as nanomaterials for manufacturing cosmetic and healthcare products, antimicrobial textiles, wound dressings, antitumor drug carriers, etc. due to their excellent antimicrobial properties. Accordingly, AgNPs have gained access into our daily life, and the inevitable human exposure to these nanoparticles has raised concerns about their potential hazards to the environment, health, and safety in recent years. From in vitro cell cultivation tests, AgNPs have been reported to be toxic to several human cell lines including human bronchial epithelial cells, human umbilical vein endothelial cells, red blood cells, human peripheral blood mononuclear cells, immortal human keratinocytes, liver cells, etc. AgNPs induce a dose-, size- and time-dependent cytotoxicity, particularly for those with sizes ≤10 nm. Furthermore, AgNPs can cross the brain blood barrier of mice through the circulation system on the basis of in vivo animal tests. AgNPs tend to accumulate in mice organs such as liver, spleen, kidney and brain following intravenous, intraperitoneal, and intratracheal routes of administration. In this respect, AgNPs are considered a double-edged sword that can eliminate microorganisms but induce cytotoxicity in mammalian cells. This article provides a state-of-the-art review on the synthesis of AgNPs, and their applications in antimicrobial textile fabrics, food packaging films, and wound dressings. Particular attention is paid to the bactericidal activity and cytotoxic effect in mammalian cells.
Objectives The widespread application of nano-enabled products and the increasing likelihood for workplace exposures make understanding engineered nanomaterial (ENM) effects in exposed workers a public and occupational health priority. The aim of this study was to report on the current state of knowledge on possible adverse effects induced by ENM in humans to determine the toxicological profile of each type of ENM and potential biomarkers for early detection of such effects in workers.
Methods A systematic review of human studies and epidemiological investigations of exposed workers relative to the possible adverse effects for the most widely used ENM was performed through searches of major scientific databases including Web of Science, Scopus, and PubMed.
Results Twenty-seven studies were identified. Most of the epidemiological investigations were cross-sectional. The review found limited evidence of adverse effects in workers exposed to the most commonly used ENM. However, some biological alterations are suggestive for possible adverse impacts. The primary targets of some ENM exposures were the respiratory and cardiovascular systems. Changes in biomarker levels compared with controls were also observed; however, limited exposure data and the relatively short period since the first exposure may have influenced the incidence of adverse effects found in epidemiological studies.
Conclusions There is a need for longitudinal epidemiologic investigations with clear exposure characterizations for various ENM to discover potential adverse health effects and identify possible indicators of early biological alterations. In this state of uncertainty, precautionary controls for each ENM are warranted while further study of potential health effects continues.
In table 1, the reference for AgNo3/thermal decomposition was incorrectly stated as [13] when it should be [20]. A corrected version of the table is presented here. (Table presented).
Silver nanoparticles (AgNPs) are considered a promising alternative to the use of antibiotics in fighting multidrug-resistant pathogens. However, their use in medical application is hindered by the public concern regarding the toxicity of metallic nanoparticles. In this study, rationally designed AgNP were produced, in order to balance the antibacterial activity and toxicity. A facile, environmentally friendly synthesis was used for the electrochemical fabrication of AgNPs. Chitosan was employed as the capping agent, both for the stabilization and to improve the biocompatibility. Size, morphology, composition, capping layer, and stability of the synthesized nanoparticles were characterized. The in vitro biocompatibility and antimicrobial activities of AgNPs against common Gram-negative and Gram-positive bacteria were evaluated. The results revealed that chitosan-stabilized AgNPs were nontoxic to normal fibroblasts, even at high concentrations, compared to bare nanoparticles, while significant antibacterial activity was recorded. The silver colloidal dispersion was further mixed with essential oils (EO) to increase the biological activity. Synergistic effects at some AgNP–EO ratios were observed, as demonstrated by the fractionary inhibitory concentration values. Our results reveal that the synergistic action of both polymer-stabilized AgNPs and essential oils could provide a significant efficiency against a large variety of microorganisms, with minimal side effects.
Currently available antiviral drugs have certain limitations. Therefore, silver nanoparticles (Ag-NPs) have recently received an increasing attention with respect to their antibacterial and antiviral properties. This in-vitro study aimed to investigate the inhibition effect of Ag-NPs on viral replication (bovine herpesvirus-1; BoHV-1 as a model) and to determine the therapeutic, safe and cytotoxic concentrations. The cytotoxicity of MDBK cells induced by different Ag-NPs concentrations was investigated by using the methyl thiazolyl tetrazolium (MTT) assay. The infected, treated and cellular MDBK controls were stained with neutral red (NR) stain to monitor the cytopathic effects (CPEs) of BoHV-1 and the protective effects of Ag-NPs that inhibit the viral infections. Ag-NPs were safe for the MDBK cell culture at a concentration of 24 μg/mL medium. The highest concentrations were cellular toxic with different degrees. Also, Ag-NPs could protect the MDBK cell culture from BoHV-1 infection at a safety concentration (24 μg/mL medium) when incubate a mixture of Ag-NPs suspension and BoHV-1 prior infect cells. In conclusion, Ag-NPs can be used in vitro safely at the recommended concentration to protect the cellular culture against viral replications. Ag-NPs at nontoxic concentrations (24 μg/mL) are capable of inhibiting BoHV-1 when they are administered prior to viral infection.
