GO-Ag NPs Research Articles

Green synthesis of novel chitosan-graphene oxide-silver nanoparticle nanocomposite for broad-spectrum antibacterial applications

Abstract In this study, a novel nanocomposite composed of chitosan, graphene oxide, and silver nanoparticles (CS-GO-Ag NPs) is presented and synthesized using pulsed laser ablation. Characterization techniques, including X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy EDX, and UV-visible spectroscopy, confirm successful synthesis. The XRD results reveal that the CS-GO-Ag NPs exhibit crystalline structures with an average crystallite size of approximately 30 nm. FE-SEM analysis shows a heterogeneous mixture of nanoparticles, ranging in size from 32.38 to 174.9 nm. The EDX spectra elucidate the elemental composition, while UV-Vis spectroscopy indicates strong interactions among the components, yielding a direct bandgap of 2.33 eV and an indirect bandgap of 1.2 eV, suggesting efficient light absorption and emission for applications in Light emitted Diode (LEDs) and solar cells. Furthermore, the CS-GO-Ag NPs nanocomposite displays enhanced antibacterial activity against both gram-negative and gram-positive bacteria when it compared to its individual components. According to characterization tests, well-dispersed silver nanoparticles were formed into a ternary nanocomposite, successfully. The enhanced antibacterial capabilities including increased bacterial cell membrane disruption and oxidative stress can be attributed to the synergistic interaction between the components. The outcomes highlight the CS- GO-Ag NPs nanocomposite's potential as a promising antimicrobial agent for numerous applications including the biomedical fields and water treatment industries.

Evaluation of thermal, antimicrobial, antioxidant, anticancer, and wound healing properties of GO-Ag containing nanocomposites based on CS- PPFOEMA blend

The new methacrylate-based polymer, poly (pentafluorophenyl)methyl 2-methylprop-2-enoate (PPFOEMA), was blended with CS biopolymer by in situ/hydrothermal method. The nanohybrid filler containing commercial graphene oxide (GO) and biosynthesized silver nanoparticles (AgNP) was incorporated into the CS-PPFOEMA mixture by hydrothermal treatment. PFOEMA and PPFOEMA were characterized by FTIR and NMR techniques, while the nanocomposites were characterized by FT-IR, XRD, SEM, and EDX analysis. The thermal properties of the materials were determined by TGA and DSC techniques. According to TGA data, PPFOEMA caused a decrease in the thermal stability of CS. However, the thermal stability increased after the incorporation of GO-AgNPs into the blend by hydrothermal method. The initial degradation temperature of the CS-PPFOEMA blend, which was 240 °C, increased to 260 °C after adding 7 % GO-Ag. The glass transition temperature (Tg) of CS decreased after blending and after the incorporation of GO-AgNPs into the blend. The antioxidant capacity (TAC) of the GO-AgNPs mixture was close to that of CS-PPFOEMA, but TAC levels increased with the inclusion of GO-AgNPs in the CS-PPFOEMA blend. While the cytotoxicity of CS in A549 cells was 100 μg/mL, it became 100 μg/mL after blending. Additionally, when GO-Ag was added to the CS-PPFOEMA mixture at different rates, toxic effects were observed starting from 100 μg/mL concentration. The nanocomposite containing 3 % GO-Ag was highly influential in wound healing. The results are promising for using nanocomposites formed by blending CS with synthetic PPFOEMA and adding GO-Ag NPs as safe biomaterials.

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.

Prismatic Silver Nanoparticles Decorated on Graphene Oxide Sheets for Superior Antibacterial Activity.

Spherical silver nanoparticles (Ag NPs) and silver nanoprisms (Ag NPrsms) were synthesized and decorated on graphene oxide (GO) nanosheets. The Ag contents were 29% and 23% in the GO–Ag NPs and GO–Ag NPrsms, respectively. The Ag NPrsms exhibited stronger (111) crystal signal than Ag NPs. The GO–Ag NPrsms exhibited higher Ag (I) content (75.6%) than GO-Ag NPs (69.9%). Increasing the nanomaterial concentration from 25 to 100 µg mL−1 improved the bactericidal efficiency, and the antibacterial potency was in the order: GO–Ag NPrsms > GO–Ag NPs > Ag NPrsms > Ag NPs > GO. Gram-positive Staphylococcus aureus (S. aureus) was more vulnerable than Gram-negative Escherichia coli (E. coli) upon exposure to these nanomaterials. The GO–Ag NPrsms demonstrated a complete (100%) bactericidal effect against S. aureus at a concentration of 100 µg mL−1. The GO–Ag composites outperformed those of Ag or GO due to the synergistic effect of bacteriostatic Ag particles and GO affinity toward bacteria. The levels of reactive oxygen species produced in the bacteria–nanomaterial mixtures were highly correlated to the antibacterial efficacy values. The GO–Ag NPrsms are promising as bactericidal agents to suppress biofilm formation and inhibit bacterial infection.

