Graphene Oxide-silver Nanoparticle Research Articles

Rocephin-graphene oxide-silver nanocomposites: A versatile platform for biomedical applications.

For many years, the synthesis of graphene oxide (GO) had involved exfoliating graphite flakes, and the methods applied were expensive and time-consuming. Thus, an attempt had been made to create an inventive, less expensive method for the synthesis of GO using unrefined, raw carbon-containing material. Modified Hummer's method was used to prepare GO from banana peel. In addition, the metallic silver nanocomposite was also synthesized along with laoding of drug Rocephin where they interact with each other through electrostatic hydrogen bond interaction. The degree of crystallinity and the crystallite size were through x-ray diffraction (XRD) analysis and the crystallite size of AgNPs was found to be 40.40 nm. The scanning electron microscopy (SEM) analysis shows that the morphology of the GO gradually changes with the addition of AgNPs and Rocephin. A blue shift was seen in the absorbance maxima of the raw carbon upon the conjugation of Rocephin in UV analysis. The Fourier-transform infrared spectroscopy, and energy dispersive X-ray (EDX) spectroscopy were used to determine the chemical composition of the samples. Furthermore, a broad biological screening of the synthesized samples had been carried out following the total reducing power (TRP), total antioxidant capacity (TAC), antibacterial, antifungal, MTT (Cytotoxicity of biologically synthesized silver nanoparticles in MDA-MB-231 human breast cancer cells) cell viability, brine shrimp lethality, and hemolytic protocols. Significant results were obtained, and the Rocephin-GO-AgNPs had depicted promising activity as compared with their counterparts. RESEARCH HIGHLIGHTS: The GO was prepared from the raw carbon extracted from banana peels and was used as a substrate for the synthesis Graphene oxide silver nanoparticles (GO-AgNPs) and Rocephin-loaded graphene oxide silver nanoparticles (Rocephin-GO-AgNPs) The structural and compositional analysis of the nanomaterial was carried out, and they were screened for several biomedical applications. The Rocephin-GO-AgNPs exhibit the highest activity as compared with their counterparts.

Engineering Bacterial Biofilm Development and Structure via Regulation of Silver Nanoparticle Density in Graphene Oxide Composite Coating.

Graphene-based composites have shown significant potential in the treatment of biofilm infections in clinical settings due to their exceptional antimicrobial properties and specific mechanisms. Nevertheless, a comprehensive understanding of the influence exerted by nanoparticles embedded in the composites on the development and structure of biofilms is still lacking. Here, we fabricate different graphene oxide-silver nanoparticle (GAg) composite-modified substrates (GAgS) with varying densities of silver nanoparticles (AgNPs) and investigate their effects on planktonic bacterial adhesion, subsequent biofilm formation, and mature biofilm structure. Our findings indicate that the initial attachment of Pseudomonas aeruginosa cells during biofilm formation is determined by the density of AgNPs on the GAgS surface. In contrast, the subsequent transition from adherent bacteria to the biofilm is determined by GAgS's synergistic antimicrobial effect. There exists a threshold for the inhibitory performance of GAgS, where the 20 μg/cm2 GAg composite completely prevents biofilm formation; below this concentration, GAgS delays the development of the biofilm and causes structural changes in the mature biofilm with enhanced bacterial growth and increased production of extracellular polymeric substance. More importantly, GAgS have minimal impact on mammalian cell morphology and proliferation while not inducing hemolysis in red blood cells. These results suggest that GAg composites hold promise as a therapeutic approach for addressing medical devices and implant-associated biofilm infections.