Multidrug-resistant bacteria (MDRB) are extremely dangerous and bring a serious threat to health care systems as they can survive an attack from almost any drug. The bacteria's adaptive way of living with the use of antimicrobials and antibiotics caused them to modify and prevail in hostile conditions by creating resistance to known antibiotics or their combinations. The emergence of nanomaterials as new antimicrobials introduces a new paradigm for antibiotic use in various fields. For example, silver nanoparticles (AgNPs) are the oldest nanomaterial used for bactericide and bacteriostatic purposes. However, for just a few decades these have been produced in a biogenic or bio-based fashion. This review brings the latest reports on biogenic AgNPs in the combat against MDRB. Some antimicrobial mechanisms and possible silver resistance traits acquired by bacteria are also presented. Hopefully, novel AgNPs-containing products might be designed against MDR bacterial infections.
Infectious diseases remain one of the leading causes of morbidity and mortality worldwide. The WHO and CDC have expressed serious concern regarding the continued increase in the development of multidrug resistance among bacteria. Therefore, the antibiotic resistance crisis is one of the most pressing issues in global public health. Associated with the rise in antibiotic resistance is the lack of new antimicrobials. This has triggered initiatives worldwide to develop novel and more effective antimicrobial compounds as well as to develop novel delivery and targeting strategies. Bacteria have developed many ways by which they become resistant to antimicrobials. Among those are enzyme inactivation, decreased cell permeability, target protection, target overproduction, altered target site/enzyme, increased efflux due to over-expression of efflux pumps, among others. Other more complex phenotypes, such as biofilm formation and quorum sensing do not appear as a result of the exposure of bacteria to antibiotics although, it is known that biofilm formation can be induced by antibiotics. These phenotypes are related to tolerance to antibiotics in bacteria. Different strategies, such as the use of nanostructured materials, are being developed to overcome these and other types of resistance. Nanostructured materials can be used to convey antimicrobials, to assist in the delivery of novel drugs or ultimately, possess antimicrobial activity by themselves. Additionally, nanoparticles (e.g., metallic, organic, carbon nanotubes, etc.) may circumvent drug resistance mechanisms in bacteria and, associated with their antimicrobial potential, inhibit biofilm formation or other important processes. Other strategies, including the combined use of plant-based antimicrobials and nanoparticles to overcome toxicity issues, are also being investigated. Coupling nanoparticles and natural-based antimicrobials (or other repurposed compounds) to inhibit the activity of bacterial efflux pumps; formation of biofilms; interference of quorum sensing; and possibly plasmid curing, are just some of the strategies to combat multidrug resistant bacteria. However, the use of nanoparticles still presents a challenge to therapy and much more research is needed in order to overcome this. In this review, we will summarize the current research on nanoparticles and other nanomaterials and how these are or can be applied in the future to fight multidrug resistant bacteria.
Silvernanoparticles(AgNPs)aregainingagreatdealofattentioninbiomedicalapplications due to their unique physicochemical properties. In this study, green synthesis of AgNPs was developed using seaweed polysaccharide fucoidan. The AgNPs were further coated with chitosan to form an electrolyte complex on the surface. The developed chitosan–fucoidan complex-coated AgNPs were characterized using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). FT-IR results suggested strong polyelectrolyte complexation between fucoidan and chitosan. The developed chitosan–fucoidan complex-coated AgNPs significantly inhibited microbial growth. Moreover, the AgNPs showed efficient anticancer activity in human cervical cancer cells (HeLa). This study demonstrated that chitosan–fucoidan complex-coated AgNPs hold high potential for food and cosmeceutical applications.
Zinc oxide is an essential ingredient of many enzymes, sun screens, and ointments for pain and itch relief. Its microcrystals are very efficient light absorbers in the UVA and UVB region of spectra due to wide bandgap. Impact of zinc oxide on biological functions depends on its morphology, particle size, exposure time, concentration, pH, and biocompatibility. They are more effective against microorganisms such as Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Sarcina lutea, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Pseudomonas vulgaris, Candida albicans, and Aspergillus niger. Mechanism of action has been ascribed to the activation of zinc oxide nanoparticles by light, which penetrate the bacterial cell wall via diffusion. It has been confirmed from SEM and TEM images of the bacterial cells that zinc oxide nanoparticles disintegrate the cell membrane and accumulate in the cytoplasm where they interact with biomolecules causing cell apoptosis leading to cell death.