Novel antibacterial hydrogels based on gelatin/polyvinyl-alcohol and graphene oxide/silver nanoconjugates: formulation, characterization, and preliminary biocompatibility evaluation

Antibiotic resistance has become a major public health problem generated by their excessive and inappropriate use. This is worrisome because multiple microbial infections that could traditionally be treated without major complications are now considerably challenging to treat. In this regard, research in this field has been focused on searching for new molecules capable of arresting these microbial infections with high effectiveness, including antimicrobial peptides (AMP) and various nanomaterials. Here, we proposed a novel topical hydrogel treatment based on a polymeric network of gelatin-polyvinyl alcohol-hyaluronic acid encapsulating a graphene oxide (GO) nanoconjugate on which silver nanoparticles (Ag NPs) have been grown. This treatment is intended to be stable, biocompatible, non-toxic, pleasant to skin contact, provide bioavailability of the active agent for a prolonged period in the affected skin area where its application is required and inhibit microbial growth effectively. The nanocomposite hydrogels were characterized in terms of microstructure, thermal resistance, rheological behavior, particle size distribution, texture profile and physical stability, as well as a one-month accelerated stability study. The satisfactory results in terms of physical chemistry, stability on storage modulus (G’), TSI values, and microstructure allowed choosing some points of the experimental design to encapsulate the GO-Ag NPs nanoconjugates. The biological evaluation of these nanocomposites showed that the treatments are biocompatible as they have a very low hemolytic effect (less than 5%) and a moderate platelet aggregating capacity (35%–45%). Finally, 100% of bacterial growth was inhibited by the action of the topical nanocomposite hydrogel treatments. These results led to affirm that these treatments can have an excellent performance in this application as well as in wound healing and dressing, bioadhesives, tissue engineering, and other biomedical applications.

Studying the effect of the number of laser pulses on the structure, morphology, and optical properties for a thin film of GO-Ag nanocomposites

In this paper, studying the effect of the different numbers of laser pulses on graphene oxide -silver nanoparticles (GO-Ag NPs) thin film prepared by the pulse laser deposition (PLD) on silicon and quartz substrates. The laser using in PLD is an ND-YAG laser with a wavelength (1064 nm)m with a repetition rate of 6 Hz with a laser pulse duration (9 ns). Atomic force microscopy AFM and XRD using for analysis of the thin film, the results showed the possibility of preparing thin films with different sizes of granule and crystalline sizes on the nanoscale. Also, show that the granular size and crystal size of the nanoparticles decrease with the increase in the number of laser pulses with the constant energy. Moreover, the optical properties measurements showed that the absorbance and absorption coefficient increase with the increase in the number of pulses when the energy is constant, while the energy gap decreases with increasing the number of pulses These results were promises to producing the thin film for Graphene oxide-silver nanocomposites for different applications compatible with it.

Synthesis, Physical, Mechanical and Antibacterial Properties of Nanocomposites Based on Poly(vinyl alcohol)/Graphene Oxide-Silver Nanoparticles.

The design of new materials with antimicrobial properties has emerged in response to the need for preventing and controlling the growth of pathogenic microorganisms without the use of antibiotics. In this study, partially reduced graphene oxide decorated with silver nanoparticles (GO–AgNPs) was incorporated as a reinforcing filler with antibacterial properties to poly(vinyl alcohol) (PVA) for preparation of poly(vinyl alcohol)/graphene oxide-silver nanoparticles nanocomposites (PVA/GO–AgNPs). AgNPs, spherical in shape and with an average size of 3.1 nm, were uniformly anchored on the partially reduced GO surface. PVA/GO–AgNPs nanocomposites showed exfoliated structures with improved thermal stability, tensile properties and water resistance compared to neat PVA. The glass transition and crystallization temperatures of the polymer matrix increased with the incorporation of the hybrid. The nanocomposites displayed antibacterial activity against Staphylococcus aureus and Escherichia coli in a filler content- and time-dependent manner. S. aureus showed higher susceptibility to PVA/GO–AgNPs films than E. coli. Inhibitory activity was higher when bacterial cells were in contact with nanocomposite films than when in contact with leachates coming out of the films. GO–AgNPs based PVA nanocomposites could find application as wound dressings for wound healing and infection prevention.

Synergistic Antibacterial Activity of Silver-Loaded Graphene Oxide towards Staphylococcus Aureus and Escherichia Coli.

