Silver Nanoparticle-decorated Graphene Oxide Research Articles

Tuning the optical and electrical properties by gamma irradiation of silver nanoparticles decorated graphene oxide on glutaraldehyde crosslinked polyvinyl alcohol matrix

In this study, we propose a facile in-situ approach to fabricate a silver (Ag) NPs decorated graphene oxide (GO) blended with glutaraldehyde (GA) crosslinked polyvinyl alcohol (PVA) matrix, resulting in a PVA/GO-Ag/GA nanocomposite. We investigated how gamma radiation affected the optical and electrical properties of the resulting nanocomposites. Our study reveals that exposure to gamma radiation decreases the band gap of PVA/GO-Ag/GA from 6.06 to 3.35 eV for a 2 kGy dose. The direct current (dc) electrical conductivity was measured to be 2.30 × 10−5 S cm−1 for a 2 kGy dose. Additionally, Jonscher's power law analysis of the alternating current (ac) conductivity behavior suggests that the conduction mechanism in the samples is most likely due to charge carrier transport after gamma irradiation. In conclusion, our findings demonstrate that irradiating PVA/GO-Ag/GA nanocomposites with gamma wavelengths yields tunable electrical and optical properties, making them potential candidates for optoelectronic and electromagnetic applications.

Tuning the energy storage performance of graphene oxide-based nanocomposite films by encapsulating silver nanoparticles

In the current designed study, we explore the dielectric and energy storage performance of silver nanoparticle decorated graphene oxide nanocomposites incorporated into chitosan blended with poly (1-vinylpyrrolidone-co-vinyl acetate) in comparison with only graphene oxide nanocomposite doped into the same blend matrix. A sustainable and eco-friendly green route approach was used to form the silver nanoparticle decorated graphene oxide nanocomposites. The nanocomposite films so fabricated using the solvent evaporation method, were subjected to various characterisation techniques such as X-ray diffraction analysis, Fourier transform infrared spectroscopy, thermal analysis, surface morphology and impedance spectroscopy. Slight decrease in crystallinity (44.3 %), difference in the positioning of infrared bands, thermal stability (up to ∼77 °C) and evenly distributed morphology depict the advantage of silver coating over graphene oxide nanoparticles in the blended nanocomposite films. A boost in the dielectric properties and energy storage ability was displayed by the silver encapsulated graphene oxide reinforced nanocomposite blend films. The dielectric properties were examined by using a Nyquist plot (Bulk resistance - 1.01 × 104 Ω). An ionic conductivity of 1.044 × 10−4 S/cm and a DC conductivity of 1.196 × 10‐−4 S/cm was observed. Of note, it can be inferred that silver nanoparticle decorated graphene oxide nanocomposites impart tremendous electrical properties to the chitosan/poly (1-vinylpyrrolidone-co-vinylacetate) films, enabling them to be used in energy storage applications.

Fabrication of silver nanoparticle decorated graphene oxide membranes for water purification, antifouling and antibacterial applications

The quality of portable water is adversely affected by inadequate wastewater treatment, increase in domestic & industrial waste, and microbial contamination of surface water sources. Purification techniques such as sedimentation, precipitation, filtration, and ion exchange can be employed to recover clean water from various impurities. Among these, membrane-based purification methods have become more appealing in recent years due to its cost-effective and energy-saving features. However, fouling is a ubiquitous problem in membrane-based purification technologies, which leads to reduced water permeation and quality. Present study embodies the development of silver decorated graphene oxide coated nylon membrane with remarkable antibacterial and antifouling properties. Antibacterial analysis of bacteria Staphylococcus aureus and Escherichia coli, validates that higher concentration of silver in GO (GO A500) composites hinder the growth of bacteria. The antifouling properties of GO A500 membrane showed flux recovery ratio of 96 % with irreversible fouling ratio of 3 % during the filtration of BSA (Bovine serum albumin) protein. Further fabricated composite membrane exhibited pure water flux of 46.7 L m−2 h−1 with dye removal rate of 95 %, 88 % and 85 % for Congo red, Rhodamine-B and Methylene blue respectively. Catalytic studies conducted on GO A500 membrane demonstrated the efficacy of their antifouling properties. The investigations revealed that the composite (GO A500) membrane has excellent antibacterial and antifouling properties, making it a suitable option for wastewater treatment applications.