Comparing the antimicrobial properties of graphene oxide silver nanoparticles as a root canal irrigant: A randomized controlled trial

Aim: The current study aimed to compare and evaluate the antimicrobial efficacy of graphene oxide (GO) silver nanoparticle (AgNp) as root canal irrigant (RCI) with other RCIs in maxillary anterior teeth with necrotic pulp. Methods: The GO AgNp RCI was synthesized following modified Turkevich method and subsequent physicochemical characterization was carried out. Sample size was calculated to be 44 and divided into four groups. Following initiation of root canal treatment, preirrigation aerobic and anaerobic samples were collected in suitable medium and the same was done after completion of irrigation adapting the proposed protocol. Further, culture of aerobic and anaerobic samples was done accompanied by determination of bacterial viability count. From the obtained results, statistical analysis was performed and analysis of variance with post hoc was used to compare the antibacterial efficacy between the four irrigants. Results: The statistical analysis ended up with a significant difference in antibacterial properties between GO AgNps and normal saline, 2% chlorhexidine (P < 0.01) against both aerobic and anaerobic organisms. 2.5% sodium hypochlorite and GO AgNp irrigant showed a similar result against aerobic organisms (P = 1.00) while 2.5% sodium hypochlorite was slightly effective against anaerobic organisms (P = 0.83). The bacterial viability counts also showed results in accordance with culture results. Conclusion: From the above results, it can be concluded that the GO AgNp irrigant is an effective biocompatible antimicrobial agent, comparable to that of 2.5% sodium hypochlorite and superior to 2% chlorhexidine and normal saline.

The cytocompatibility of graphene oxide as a platform to enhance the effectiveness and safety of silver nanoparticles through in vitro studies.

The increasing emergence of antibiotic-resistant bacteria and the need to reduce the use of antibiotics call for the development of safe alternatives, such as silver nanoparticles. However, their potential cytotoxic effect needs to be addressed. Graphene oxide provides a large platform that can increase the effectiveness and safety of silver nanoparticles. Graphene oxide and silver nanoparticles complex applied as a part of an innovative material might have direct contact with human tissues, such as skin, or might be inhaled from aerosol or exfoliated pieces of the complex. Thereby, the safety of the prepared complex has to be evaluated carefully, employing a range of methods. We demonstrated the high cytocompatibility of graphene oxide and the graphene oxide-silver nanoparticles complex toward human cell lines, fetal foreskin fibroblasts (HFFF2), and lung epithelial cells (A549). The supporting platform of graphene oxide also neutralized the slight toxicity of bare silver nanoparticles. Finally, in studies on Staphylococcus aureus and Pseudomonas aeruginosa, the number of bacteria reduction was observed after incubation with silver nanoparticles and the graphene oxide-silver nanoparticles complex. Our findings confirm the possibility of employing a graphene oxide-silver nanoparticles complex as a safe agent with reduced silver nanoparticles' cytotoxicity and antibacterial properties.

Ternary Nanocomposite of Activated Charcoal/Reduced Graphene Oxide-Silver Nanoparticles [ACH/Ag@rGO] as a Novel Platform for the First Sensitive Prucalopride Drug Detection in Generic and Innovator Tablets and Human Plasma

Ag@rGO nanocomposite was prepared using an in situ reduction approach of silver ions and the as-synthesized graphite oxide (GO). TEM analysis reveals the crumpled and folded layered structure of rGO with homogeneous dispersed spherical Ag NPs on these rGO nanosheets. The intensity ratio of the D to G bands (ID/IG) in Raman spectra for Ag@rGO indicates a large defect due to Ag NPs intercalation and deposition on rGO surface. XRD pattern indicates the face centered cubic crystal structure of Ag with average crystalline size of 19.63 nm. An electrochemical sensor based on Ag@rGO is first designed for Prucalopride drug oxidation and characterized applying EIS and cyclic voltammetry. Its electrocatalytic effect was enhanced upon utilizing a characterized activated charcoal (ACH) as an electro-modified carbon nanomaterial for CPE. The ternary nanocomposite [ACH/Ag@rGO] as a platform of CPE supposed three times higher response to Prucalopride compared to CPE. Prucalopride was quantified over wide linear ranges of (5.0 × 10−9– 1 × 10−6 M) and (2.0 × 10−8– 1.4 × 10−6 M), with LOD values of 7.95 × 10−10 M and 8.51 × 10−9 M in bulk form and spiked human plasma, respectively. This sensor can thus be adopted easily for the quality control analysis of Prucalopride in formulation and human plasma and for pharmacokinetic study.