In this study, the physicochemical and surface properties of the GO–Ag composite promote a synergistic antibacterial effect towards both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. Aureus) bacteria. GO–Ag NPs have a better bactericidal effect on E. coli (73%) and S. Aureus (98.5%) than pristine samples (pure Ag or GO). Transmission electron microscopy (TEM) confirms that the GO layers folded entire bacteria by attaching to the membrane through functional groups, while the Ag NPs penetrated the inner cell, thus damaging the cell membrane and leading to cell death. Cyclic voltammetry (CV) tests showed significant redox activity in GO–Ag NPs, enabling good catalytic performance towards H2O2 reduction. Strong reactive oxygen species (ROS) in GO–Ag NPs suggests that ROS might be associated with bactericidal activity. Therefore, the synergy between the physicochemical effect and ROS production of this material is proposed as the mechanism of its antibacterial activity.

Antibacterial Silver Nanoparticles Supported on Graphene Oxide with Reduced Cytotoxicity

The effect of graphene oxide (GO) on both the antibacterial and cytotoxicity behavior of silver nanoparticles (Ag NPs) has been studied. Ag NPs supported on GO were synthesized by two methods, ex situ and in situ. These nanocomposites were characterized by transmission electron microscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The antibacterial activity of the nanomaterials was evaluated against Escherichia coli and Staphylococcus aureus by the disk-diffusion method and dynamic contact assays. While GO flakes showed antibacterial behavior only in the dynamic contact test, both GO-Ag NPs nanohybrids eradicated bacteria independent of the condition. Noteworthily, the high cytotoxicity of Ag NPs to human-derived cells was dramatically decreased by the GO layers in the nanocomposite. The in situ hybrid particles showed the lowest cytotoxicity without losing the strong antibacterial effect. These results demonstrate that growth of Ag NPs on GO layers could enable the development of a new family of antibacterial materials with low cytotoxicity to human cells.

Novel graphene oxide-silver nanorod composites with enhanced photocatalytic performance under visible light irradiation

The catalytic properties of graphene oxide (GO) - Ag nanocrystals are investigated to understand the effects of the size and morphology in the selective oxidation of cyclohexane. The GO-Ag nanoparticle composites (GO-Ag NPs) with smaller size show higher catalytic activity than those with bigger Ag nanoparticles, while GO-Ag nanorod composites (GO-Ag NRs) perform better catalytic property than GO-Ag NPs. The highest cyclohexane conversion of 37.0% with the selectivity of 94.0% to cyclohexanol and cylohexanone (KA oil) is obtained by using the photocatalysts of GO-Ag NRs under solar light irradiation at room temperature. The higher catalytic activity of GO-Ag NRs is caused by the stronger Surface Plasmon Resonance (SPR) effect of Ag NRs, and its facilitated generation of ·OH radicals. Both GO-Ag NPs and GO-Ag NRs possess great durability without evident decline of conversion efficiency and selectivity after five repeated consecutive runs. The research and finding in this work may pave a way for the development of high-performance catalysts and green chemical production processes.

Preparation of silver nanoparticles loaded graphene oxide nanosheets for antibacterial activity

A simple, facile method to fabricate successfully silver nanoparticle (AgNPs) decorated on graphene oxide (GO) layers via grafted thiol groups. Samples were prepared with different concentrations of AgNO3. Resulting AgNPs were quasi-spherical in shape and attached on the layers of GO. Physical properties were confirmed by X-ray diffraction (XRD), zeta potential, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectra, thermogravimetric analyzer (TGA), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM). Antimicrobial test was effectively showed using MRSA (Staphylococcus areus). The GO-Ag NPs with appropriate Ag NPs content of 0.2 M AgNO3 exhibited the strongest antibacterial activity at 48.77% inhibition after 4 hours incubation.

Graphene Oxide/Silver Nanohybrid as Multi-functional Material for Highly Efficient Bacterial Disinfection and Detection of Organic Dye

In this work, a multi-functional hybrid system consisting of graphene oxide and silver nanoparticles (GO-Ag NPs) was successfully synthesized by using a two-step chemical process. We firstly demonstrated noticeable bactericidal ability of the GO-Ag hybrid system. We provide more chemo-physical evidence explaining the antibacterial behavior of GO-Ag nanohybrid against Gram-negative Escherichia Coli and Gram-positive Staphylococcus aureus in light of ultrastructural damage analyses and Ag1+ ions release rate onto the cells/medium. A further understanding of the mode of antimicrobial action is very important for designing and developing advanced antimicrobial systems. Secondly, we have also demonstrated that the GO-Ag nanohybrid material could be used as a potential surface enhanced Raman scattering (SERS) substrate to detect and quantify organic dyes, e.g., methylene blue (MB), in aqueous media. Our findings revealed that the GO-Ag hybrid system showed better SERS performance of MB detection than that of pure Ag-NPs. MB could be detected at a concentration as low as 1 ppm. The GO-Ag-based SERS platform can be effectively used to detect trace concentrations of various types of organic dyes in aqueous media. With the aforementioned properties, the GO-Ag hybrid system is found to be very promising as a multi-functional material for advanced biomedicine and environmental monitoring applications.