AIM: In this study, we evaluated the effect of silver nanoparticles (AgNPs) on the production of aflatoxin B1 (AFB1) through assessment the transcription activity of aflatoxin biosynthesis pathway genes in Aspergillus flavus ATCC28542.
MATERIAL AND METHODS: The mRNAs were quantitative by Real Time-polymerase chain reaction (qRT-PCR) of A. flavus grown in yeast extract sucrose (YES) medium containing AgNPs. Specific primers that are involved in the AFB1 biosynthesis which highly specific to A. flavus, O-methyltransferase gene (omt-A), were designed and used to detect the fungus activity by quantitative PCR assay. The AFB1 production (from A. flavus growth) which effected by AgNPs were measured in YES medium by high-pressure liquid chromatography (HPLC).
RESULTS: The AFB1 produced by A. flavus have the highest reduction with 1.5 mg -100 ml of AgNPs were added in media those records 88.2%, 67.7% and 83.5% reduction by using AgNP HA1N, AgNP HA2N and AgNP EH, respectively. While on mycelial growth give significantly inhibitory effect. These results have been confirmed by qRT-PCR which showed that culture of A. flavus with the presence of AgNPs reduced the expression levels of omt-A gene.
CONCLUSION: Based on the results of the present study, AgNPs inhibit growth and AFB1 produced by Aspergillus flavus ATCC28542. This was confirmed through RT-PCR approach showing the effect of AgNPs on omt-A gene involved in aflatoxin biosynthesis.
Bovine postpartum diseases remain one of the most significant and highly prevalent illnesses with negative effects on the productivity, survival, and welfare of dairy cows. Antibiotics are generally considered beneficial in the treatment of endometritis; however, frequent usage of each antibiotic drug is reason for the emergence of multidrug resistance (MDR) of the pathogenic microorganisms, representing a major impediment for the successful diagnosis and management of infectious diseases in both humans and animals. We synthesized silver nanoparticles (AgNPs) with an average size of 10 nm using the novel biomolecule apigenin as a reducing and stabilizing agent, and evaluated the efficacy of the AgNPs on the MDR pathogenic bacteria Prevotella melaninogenica and Arcanobacterium pyogenes isolated from uterine secretion samples. AgNPs inhibited cell viability and biofilm formation in a dose-and time-dependent manner. Moreover, the metabolic toxicity of the AgNPs was assessed through various cellular assays. The major toxic effect of cell death was caused by an increase in oxidative stress, as evidenced by the increased generation of reactive oxygen species (ROS), malondialdehyde, protein carbonyl content, and nitric oxide. The formation of ROS is considered to be the primary mechanism of bacterial death. Therefore, the biomolecule-mediated synthesis of AgNPs shows potential as an alternative antimicrobial therapy for bovine metritis and endometritis.
Colloids and especially silver are increasingly used in a variety of worldwide applications because of their potential antimicrobial activity and their plasmotic and conductivity properties. This research reports the fungitoxic properties of colloidal silver on mycelial growth of important plant pathogens: Alternaria brassicicola, Botrytis cinerea, Aspergillus flavus, Aspergillus niger, Fusarium culmorum, Fusarium oxysporum, Penicillium digitatum and Sclerotinia sclerotiorum. Although variable responses towards each compound were observed within the species the results revealed a clear reaction to limiting mycelium growth relative to various concentration of Colloidal silver (CS). Results were expressed as effective concentrations which inhibit mycelial growth by 50% and 90% respectively (EC50 and EC90). Efficiency of colloidal silver on mycelial growth inhibition of different isolates based on EC50 have the following values: 3.69 ppm for Alternaria brassicicola, 7.32 ppm for Botrytis cinerea, 18.21 ppm for Aspergillus flavus, 10.43 ppm for Aspergillus niger, 11.99 ppm for Fusarium culmorum, 12.27 ppm for Fusarium oxysporum, 10.82 ppm for Penicillium digitatum and 6.34 ppm for Sclerotinia. According to the obtained results the antifungal activity of colloidal silver particles as biocide has potential for using it as a non-aggressive treatment in horticulture and sustainable horticulture.