Investigation of the formation mechanism of AgNPs-GO in AgNPs-GO liquid band-aids using molecular dynamics simulations, and the effect of GO oxidation on solubility and silver loading

Background and purposeLiquid bandages belong to a new type of wound dressing. Compared to traditional band-aids, liquid bandages are generally suitable for superficial wounds. They are convenient to use, quickly seal wounds, can be applied to special areas, provide a transparent and aesthetically pleasing film after application, and have other functions such as waterproofing. However, there has been limited research on the application of carbon-based materials in antibacterial dressings. MethodsIn this study, the formation mechanism of silver nanoparticle-graphene oxide composites was investigated using computer molecular simulation methods. The influence of graphene oxide oxidation degree on solubility and silver loading was studied. ResultsThrough radial distribution function analysis, it was shown that the solubility of graphene oxide gradually increased and stabilized at 32.5%. Due to steric hindrance and solvent effects, the silver loading continuously decreased and stabilized at 22.5%. These results provide simulated references for further prescription optimization and production process optimization. ConclusionThe simulation results indicate that silver nanoparticles gradually approach, adsorb, and aggregate on the surface of graphene oxide in the solution system. With an increase in the oxidation degree, the solubility of graphene oxide continuously increases, while the silver loading continuously decreases and stabilizes.

GO-Ag-NPs as a promising agent for biomedical, catalytic, electrochemical detection and water treatment technologies; a comprehensive review

Abstract This comprehensive review article discusses the potential applications of graphene oxide-silver nanoparticles (GO-Ag NPs) in various fields, including biomedical, catalytic, electrochemical detection, and wastewater treatment technologies. GO-Ag NPs have gained significant attention due to their unique properties, such as excellent electrical, mechanical, and thermal conductivity, as well as their protective capabilities. The review summarizes the different starting materials and reducing agents that have been used to produce GO-Ag NPs with particle sizes ranging from 2 to 90 nm. Furthermore, the article highlights the various applications of GO-Ag NPs, such as their use in drug delivery, bioimaging, and cancer therapy. Additionally, the review discusses the potential of GO-Ag NPs in catalysis, electrochemical detection, and wastewater treatment. Overall, this review provides a comprehensive overview of the potential uses of GO-Ag NPs and emphasizes the need for further research to develop more straightforward methods for their production and application.

Polyethylene glycol modified graphene oxide-silver nanoparticles nanocomposite as a novel antibacterial material with high stability and activity

Inorganic antibacterial nanomaterials play an increasingly important role in addressing the growing threat of drug-resistant bacteria. Graphene oxide-silver nanoparticles composite (GO-AgNPs), as a kind of inorganic nanomaterials, have excellent antibacterial properties, showing promising potential in biomedical field. However, GO-AgNPs are terribly prone to sedimentation due to aggregation in physiological solutions, along with its non-environmental issues during the synthesis process, seriously limits the antibacterial application of GO-AgNPs in the biomedical field. To solve this problem, herein, polyethylene glycol-graphene oxide-silver nanoparticles composite (GO-AgNPs-PEG) were prepared by modifying GO-AgNPs with polyethylene glycol to enhance their dispersion stability in physiological solutions. In addition, GO-AgNPs-PEG were prepared with using the natural product gallic acid as a reductant and stabilizer, exhibiting the characteristic of environmentally friendly. Meanwhile, the dispersion stability and antibacterial activity of GO-AgNPs-PEG were characterized by various technical methods, it was found that GO-AgNPs-PEG can be stably dispersed in a variety of physiological solutions (e.g., physiological saline, phosphate buffer solution, Luria-Bertani medium, Murashige and Skoog medium) for more than one week. Moreover, the antibacterial properties of GO-AgNPs-PEG in physiological solutions were significantly better than those of GO-AgNPs. Furthermore, it was discovered that the antibacterial mechanism of GO-AgNPs-PEG was probably associated to destroying the integrity of bacterial cell walls and membranes. The findings in this work can provide new ideas and references for the development of new inorganic antibacterial nanomaterials with stable dispersion in physiological solutions.