Enhanced photo-driven ion pump through silver nanoparticles decorated graphene oxide membranes

Enhanced photo-driven ion pump through silver nanoparticles decorated graphene oxide membranes

Synthesis, characterization, and antibacterial activity investigation of silver nanoparticle-decorated graphene oxide

Herein, silver/graphene oxide (Ag/GO) nanocomposite was fabricated by co-precipitation with green reducing agent and then was characterized with modern analytical techniques. The antibacterial activities were conducted via the effects of Ag/GO concentration, time, and pH. Results show that silver nanoparticles were uniformly distributed on the GO sheets nanosized of 17.65 ± 4.76 nm. The antibacterial performance was optimized at pH 5.6, eradicating P. aeruginosa in 180 min at 50 µg/mL Ag/GO concentration and S. aureus in 480 min at 300 µg/mL Ag/GO. This demonstrates the potential of Ag/GO as an antibacterial nanocomposite material.

Silver nanoparticles decorated graphene oxide nanocomposite for bone regeneration applications

Different ultra-lightweight carbon nanostructures with superb mechanical properties have made them attractive materials for reinforcing nanocomposites. However, the preparation of an ideal bone reinforcement is still a challenging task. Therefore, in the present study, a simple wet chemistry method was employed to synthesize silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite as potential reinforcement in orthopedic applications. A well-dispersed nearly oval-shaped AgNPs with the mean size of 9 ± 6 nm were homogeneously formed on the surface of GO due to its supporting role in preventing agglomeration of fine particles. The results of the antibacterial activities revealed that the anchor of AgNPs on the surface of GO improved its antibacterial properties, in which the composite structure exhibited higher antibacterial activity against Escherichia coli (E. coli) than Staphylococcus aureus (S. aureus) bacteria. The proposed protocol can keep steady the scattering of the AgNPs in nanocomposite and prolong the antibacterial activity of the system. Highlights AgNPs-GO nanocomposite was prepared via a facile wet chemistry approach. AgNPs (9 ± 6 nm) were homogeneously formed on GO. GO dictated the formation of nearly oval AgNPs in the system. The highest reactivity was found to be -0.315 eV.atom−1. Nanocomposite showed higher antibacterial activity versus E. coli than S. aureus bacteria.

Voltammetric aptasensor for thrombin by using a gold microelectrode modified with graphene oxide decorated with silver nanoparticles.

A sensitive electrochemical aptasensor was developed for the determination of thrombin. It is based on signal amplification by using graphene oxide (GO) decorated with silver nanoparticles (AgNP) and placed on a microelectrode. The graphene oxide decorated with silver nanoparticles (AgNP-GO) was synthesized by chemical reduction and then modified with a thrombin-binding aptamer 1 (TBA1; a 29-mer) carrying a 3'-terminal thiol group. It was immobilized on the AgNP-GO by self-assembled monolayer technique to form the signaling probe (TBA1-AgNP-GO). A capture thrombin-binding aptamer 2 (TBA-2; a 15-mer) carrying a 3'-terminal thiol group was self-assembled onto the surface of the gold electrode. After binding of thrombin and the signaling probe, a sandwich of type TBA2-thrombin-TBA1-AgNP-GO is formed. The square wave voltammetric signal of the AgNP is then recorded. The electrochemical oxidation signal (measured at 0.21V vs. Ag/AgCl) increases linearly with the concentration of thrombin in the range from 0.05nmol·L-1 to 5nmol·L-1 with a detection limit of 0.03nmol·L-1 (at S/N= 3). The aptasensor is highly specific and not affected by other proteins. It was successfully applied to the determination of thrombin in spiked human serum samples. Graphical abstract A sensitive electrochemical aptasensor for thrombin was developed based on the signal amplification of silver nanoparticles decorated graphene oxide at an ultramicroelectrode.