Currently, nanotechnology represents an important tool and an efficient option for extending the shelf life of foods. Reducing particle size to nanometric scale gives materials distinct and improved properties compared to larger systems. For food applications, this technology allows the incorporation of hydrophilic and lipophilic substances with antimicrobial and antioxidant properties that can be released during storage periods to increase the shelf life of diverse products, including whole and fresh-cut fruits and vegetables, nuts, seeds, and cheese, among others. Edible coatings are usually prepared with natural polymers that are non-toxic, economical, and readily available. Nanosystems, in contrast, may also be prepared with biodegradable synthetic polymers, and liquid and solid lipids at room temperature. In this review, recent developments in the use of such nanosystems as nanoparticles, nanotubes, nanocomposites, and nanoemulsions, are discussed critically. The use of polymers as the support matrix for nanodispersions to form edible coatings for food preservation is also analyzed, but the central purpose of the article is to describe available information on nanosystems and their use in different food substrates to help formulators in their work.
Root-knot nematode, Meloidogyne incognita is the most economically important plant parasitic nematode species that cause serious damage to most agricultural crops including tomato worldwide. Nematicides do not provide long-term suppression of root-knot nematodes, and environmental and human health concerns are resulting in increased restrictions on their use. A greenhouse experiment was conducted to evaluate the effect of silver nanoparticles (AgNPs) at concentrations of 0.25, 0.5 and 1 mM as a potential nematicide on M. incognita infecting tomato. AgNP was biologically and chemically synthesized by a reaction of silver nitrate with ginger (Zingiber officinale) rhizomes aqueous extract and sodium borohydride, respectively. Results indicated that application of AgNPs improved plant growth and reduced nematode infection in comparison to silver nitrate and control treatments. The highest increment of fresh weight as well as the lowest numbers of galls and egg-masses was obtained when tomato plants was treated with AgNP produced by ginger extract at 1 mM.
We report synthesis of silver nanoparticles (AgNPs) from Streptomyces xinghaiensis OF1 strain, which were characterised by UV–Vis and Fourier transform infrared spectroscopy, Zeta sizer, Nano tracking analyser, and Transmission electron microscopy. The antimicrobial activity of AgNPs alone, and in combination with antibiotics was evaluated against bacteria, namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, and yeasts viz., Candida albicans and Malassezia furfur by using micro-dilution method. The minimum inhibitory concentration (MIC) and minimum biocidal concentration of AgNPs against bacterial and yeast strains were determined. Synergistic effect of AgNPs in combination with antibacterial and antifungal antibiotics was determined by FIC index. In addition, MTT assay was performed to study cytotoxicity of AgNPs alone and in combination with antibiotics against mouse fibroblasts and HeLa cell line. Biogenic AgNPs were stable, spherical, small, polydispersed and capped with organic compounds. The variable antimicrobial activity of AgNPs was observed against tested bacteria and yeasts. The lowest MIC (16 µg ml−1) of AgNPs was found against P. aeruginosa, followed by C. albicans and M. furfur (both 32 µg ml−1), B. subtilis and E. coli (both 64 µg ml−1), and then S. aureus and Klebsiella pneumoniae (256 µg ml−1). The high synergistic effect of antibiotics in combination with AgNPs against tested strains was found. The in vitro cytotoxicity of AgNPs against mouse fibroblasts and cancer HeLa cell lines revealed a dose dependent potential. The IC50 value of AgNPs was found in concentrations of 4 and 3.8 µg ml−1, respectively. Combination of AgNPs and antibiotics significantly decreased concentrations of both antimicrobials used and retained their high antibacterial and antifungal activity. The synthesis of AgNPs using S. xinghaiensis OF1 strain is an eco-friendly, cheap and nontoxic method. The antimicrobial activity of AgNPs could result from their small size. Remarkable synergistic effect of antibiotics and AgNPs offer their valuable potential in nanomedicine for clinical application as a combined therapy in the future.
Nanoparticles, ranging in the size from 1 to 100 nm possess novel or enhanced properties compared with larger particles of bulk materials, based on their specific characteristics such as size, distribution and morphology. Noble metal nanoparticles are widely used in the nano-medicinal application; especially silver nanoparticles, which exhibit antifungal, antibacterial, anti-plasmodial and anti-mosquito properties due to the unique properties such as chemical stability, good conductivity and catalytic activity. Nanoparticles are largely synthesized by a variety of chemical and physical approaches. These techniques being expensive and potentially hazardous to the environment, can pose various biological risks. This has necessitated for the alternate eco-friendly and innocuous approaches. In recent years, the convergence between the two fields; nanotechnology and biology; has evolved a new field of nanobiotechnology that encompasses a number of biochemical and biophysical processes employing biological entities such as algae, bacteria, fungi, viruses, yeasts, and plants. Focus on green synthesis of nanoparticles without employing toxic and expensive chemicals frequently used in conventional chemical and physical processes, has augmented their applications and safe usage. This chapter describes the different methods to synthesize silver nanoparticles with a major focus on synthesizing nanoparticles via green route i.e., by utilizing biological entities for the facile, eco-friendly and cost-effective synthesis.