Inhibition of Coliforms and Escherichia coli Bacterial Strains in Water by 3D Printed CS/GO/AgNP Filtration Membranes

The effect of 3D printed modified Chitosan membranes on bacterial strains by water filtration system was explored in this study. Specifically, it focused on the characterisation of 3D printed Chitosan–graphene oxide–silver nanoparticles (CS–GO–AgNP) composite membranes and the effects of Dimethylacetamide (DMAc) used as co-solvent on the performance of the CS–GO–AgNP nanocomposites. It also examined the impact of GO–AgNP on the CS matrix for inhibition of Fecal Coliforms, Total Coliforms and Escherichia coli (E. coli) bacterial strains in contaminated surface water. The increase in DMAc concentration and subsequent reduction in CS mole fraction within the ink formulation resulted to wider distribution of AgNP across membrane surface, improvement in mechanical strength and surface hydrophilicity of the modified CS membranes. Similarly, increase in GO–AgNP concentration effectively reduced the spread of the identified microorganisms. Sample B-12 with 79% CS, 21% DMAc and 1.2 ml of GO–AgNP exhibited the highest inhibition of the bacterial strains, with more than 95% of Fecal and Total Coliforms suppressed or inactivated, while 99.9% of the E. coli bacterial cells were completely prevented, indicating that our 3D printed modified CS membranes can effectively be used for water treatment.

Multiple RNA Profiling Reveal Epigenetic Toxicity Effects of Oxidative Stress by Graphene Oxide Silver Nanoparticles in-vitro.

The increasing industrial and biomedical utilization of graphene oxide silver nanoparticles (GO-AgNPs) raises the concern of nanosafety: exposure to the AgNPs or GO-AgNPs increases the generation of reactive oxygen species (ROS), causes DNA damage and alters the expression of whole transcriptome including mRNA, miRNA, tRNA, lncRNA, circRNA and others. Although the roles of different RNAs in epigenetic toxicity are being studied during the last decade, but still we have little knowledge about the role of circle RNAs (circRNAs) in epigenetic toxicity. Rabbit fetal fibroblast cells (RFFCs) were treated with 0, 8, 16, 24, 32 and 48 μg/mL GO-AgNPs to test the cell viability and 24 μg/mL GO-AgNPs was selected as the experimental dose. After 24 h treatment with 24 μg/mL GO-AgNPs, the level of ROS, malondialdehyde (MDA), superoxide dismutase (SOD), intracellular ATP, glutathione peroxidase (GPx), and glutathione reductase (Gr) were measured in the RFFCs. High-throughput whole transcriptome sequencing was performed to compare the expression of circRNAs, long non-coding RNAs (lncRNA) and mRNA between 24 μg/mL GO-AgNPs-treated RFFCs and control cells. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was performed to validate the accuracy of circRNA sequencing data. Bioinformatics analyses were performed to reveal the potential functional roles and related pathways of differentially expressed circRNAs, lncRNA and mRNA and to construct a circRNA-miRNA-mRNA interaction network. We found that 57 circRNAs, 75 lncRNAs, and 444 mRNAs were upregulated while 35 circRNAs, 21 lncRNAs, and 186 mRNAs were downregulated. These differentially expressed genes are mainly involved in the transcriptional mis-regulation of cancer through several pathways: MAPK signaling pathway (circRNAs), non-homologous end-joining (lncRNAs), as well as PPAR and TGF-beta signaling pathways (mRNAs). These data revealed the potential roles of circRNAs in the GO-AgNPs induced toxicity through oxidative damage, which would be the basis for further research to determine their roles in the regulation of different biological processes.