Visual electrochemiluminescence biosensing of aflatoxin M1 based on luminol-functionalized, silver nanoparticle-decorated graphene oxide

A sensitive electrochemiluminescence (ECL) aptasensor for aflatoxin M1 (AFM1) detection by a closed bipolar electrode (BPE) array has been introduced. The thiolated AFM1 aptamer was immobilized on gold nanoparticle-coated magnetic Fe3O4 nanoparticles (Apt-GMNPs). Luminol-functionalized silver nanoparticle-decorated graphene oxide (GO-L-AgNPs) participates in π-π interactions with the unpaired bases of the immobilized aptamer (Apt-GMNPs-GO-L-AgNPs). After the Apt-GMNPs-GO-L-AgNPs were introduced to a gold anodic BPE array, the individual electrodes were subjected to different concentrations of AFM1. Upon the interaction of AFM1 with the aptamers, the GO-L-AgNPs detach from the aptamer; the resulting ECL of luminol and H2O2 at the anodic poles is monitored using a photomultiplier tube (PMT) or smartphone, and the images are analyzed using ImageJ software. This process triggers thionine reduction at the cathodic poles. Under the optimal conditions obtained by a face-centered central composite design (FCCD), the PMT-based detection of the BPE-ECL aptasensor exhibit a linear response over a wide dynamic range from 5 to 150ngmL−1, with a detection limit of 0.01ngmL−1. Additionally, smartphone-based detection shows a linear relationship between the ECL image gray value and the logarithmic concentration of the AFM1 target over a range of 10–200ngmL−1, with a detection limit of 0.05ngmL−1. Furthermore, the BPE-ECL aptasensor was successfully used to detect AFM1 in milk complex media without any serious interferences with reliable reproducibility (average relative standard deviation (RSD = 2.3%)). This smartphone-based detection opens a new horizon for bioanalysis that does not require a trained technician to operate and is a promising technology for point-of-care testing.

Silver nanoparticle-decorated graphene oxide for surface-enhanced Raman scattering detection and optical limiting applications

Silver nanoparticle-decorated graphene oxide was prepared using a simple green chemical reduction method, and its performance being used for surface-enhanced Raman scattering detection and optical limiting was studied. TEM images, photoluminescence quenching effect and the characteristic absorption peaks of GO and silver nanoparticles confirm the successful preparation of GO–Ag nanocomposite. The Raman spectra results show that the vibration fingerprints of RhB and R6G moleculars are detected only on the GO–Ag substrate, revealing good potential of being used as surface-enhanced Raman scattering substrate for detecting organic molecules. Additionally, nonlinear optical absorption of GO–Ag was measured using z-scan technique with a nanosecond laser operating at the wavelength of 532 nm. The z-scan results show that the transmittance of GO–Ag aqueous suspension has a large decline of 90%, and the nonlinear optical absorption onset input fluence of GO–Ag dispersed PVA film is as low as 1.3 J/cm2, indicating that GO–Ag is a good potential optical limiting material for the commonly used high-power 532 nm nanosecond pulsed laser.