In this study the production of high surface area silver nanoparticles (AgNPs) are reported from the Dodonaea viscosa plant species under controlled condition. The reaction was completed at 40 °C within 5 h and the product was characterized by several advanced techniques such as PXRD, FTIR, TGA, FESEM, XPS, DRS, BET, and UV-Vis. The prepared AgNPs were also evaluated for antimicrobial activities against pathogenic bacteria and fungi such as multi-drug resistant Staphylococcus aureus (MRSA) and Candida albican at a minimum inhibitory concentration (1 μg/mL) with 9 mL of liquid medium (Nutrient Broth). AgNPs were also found to speed up the reduction of organic pollutants such as 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and azo dyes included Methyl orange (MO), Congo red (CR) and Rhodamine B (RB) which causes pollution. The highest surface area is found for Ag-25 (7.38 m 2 /g) as compared to others NPs might be the highest catalytic potential of Ag-25.
The biosynthesis of nanoparticles (NPs) has recently attracted a lot of research attention due to its being an eco-friendly and economical method. NPs are formed under normal temperatures and pressures. The shape and size of NPs can be controlled by choosing a suitable pH and temperature. In this study, 24 strains of fungi isolated from desert soils were screened for AgNP synthesis. The MS17 isolated was chosen as the superior strain capable of rapidly synthesizing monodisperse AgNPs. The optimum conditions for AgNP synthesis were investigated. AgNPs were characterized by UV–visible spectrophotometry, dynamic light scattering, X-ray diffraction, transmission electron microscopy and Fourier-transform infrared. The NPs produced were found to be in the form of Ag/AgCl with a size range of 5–15 nm. Then, the NPs were capped by proteins and carbohydrates, which play an important role in NP stability. The NPs were capable of antimicrobial activities against the standard bacterial pathogens, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 1431 and the multidrug-resistant P. aeruginosa B52 and P. aeruginosa 48.
Background
Although silver nanoparticles (SNP) have proven antimicrobial activity against different types of microorganisms, the effect of SNP incorporation into acrylic resin to control Candida albicans biofilm formation aiming at the prevention of Candida-associated denture stomatitis has not yet been fully elucidated.
Objectives
This study aimed to evaluate the antimicrobial effect of an acrylic resin containing SNP on C. albicans biofilm growth, the flexural strength of this material and tissue reaction in the subcutaneous connective tissue of rats to SNP.
Method
SNP were synthesized through silver nitrate reduction by sodium citrate. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to verify the size and colloidal stability. SNP were added to acrylic resin monomer (Lucitone 550) at 0.05, 0.5 and 5 vol%. The antimicrobial effect against C. albicans (ATCC 10231) was investigated by the enumeration of colony-forming units (CFUs) and SEM. The three-point bending test was performed to analyze the flexural strength. Tissue reaction was evaluated after 7 and 60 days of implantation in the connective tissue of Wistar rats.
Results
Spherical particles of 5 and 10 nm were obtained. SNP at 0.05 and 0.5% incorporated into acrylic resin was effective in reducing C. albicans biofilm growth (p<.001). SEM revealed that the material was able to disrupt C. albicans biofilm formation and did not reduce the flexural strength compared to control (p>.05). The inflammatory response observed 60 days after implantation SNP in the subcutaneous tissue was similar to control.
Conclusion
It was concluded that SNP addition at 0.05 and 0.5% into acrylic resin exhibited antimicrobial effects against C. albicans biofilm, did not interfere in the flexural strength and may be considered biocompatible.
The materials used in food packaging based on non-biodegradable synthetic polymers pose a serious threat of pollution to the environment. Hence, research is now focused on developing eco-friendly and biodegradable packaging obtained from natural polymers. Pullulan is a microbial exopolysaccharide, obtained on a commercial scale by the yeast-like fungus Aureobasidium pullulans . It is a water-soluble, non-toxic and non-mutagenic edible biopolymer with excellent film-forming abilities and adhesive properties. Furthermore, pullulan presents great potential to fabricate thin, transparent, odorless and tasteless edible films and coating used as packaging material. This review article presents an overview on the basic mechanical and barrier properties of a pullulan-based film. It also describes the modification methods applied in order to obtain multifunctional materials in terms of satisfactory physico-mechanical performance and antimicrobial activity for food packaging.
There are alarming reports of the presence of mycotoxins and the induction of mycotoxicoses in the vital organs of humans and animals, as well as economic loss due to reduced crop yields. In light of these problems, mycotoxin detoxification has become mandatory for the production of healthy products. As the potential for prevention can be absent or limited in the field or during long storage periods, other methods based on several protocols have shown potential usefulness for efficient mycotoxin control; however, few are accepted for practical use. Detoxification can be performed by lactic acid bacteria, Bacillus, moulds, actinobacteria, edible fungi and medicinal plants. Another lower-cost method based on nanoparticles has recently been discovered, and its profitability and efficiency have been proven.