Fabrication of poly (styrene-acrylate)/silver nanoparticle-graphene oxide composite antibacterial by in situ Pickering emulsion polymerization

Graphene oxide (GO) nanosheets decorated with silver nanoparticles (AgNPs) were easily synthesized by chemical reduction, and the prepared nanocomposite was then used as a stabilizer in the Pickering emulsion polymerization of poly (styrene-acrylate) to prepare PSA/AgNPs-GO composites. The AgNPs-GO nanocomposites were fully characterized by TEM, FTIR, Raman, SEM and XPS, which demonstrated that about 5–30 nm AgNPs with spherical, octahedral and cubic structures were decorated on the surface of wrinkled GO nanosheets. TEM photos and EDS spectrum of composites showed that the transparent GO nanosheets decorated with AgNPs were covered on the surface of PSA latexes and the AgNPs were uniformly dispersed on the surface of the PSA latexes without aggregation. The average diameter of composite latexes was obviously bigger than that of PSA latexes. However, the role of surfactant and the properties of hydrophilicity decreased the average diameter and WCA of composites while increasing the additions of AgNPs-GO nanocomposites. AFM images disclosed that wrinkled GO nanosheets decorated with AgNPs dispersed on the surface of composite films. XPS data proved clearly that silver was present only in metallic form and migration occurred during film-formation. TGA curves confirmed the composite film displayed better thermal stability than that of PSA. The results of antibacterial activity revealed that composite films had exhibited antibacterial properties against both E. coli and S. aureus, and the latter showed better antibacterial efficacy than the former. The nano-silver polyacrylate coatings with antibacterial activity explored in current work have wide application in the fields of wood coatings, leather finishing, and so on.

Identification of circular RNAs expression pattern in caprine fetal fibroblast cells exposed to a chronic non-cytotoxic dose of graphene oxide-silver nanoparticle nanocomposites.

The widespread use of graphene oxide-silver nanoparticle nanocomposites (GO-AgNPs) in biomedical sciences is increasing the chances of human and animal exposure to its chronic non-toxic doses. Exposure to AgNPs-related nanomaterials may result in the negative effect on the dam, fetus and offspring. However, there are only little available information for profound understanding of the epigenetic alteration in the cells and animals caused by low-dose chronic exposure of GO-AgNPs. The present study investigated the effect of 0.5μg/mL GO-AgNPs for 10weeks on the differential expression of circular RNAs (circRNAs) in caprine fetal fibroblast cells (CFFCs), and this dose of GO-AgNPs did not affect cell viability and ROS level. We predicted the functions of those differentially expressed (DE) circRNAs in CFFCs by bioinformatics analysis. Furthermore, we validated the expression of ten DE circRNAs using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) to ensure the reliability of the sequencing data. Our results showed that the DE circRNAs may potentially regulate the GO-AgNPs-inducing epigenetic toxicity through a regulatory network consisted of circRNAs, miRNAs and messenger RNAs (mRNAs). Therefore, the epigenetics toxicity is essential to assess the biosafety level of GO-AgNPs.

Synthesis of nanocomposites reduced graphene oxide-silver nanoparticles prepared by hydrothermal technique using sodium borohydride as a reductor for photocatalytic degradation of Pb ions in aqueous solution