A simple non-enzymatic strategy for adenosine triphosphate electrochemical aptasensor using silver nanoparticle-decorated graphene oxide

In this work, a sensitive electrochemical aptasensor for the detection of adenosine triphosphate (ATP) has been introduced. A simple and non-enzymatic signal amplification strategy is utilized using silver nanoparticle-decorated graphene oxide (AgNPs–GO) as a redox probe. The modified electrode surface was characterized by scanning electron microscopy, FTIR and UV–Vis spectroscopy, and electrochemical impedance spectroscopy. GO provides an excellent substrate for the presence of the large number of AgNPs, so the monitored oxidation signal of AgNPs has been amplified. ATP-specific DNA aptamer is split into two fragments (F1 & F2) in order to design a sandwich-type assay. For the construction of the sensor, the surface of a graphite screen-printed electrode is modified with electrodeposited gold nanoparticles followed by self-assembling a monolayer of 3-mercaptopropionic acid on the electrode surface. The first amino-labeled fragment, F1, is immobilized on the modified electrode via carbodiimide chemistry. The synthesized AgNPs–GO interacts with F1 via $$\pi{-}\pi$$ stacking. In the presence of ATP, the second fragment of the aptamer, F2, forms an associated complex with the immobilized F1 and causes AgNPs–GO to leave the surface. Consequently, a remarkable decrease in the oxidation signal of the AgNPs is observed. The percentage of this decrease has been monitored as an analytical signal, which is proportional to ATP concentration, and delivers a linear response over the range of 10.0 (±0.6) to 850 (±5) nM with a detection limit of 5.0 (±0.2) nM.

Ultrafast Synthesis of Silver Nanoparticle Decorated Graphene Oxide by a Rotating Packed Bed Reactor

Graphene-based nanocomposites exhibiting excellent properties have been attracting tremendous interest for their extensive applications. In this work, we present an in situ high-gravitational strategy to synthesize silver/graphene oxide (AGO) nanocomposite in an ultrafast manner and propose a possible mechanism for the formation of silver nanoparticles (Ag-NPs) on graphene oxide (GO) sheets with high coverage density. The size of Ag-NPs can be controlled at ∼5 nm with a narrow size distribution. Transparent conductive films are further fabricated with AGO nanocomposite. The visible transmittance of the Ag/reduced graphene oxide (rGO) film with a sheet resistance of 1.12 kΩ/□ can reach 91%. The graphene-based nanocomposites prepared rapidly by the high-gravity technology, which is easy to realize in large-scale production, may provide extensive applications in electronics, catalysis, optics fields, etc.

Signal-Switchable Electrochemiluminescence System Coupled with Target Recycling Amplification Strategy for Sensitive Mercury Ion and Mucin 1 Assay.

In the present work, we first found that mercury ion (Hg(2+)) has an efficient quenching effect on the electrochemiluminescence (ECL) of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). Since we were inspired by this discovery, an aptamer-based ECL sensor was fabricated based on a Hg(2+) triggered signal switch coupled with an exonuclease I (Exo I)-stimulated target recycling amplification strategy for ultrasensitive determination of Hg(2+) and mucin 1 (MUC1). Concretely, the ECL intensity of ABEI-functionalized silver nanoparticles decorated graphene oxide nanocomposite (GO-AgNPs-ABEI) was initially enhanced by ferrocene labeled ssDNA (Fc-S1) (first signal switch "on" state) in the existence of H2O2. With the aid of aptamer, assistant ssDNA (S2) and full thymine (T) bases ssDNA (S3) modified Au nanoparticles (AuNPs-S2-S3) were immobilized on the sensing surface through the hybridization reaction. Then, via the strong and stable T-Hg(2+)-T interaction, an abundance of Hg(2+) was successfully captured on the AuNPs-S2-S3 and effectively inhibited the ECL reaction of ABEI (signal switch "off" state). Finally, the signal switch "on" state was executed by utilizing MUC1 as an aptamer-specific target to bind aptamer, leading to the large decrease of the captured Hg(2+). To further improve the sensitivity of the aptasensor, Exo I was implemented to digest the binded aptamer, which resulted in the release of MUC1 for achieving target recycling with strong detectable ECL signal even in a low level of MUC1. By integrating the quenching effect of Hg(2+) to reduce the background signal and target recycling for signal amplification, this proposed ECL aptasensor was successfully used to detect Hg(2+) and MUC1 sensitively with a wide linear response.