Theoretical Design and Experimental Realization of Quasi Single Electron Enhancement in Plasmonic Catalysis.

By a combination of theoretical and experimental design, we probed the effect of a quasi-single electron on the surface plasmon resonance (SPR)-mediated catalytic activities of Ag nanoparticles. Specifically, we started by theoretically investigating how the E-field distribution around the surface of a Ag nanosphere was influenced by static electric field induced by one, two, or three extra fixed electrons embedded in graphene oxide (GO) next to the Ag nanosphere. We found that the presence of the extra electron(s) changed the E-field distributions and led to higher electric field intensities. Then, we experimentally observed that a quasi-single electron trapped at the interface between GO and Ag NPs in Ag NPs supported on graphene oxide (GO-Ag NPs) led to higher catalytic activities as compared to Ag and GO-Ag NPs without electrons trapped at the interface, representing the first observation of catalytic enhancement promoted by a quasi-single electron.

Graphene oxide–silver nanoparticle membrane for biofouling control and water purification

The removal of bacteria and other organisms from water is an important process, not only for water purification but also biofouling control in membrane filtration. In this study, we report an antibiofouling membrane by fabricating graphene oxide–silver nanoparticles (GO–AgNPs) composite onto cellulose acetate (CA) membrane. Microscopic analysis showed that the silver nanoparticles (AgNPs) retained its nanostructure morphology on the membrane surface. The contact angle results indicated that the hydrophilicity of the membrane was enhanced by the modification of modified GO–AgNPs. Under the continuous filtration test, the relative flux drop over GO–AgNPs composite membrane was only 46%, which was much lower than that the CA membrane (88%) after 24h filtration. Moreover, the flux of the GO–AgNPs composite membrane is higher than both the GO membrane and silver membrane in the filtration process. The presence of GO–AgNPs composite on the membrane exhibited a strong antibacterial activity, leading to an inactivation of 86% Escherichia coli after contacting with the membrane for 2h. This study may have great potential in developing high-performance antibiofouling membrane for membrane separation processes.

Antibacterial hybrid cellulose–graphene oxide nanocomposite immobilized with silver nanoparticles

An antibacterial hybrid GO–AgNPs cellulose membrane was prepared. Incorporation of GO created a more porous structure of the regenerated cellulose membrane, improved the deposition of AgNPs and demonstrated an effective antibacterial activity with minimal release of Ag ions.

Optical engineering of uniformly decorated graphene oxide nanoflakes via in situ growth of silver nanoparticles with enhanced plasmonic resonance.

A nanocomposite of silver-nanoparticle-decorated graphene oxide (GO-Ag NPs), enhanced by the surface plasmon resonance (SPR) effect, improved the performance of polymer solar cells (PSCs). The GO-Ag NPs were fabricated in situ via ultraviolet (UV) irradiation (254 nm) of GO and an aqueous solution of AgNO3. The photoexcited GO accelerated reduction of Ag(+) ions into silver nanoparticles (Ag NPs) upon UV irradiation, and the Ag NPs spontaneously deposited on the GO nanoflakes because the numerous functional groups on GO enable efficient adsorption of Ag(+) ions and Ag NPs via electrostatic interactions. The strong coupling between the SPR effect of GO-Ag NPs and incident light offers the probability of improved light absorption and corresponding exciton generation rate with enhanced charge collection, resulting in significant enhancement in short-circuit current density and power conversion efficiency (PCE). Therefore, the PCE of PSCs based on poly[4,8-bis(2-ethylhexylthiophene-5-yl)-benzo[1,2-b:4,5-b]dithiophene-2,6-diyl]-alt-[2-(2-ethylhexanoyl)thieno[3,4-b]thiophen-4,6-diyl] and [6,6]-phenyl C71-butyric acid methyl ester has been substantially elevated to 7.54% from 6.58% by introducing GO-Ag NPs at the indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid interface. In addition, the excellent properties of GO-Ag NPs, including its simple preparation, processability in aqueous solution, cost-effectiveness, and sustainability, make it suitable for the roll-to-roll manufacturing of PSCs.