Heavy metals are pollutants that are harmful to living things and the environment can be degraded by microbes or understood by other living things so that they can cause health problems. One of the heavy metals that is often found in wastewater is lead. Lead is widely used in the manufacture of batteries, metal products such as ammunition, cable coatings, Polyvinyl Chloride (PVC) tubing, solder, chemicals and dyes This use causes humans to be exposed to large amounts of lead. One method to deal with lead pollution is to use photocatalysts. Photocatalysts react with heavy metals and reduce them so that the level of toxicity becomes lower than before through photocatalytic reactions. In this study, synthesis of reduced graphene oxide/silver nanoparticle nanoparticles was performed by facile hydrothermal methods for photocatalytic degradation of Pb ion. The characterization results indicate that the synthesis has been successfully carried out. The successful result of rGO/AgNPs nanocomposites synthesis was proved by several techniques such as X-ray diffraction analysis, Raman, UV-Vis spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray analysis (EDX). This indicates the presence of these groups in the graphene oxide and rGO/AgNPs samples, respectively. The resulting rGO/AgNPs nanocomposite has an absorbance peak at a wavelength of 267 nm. The diffraction peaks for nanocomposites rGO/AgNPs and their Miller indices were 38.08° (111), 44.16° (200), 64.44° (220), and 77.44° (311). The Raman spectra of rGO/AgNPs exhibits D bands at 1334,13 with intensity of 630,60 cm−1 and G band at 1594,61 with intensity of 477,29 cm−1. The ID/IG ratio rGO/AgNPs-NaBH4 is ~1,32. Furthermore, the photocatalytic activity test results showed that the rGO/AgNPs nanocomposite was able to reduce Pb2+ to Pb with a maximum exposure time of 1.5 hours

Biosynthesis of silver nanoparticles using Allium sativum extract assisted by solar irradiation in a composite with graphene oxide as potent adsorbents

The present works describe a stable and facile biosynthesis of silver nanoparticles (AgNPs) from Allium sativum (A. sativum) cloves extract deposited on graphene oxide (GO). The AgNPs with different concentrations of [Ag(NH3)2]+ solution were synthesized under solar irradiation to catalyze the growth of AgNPs prior to the deposition on GO. Their adsorptivity was tested against methylene blue (MB) dye in aqueous media. Characterization analyses revealed that the silver nanoparticle-graphene oxide, Ag:GO-100 (S) nanocomposites were crystalline with asymmetrical spherical-shaped and well-dispersed on GO surfaces. The anchoring of AgNPs on GO sheets acts as spacers for the enhanced nanocomposites’ surface area and synergistically achieved almost a complete removal of MB dye in 5 min. The best rate constant of 4.97816 g mg−1 min−1 was obtained from the pseudo second-order kinetic model. The spontaneous adsorption mechanism was affirmed, and the nanocomposite potential could be exploited as an efficient, cost-effective, and feasible approach in the remediation of contaminated water, as a result of their outstanding performances.

Preparation of poly(ε-caprolactone) nanofibrous mats incorporating graphene oxide-silver nanoparticle hybrid composite by electrospinning method for potential antibacterial applications

In this study, poly(ε-caprolactone) based fibrous mats incorporating graphene oxide-silver hybrid nanocomposite as a nanofiller were successfully prepared by electrospinning method for potential biomedical applications. First, graphene oxide-silver nanoparticles (GO-AgNPs) were synthesized and the obtained GO-AgNPs nanohybrid was characterized by different analytical techniques. It was observed that the obtained AgNPs, with an average size of 5 ± 0.5 nm and spherical shape, were uniformly anchored on the surface of GO. Then, the synthesized GO-AgNPs were added into PCL to improve its tensile and bactericidal performances. The structural, morphological, mechanical and wettability properties of PCL-based fibrous mats as well as the release of silver ion release from PCL matrix were examined. Based on the results, we found that the addition of GO to the PCL-3.0%Ag nanofibers resulted in increased hydrophilicity, tensile strength and resistance to elastic deformation, and the PCL-GO-3.0%Ag sample also had a significantly higher release of silver ions. Besides, PCL-GO–3.0%Ag mats showed good antibacterial activity against Staphylococcus aureus and Escherichia coli compared to the PCL, PCL-GO and PCL-Ag nanofibrous mats. In summary, this study showed that PCL-GO–3.0%Ag nanofibrous mats could be a promising biomaterial for potential antibacterial applications.