Keywords: Mycotoxins, detoxification, nanoparticles, nanocontrol method
The negative consequences of biofilms are widely reported. A defining feature of biofilms is the extracellular matrix, a complex mixture of biomacromolecules, termed EPS, which contributes to reduced antimicrobial susceptibility. EPS targeting is a promising, but underexploited, approach to biofilm control allowing disruption of the matrix and thereby increasing the susceptibility to antimicrobials. Nanoparticles (NPs) can play a very important role as 'carriers' of EPS matrix disruptors, and several approaches have recently been proposed. In this review, we discuss the application of nanoparticles as antibiofilm technologies with a special emphasis on the role of the EPS matrix in the physicochemical regulation of the nanoparticle–biofilm interaction. We highlight the use of nanoparticles as a platform for a new generation of antibiofilm approaches.
Cereal grains are essential ingredient in food, feed and industrial processing. One of the major causes of cereal spoilage and mycotoxin contamination is the presence of toxigenic Fusarium spp. Nanoparticles have immense applications in agriculture, nutrition, medicine or health but their possible impact on the management of toxigenic fungi and mycotoxins have been very little explored. In this report, the potential of silver nanoparticles (AgNPs) (size 14-100 nm) against the major toxigenic Fusarium spp. affecting crops and their effect on mycotoxin accumulation is evaluated for the first time. The studied Fusarium spp. (and associated mycotoxins) were F. graminearum and F. culmorum (deoxynivalenol, 3-acetyldeoxynivalenol and zearalenone), F. sporotrichioides and F. langsethiae (T-2 and HT-2 toxins), F. poae (nivalenol), F. verticillioides and F. proliferatum (fumonisins B1 and B2) and F. oxysporum (mycotoxins no detected). The factors fungal species, AgNP dose (range 2-45 μg/mL), exposure time (range 2-30 h) and their interactions significantly influence spore viability, lag period and growth rate (GR) in subsequent cultures in maize-based medium (MBM) of all the studied species. The effective lethal doses (ED50, ED90 and ED100) to control spore viability and GR were in the range 1->45 μg/mL depending on the remaining factors. At high exposure times (20-30 h), the three effective doses ranged 1-30 μg/mL for all the studied species. At the end of the incubation period (10 days) mycotoxin levels in MBM cultures inoculated with fungal spores from treatments were strongly related with the size reached by the colony at that time. None of the treatments produced stimulation in conidia germination, GR or mycotoxin biosynthesis with respect to controls. Thus, the antifungal effect of the assayed AgNPs against the tested Fusarium spp. suggests that AgNPs could be a new antifungal ingredient in bioactive polymers (paints, films or coating) likely to be implemented in the agro-food sector for controlling these important toxigenic Fusarium spp. and their main associated mycotoxins.
Most of current influenza virus vaccines fail to develop a strong immunity at lung mucosae (site of viral entry) due to sub-optimal vaccination protocols (e.g. inactivated virus administered by parenteral injections). Mucosal immunity could be improved by using locally-delivered vaccines containing appropriate adjuvants. Here we show, in a mouse model, that inclusion of silver nanoparticles (AgNPs) in virus-inactivated flu vaccine resulted in reduction of viral loads and prevention of excessive lung inflammation following influenza infection. Concomitantly, AgNPs enhanced specific IgA secreting plasma cells and antibodies titers, a hallmark of successful mucosal immunity. Moreover, vaccination in the presence of AgNPs but not with gold nanoparticles, protected mice from lethal flu. Compared with other commercial adjuvants (squalene/oil-based emulsion) or silver salts, AgNPs stimulated stronger antigen specific IgA production with lower toxicity by promoting bronchus-associated lymphoid tissue (BALT) neogenesis, and acted as a bona fide mucosal adjuvant.
Particles with the size of 1-100 nm are known as nanoparticles (NPs). The widespread use of silver NPs (AgNPs) makes it familiar in different industries. They have unique properties as a result of their high surface to volume ratio, although aggregation of NPs interferes with their functions. This phenomenon has several side effects on the environment, the amount of which may depend on the stability of AgNPs. Stability of colloids depends on various agents, such as capping agents and environmental conditions, including pH and ionic strength. In this study, the effects of a variety of electrolytes, such as NaCl (10mM), NaNO 3 (10 and 100mM), and Ca (NO 3) 2 (10mM) at different values of pH were investigated on the aggregation of AgNPs synthesized using an aqueous extract of dried Juglans regia green husk. In NaNO 3 10mM pH 9, NPs were more stable than in other media. Therefore, the special optical and electronic properties of AgNPs in such a medium as well as in water were investigated. The UV-visible extinction spectra of AgNPs in both water and NaNO 3 (10 mM, pH 9.0) showed a surface plasmon resonance (SPR) at 445 nm as well as a broad peak at shorter wavelengths (255 nm). The fluorescence emission spectra of AgNPs at different excitation wavelengths in the range of 245-290 nm revealed emission peaks that were red-shifted in the range of 487-580 nm by the increase in the excitation wavelength. This behavior is attributed to the existence of a variety of emission centers with different energy levels.