Enhanced Antibacterial Activity through Silver Nanoparticles Deposited onto Carboxylated Graphene Oxide Surface.

The strong bactericidal action of silver nanoparticles (AgNPs) is usually limited by their degree of aggregation. Deposition of AgNPs onto a graphene oxide (GO) surface to generate GO-Ag hybrids has been shown to be an effective method of controlling these aggregation problems. In this sense, a novel carboxylated graphene oxide–silver nanoparticle (GOCOOH-Ag) material has been synthesized, and their antibacterial and biofilm formation inhibitions have been studied. AgNPs decorating the GOCOOH surface achieved an average size of 6.74 ± 0.25 nm, which was smaller than that of AgNPs deposited onto the GO surface. In addition, better distribution of AgNPs was achieved using carboxylated material. It is important to highlight the main role of the carboxylic groups in the nucleation and growth of the AgNPs that decorate the GO-based material surface. In vitro antibacterial activity and antibiofilm-forming action were tested against Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Both GO-Ag and GOCOOH-Ag reduced bacterial growth, analyzed by time–kill curves. However, the minimum inhibitory concentration and the minimum bactericidal concentration of GOCOOH-Ag were lower than those of GO-Ag for all strains studied, indicating that GOCOOH-Ag has better antibacterial activity. In addition, both nanomaterials prevent biofilm formation, with a higher reduction of biofilm mass and cell viability in the presence of GOCOOH-Ag. The carboxylation functionalization in GO-based materials can be applied to improve the bactericidal and antibiofilm-forming action of the AgNPs.

In Situ Green Synthesis of Graphene Oxide-Silver Nanoparticles Composite with Using Gallic Acid.

The adoption of plant-derived natural products to synthesize metal nanoparticles and their complexes has the advantages of mild reaction conditions, environmental protection, sustainability and simple operation compared with traditional physical or chemical synthesis methods. Herein, silver nanoparticles (AgNPs) were in situ synthesized on the surface of graphene oxide (GO) by a “one-pot reaction” to prepare graphene oxide-silver nanoparticles composite (GO-AgNPs) based on using AgNO3 as the precursor of AgNPs and gallic acid (GA) as the reducing agent and stabilizer. The size and morphology of GO-AgNPs were characterized by ultraviolet-visible spectrophotometer (Uv-vis), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), X-ray diffractometer (XRD) and dynamic light scattering (DLS). The effects of pH, temperature, time and material ratio on the synthesis of GO-AgNPs were investigated experimentally. The results showed that ideal GO-AgNPs could be prepared under the conditions of pH = 9, 45°C, 2 h and the 2:1 of molar ratio of AgNO3 to GA. The AgNPs within GO-AgNPs are highly crystalline spherical particles with moderate density on the surface of GO, and the size of AgNPs is relatively uniform and determined to be about 8.19 ± 4.21 nm. The research results will provide new ideas and references for the green synthesis of metal nanoparticles and their complexes using plant-derived natural products as the reducing agent and stabilizer.

Nanocomposites of Graphene Oxide-Silver Nanoparticles for Enhanced Antibacterial Activity: Mechanism of Action and Medical Textiles Coating.