The potential use of nanotechnology in the control of toxigenic fungi and mycotoxin production has been little explored. In this report, engineered silver nanoparticles (AgNPs) were synthesized and characterized by single particle Inductively Coupled Plasma Mass Spectrometry. Then, their effectiveness in the control of the growth of the main aflatoxigenic and ochratoxigenic species affecting foods and aflatoxins (AFs) and ochratoxin A (OTA) production was studied. The target species and their associated mycotoxins were Aspergillus flavus (AFB 1 and AFB 2 ), A. parasiticus (AFB 1 , AFB 2 , AFG 1 and AFG 2 ), A. carbonarius, A. niger, A. ochraceus, A. steynii, A. westerdijkiae and Penicillium verrucosum (OTA). Spore suspensions supplemented with AgNPs (average diameter size 30 nm, range 14–100 nm) at doses 0–45 μg/mL were incubated for 2–30 h. At selected exposure times aliquots were removed and cultured on maize-based medium (MBM) for 10 days. In these cultures, percentage of viable spores, effective doses (EDs) to inhibit the number of viable spores to 50%, 90% and 100%, colony lag phases, colony growth rates (GR), EDs to inhibit the colony GR to 50%, 90% and 100% were estimated. AF and OTA levels were determined by UPLC-MS/MS. Under the assayed conditions, effective doses of the AgNPs against all the studied fungal species could be estimated. These doses generally decreased with increasing exposure time and were higher for A. flavus and A. parasiticus than for ochratoxigenic species. Colonies from spores treated at high exposure times (20–30 h) and variable AgNP doses showed long lag phases or even did not occur depending on the fungal species. Colony GR, as well as AF and OTA levels in MBM cultures decreased when AgNP dose and contact period increased. The factors species, AgNP dose, exposure time and their interactions significantly affect fungal growth and AF and OTA accumulation in MBM. The results suggest that AgNPs only or as active ingredient hosted in paints, films or other polymers could be a good strategy in the management of the main aflatoxigenic and ocratoxigenic species affecting food and AF and OTA contamination.
The cell-free culture filtrate (CFF) of the fungi Fusarium chlamydosporum NG30 and Penicillium chrysogenum NG85 was tested to synthesize silver nanoparticles (AgNPs). The synthesized AgNPs were further characterized by means of transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier transform infra-red (FTIR) spectroscopy. TEM revealed their spherical shape, homogeneity and a size range between 6 and 26 nm for F. chlamydosporum AgNPs (FAgNPs) and from 9 to 17.5 nm for P. chrysogenum AgNPs (PAgNPs). DLS showed that the diameter of FAgNPs was narrower than that of PAgNPs. FTIR spectroscopy indicated that the functional groups present in the CFF might be responsible for the reduction of silver ions to form stabilized protein-capped AgNPs. In addition, the AgNPs showed notable antifungal activity and potency in thwarting mycotoxin production. Thus, using Aspergillus flavus as a test microorganism the minimum inhibitory concentration (MIC) was 48, 45 and 50 μg/mL for FAgNPs, PAgNPs and the antifungal compound itraconazole, respectively. Also, when testing Aspergillus ochraceus FAgNPs, PAgNPs and itraconazole led to MIC values of 51, 47 and 49 μg/mL, respectively. The statistical MIC values to inhibit completely the total aflatoxin production by A. flavus were 5.9 and 5.6 μg/mL for FAgNPs and PAgNPs, respectively, and to inhibit the ochratoxin A production by A. ochraceus 6.3 and 6.1 μg/mL for FAgNPs and PAgNPs, respectively. The cytotoxicity assay of the AgNPs on human normal melanocytes (HFB 4) revealed a cell survival of 80% and 75% at a concentration of 6 μg/mL for FAgNPs and PAgNPs, respectively.