The resistance of microorganisms to antibiotics is a crucial problem for which the application of nanomaterials is among a growing number of solutions. The aim of the study was to create a nanocomposite (composed of graphene oxide and silver nanoparticles) with a precise mode of antibacterial action: what enables textiles to be coated in order to exhibit antibacterial properties. A characterization of nanomaterials (silver nanoparticles and graphene oxide) by size distribution, zeta potential measurements, TEM visualization and FT-IR was performed. The biological studies of the nanocomposite and its components included the toxicity effect toward two pathogenic bacteria species, namely Pseudomonas aeruginosa and Staphylococcus aureus, interaction of nanomaterials with the outer layer of microorganisms, and the generation of reactive oxygen species and lipid peroxidation. Afterwards, antibacterial studies of the nanocomposite’s coated textiles (cotton, interlining fabric, polypropylene and silk) as well as studies of the general toxicity towards a chicken embryo chorioallantoic membrane model were conducted. The toxicity of the nanocomposite used was higher than its components applied separately (zones of growth inhibition for P. aeruginosa for the final selected concentrations were as follows: silver nanoparticles 21 ± 0.7 mm, graphene oxide 14 ± 1.9 mm and nanocomposite 23 ± 1.6 mm; and for S. aureus were: silver nanoparticles 27 ± 3.8 mm, graphene oxide 14 ± 2.1 mm, and nanocomposite 28 ± 0.4 mm. The viability of P. aeruginosa and S. aureus after treatment with selected GO-Ag decreased to 27% and 31%, respectively, compared to AgNPs, when the viability of both species was 31% and 34%, accordingly). The coated textiles showed encouraging antibacterial features without general toxicity towards the chicken embryo chorioallantoic membrane model. We demonstrated that graphene oxide might constitute a functional platform for silver nanoparticles, improving the antibacterial properties of bare silver. Due to the application of the nanocomposite, the textiles showed promising antibacterial features with a low general toxicity, thereby creating a wide possibility for them to be used in practice.

Surface Modification of Commercial Cotton Yarn as Electrode for Construction of Flexible Fiber-Shaped Supercapacitor

In this study, we report on the rational design and facile preparation of a cotton-reduced graphene oxide-silver nanoparticle (cotton-RGO-AgNP) hybrid fiber as an electrode for the building of a flexible fiber-shaped supercapacitor (FSSC). It was adequately characterized and found to possess a well-defined core−shell structure with cotton yarn as a core and a porous RGO-AgNP coating as a shell. Thanks to the unique morphological features and low electrical resistance (only 2.3 Ω·cm−1), it displayed attractive supercapacitive properties. When evaluated in a three-electrode setup, this FSSC electrode delivered the highest linear and volumetric specific capacitance of up to ca. 12.09 mF·cm−1 and ca. 9.67 F·cm−3 with a satisfactory rate capability as well as a decent cycling stability. On the other hand, an individual parallel symmetric FSSC cell constructed by this composite fiber fulfilled the largest linear and volumetric specific capacitance of ca. 1.67 mF·cm−1 and ca. 0.67 F·cm−3 and offered the maximum energy density, as high as ca. 93.1 μWh·cm−3, which outperformed a great number of graphene- and textile yarn-based FSSCs. Impressively, bending deformation brought about quite a limited effect on its electrochemical behaviors and almost no capacitance degradation took place during the consecutive charge/discharge test for over 10,000 cycles. Consequently, these remarkable performances suggest that the currently developed cotton-RGO-AgNP fiber has considerable application potential in flexible, portable and wearable electronics.

Colorimetric and “turn-on” fluorescence detection of saccharin using silver nanoparticles-graphene oxide composite

Saccharin (SAC) is a synthetic sweetener used in soft drinks and candies. Consumption of excess SAC leads to several health problems. Therefore, developing a simple method to detect its concentration in food stuffs and soft drinks is very important. The present study describes a simple colorimetric method for SAC determination using graphene oxide-silver nanoparticles (GO-AgNPs) composite solution. The yellow color GO-AgNPs was changed to reddish brown while adding 600 μM SAC and the emission of GO was “turn off” after the formation of AgNPs. However, the emission was “turn on” after the addition of SAC. This was ascribed to the strong interaction between sulfonamide groups of SAC with AgNPs, resulting the leaching of AgNPs from GO surface. The emission intensity increases linearly when SAC concentration increases from 500 nM to 1 mM with R2 = 0.9971 and the limit of detection was 0.7 mg L−1 (S/N = 3). The present GO-AgNPs composite was also used to selectively determine SAC containing 1400-fold higher concentration of interferents. Finally, the real sample analysis was carried out by determining SAC in candies and soft drinks by using GO-AgNPs.