The nonradiative conversion of light energy into heat (photothermal therapy, PTT) or sound energy (photoacoustic imaging, PAI) has been intensively investigated for the treatment and diagnosis of cancer, respectively. By taking advantage of nanocarriers, both imaging and therapeutic functions together with enhanced tumour accumulation have been thoroughly studied to improve the pre-clinical efficiency of PAI and PTT. In this review, we first summarize the development of inorganic and organic nano photothermal transduction agents (PTAs) and strategies for improving the PTT outcomes, including applying appropriate laser dosage, guiding the treatment via imaging techniques, developing PTAs with absorption in the second NIR window, increasing photothermal conversion efficiency (PCE), and also increasing the accumulation of PTAs in tumours. Second, we introduce the advantages of combining PTT with other therapies in cancer treatment. Third, the emerging applications of PAI in cancer-related research are exemplified. Finally, the perspectives and challenges of PTT and PAI for combating cancer, especially regarding their clinical translation, are discussed. We believe that PTT and PAI having noteworthy features would become promising next-generation non-invasive cancer theranostic techniques and improve our ability to combat cancers.
In the present study, microalgae Chlorococcum humicola and Chlorella vulgaris were grown in different concentrations of NaCl (25-1000 mM) to elucidate its impact on morphology, lipid synthesis, minerals status and antioxidative responses. Scanning Electron microscopy showed distorted cell morphology and increased cell size by 33.52% (C. humicola) and 27.79% (C. vulgaris) at 100 mM NaCl. Energy Dispersive Spectroscopy data revealed reduction in mineral contents (C, S, Fe, Mg, Si, Mn and Zn) by 14-54% in both algae. Further, C. humicola was found to have high lipid content than C. vulgaris under NaCl regime. The activities of superoxide dismutase, catalase and glutathione reductase were increased by 2.5-5 folds in both algae as compared to control. The increased level of ascorbate, cysteine and proline in both algae indicated tolerance against salinity. Thus, C. humicola and C. vulgaris may exhibit dual benefits viz., high lipid production and reclamation of sodic soil.
Silver nanoparticles (AgNPs) have attracted the attention of researchers due to their properties. Biological synthesis of AgNPs is eco-friendly and cost-effective preferred to physical and chemical methods, which utilize environmentally harmful agents and large amounts of energy. Microorganisms have been explored as potential biofactories to synthesize AgNPs. Bacterial NP synthesis is affected by Ag salt concentration, pH, temperature and bacterial species. In this study, Bacillus spp., isolated from soil, were screened for AgNP synthesis at pH 12 with 5 mM Ag nitrate (AgNO3) final concentration at room temperature. The isolate with fastest color change and the best ultraviolet-visible spectrum in width and height were chosen as premier one. AgNO3 and citrate salts were compared in terms of their influence on NP synthesis. Spherical Ag chloride (AgCl) NPs with a size range of 35-40 nm were synthesized in 1.5 mM Ag citrate solution. Fourier transform infrared analysis demonstrated that protein and carbohydrates were capping agents for NPs. In this study, antimicrobial and antitumor properties of the AgNP were investigated. The resulting AgCl NPs had bacteriostatic activity against four standard spp. And multi-drug resistant strain of Pseudomonas aeruginosa. These NPs are also cytotoxic to cancer cell lines MCF-7, U87MG and T293.
Background:
CD19-specific chimeric antigen receptor (CAR) T cells induce high rates of initial response among patients with relapsed B-cell acute lymphoblastic leukemia (ALL) and long-term remissions in a subgroup of patients.
Methods:
We conducted a phase 1 trial involving adults with relapsed B-cell ALL who received an infusion of autologous T cells expressing the 19-28z CAR at the Memorial Sloan Kettering Cancer Center (MSKCC). Safety and long-term outcomes were assessed, as were their associations with demographic, clinical, and disease characteristics.
Results:
A total of 53 adults received 19-28z CAR T cells that were manufactured at MSKCC. After infusion, severe cytokine release syndrome occurred in 14 of 53 patients (26%; 95% confidence interval [CI], 15 to 40); 1 patient died. Complete remission was observed in 83% of the patients. At a median follow-up of 29 months (range, 1 to 65), the median event-free survival was 6.1 months (95% CI, 5.0 to 11.5), and the median overall survival was 12.9 months (95% CI, 8.7 to 23.4). Patients with a low disease burden (<5% bone marrow blasts) before treatment had markedly enhanced remission duration and survival, with a median event-free survival of 10.6 months (95% CI, 5.9 to not reached) and a median overall survival of 20.1 months (95% CI, 8.7 to not reached). Patients with a higher burden of disease (≥5% bone marrow blasts or extramedullary disease) had a greater incidence of the cytokine release syndrome and neurotoxic events and shorter long-term survival than did patients with a low disease burden.
Conclusions:
In the entire cohort, the median overall survival was 12.9 months. Among patients with a low disease burden, the median overall survival was 20.1 months and was accompanied by a markedly lower incidence of the cytokine release syndrome and neurotoxic events after 19-28z CAR T-cell infusion than was observed among patients with a higher disease burden. (Funded by the Commonwealth Foundation for Cancer Research and others; ClinicalTrials.gov number, NCT01044069 .).