An ultrasensitive sandwich type electrochemiluminescence immunosensor for triiodothyronine detection using silver nanoparticle-decorated graphene oxide as a nanocarrier.

An ultrasensitive electrochemiluminescence (ECL) immunosensor was constructed to detect 3,3',5-triiodothyronine (T3). The system employed T3-conjugated, silver nanoparticle-decorated carboxylic graphene oxide (Ag@fGO-T3) as a carrier and anti-T3 antibody-tris(2,2'-bipyridyl) ruthenium(II) (Ru(bpy)3(2+)) as a probe. The Ag@fGO-T3 and Ru(bpy)3(2+) complex could be mobilized rapidly to the anode in the reaction chamber through electrophoresis. The fGO is reduced electrochemically at the electrode, and the electrons could transfer from an anode to the Ru(bpy)3(2+). The complex is excited at the electrode and an ECL signal is produced upon reacting with tripropylamine (TPrA). Because of its large surface area and excellent conductivity, Ag@fGO could enhance ECL signal significantly in the system. Quantitative measurement of T3 could be achieved in the range from 0.1 pg/mL to 0.8 ng/mL with a detection limit of 0.05 pg/mL. In addition, the novel immunosensor showed good specificity in the presence of serum, indicating its high potential in clinical use.

Preparation, characterization, and antibacterial activity of silver nanoparticle-decorated graphene oxide nanocomposite.

In this work, we report a facile and green approach to prepare a uniform silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite (GO-Ag). The nanocomposite was fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, and X-ray photoelectron spectroscopy (XPS), which demonstrated that AgNPs with a diameter of approximately 22 nm were uniformly and compactly deposited on GO. To investigate the silver ion release behaviors, HEPES buffers with different pH (5.5, 7, and 8.5) were selected and the mechanism of release actions was discussed in detail. The cytotoxicity of GO-Ag nanocomposite was also studied using HEK 293 cells. GO-Ag nanocomposite displayed good cytocompatibility. Furthermore, the antibacterial properties of GO-Ag nanocomposite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 by both the plate count method and disk diffusion method. The nanocomposite showed excellent antibacterial activity. These results demonstrated that GO-Ag nanocomposite, as a kind of antibacterial material, had a great promise for application in a wide range of biomedical applications.

Removal of Pb(II) using silver nanoparticles deposited graphene oxide: equilibrium and kinetic studies

Silver nanoparticles-decorated graphene oxide (Ag-GO) composites as advanced metal ion adsorbents have been synthesized. The silver nanoparticles (Ag-NPs) were homogeneously deposited onto graphene oxide (GO) surface by an optimal method, in which N,N-dimethylformamide as a co-dispersant is added to an aqueous suspension of GO and AgNO3. The Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy indicates that GO and Ag-GO are fully exfoliated. The synthesized Ag-GO NPs were used for removal of Pb(II) metal ions. The experiments showed that the removal of metal ions followed a pseudo-second-order kinetic model and equilibrium adsorption studies confirmed that the Langmuir model provided a better fit than others as revealed by high correlation coefficients and low Chi-square values. These Ag-GO NPs can be successfully used for the separation of Pb(II) from aqueous solutions.

Facile synthesis of silver nanoparticle-decorated graphene oxide nanocomposites and their application for electrochemical sensing

TWEEN 80 was employed as the reducing agent, stabilizer and modifier in the synthesis of nanoparticle–graphene oxide nanocomposites.

Amperometric detection of Sudan I in red chili powder samples using Ag nanoparticles decorated graphene oxide modified glassy carbon electrode

A simple and sensitive electrochemical method was developed to determine the concentration of Sudan I in chili powder based on silver nanoparticles decorated graphene oxide modified glassy carbon electrode (AgNPs@GO/GCE). The voltammetry behaviour of Sudan I on modified GCE was investigated in phosphate buffer medium (PBS) with various pH ranges and the electron transfer properties were studied. It is found that the AgNPs@GO/GCE can catalyse the reduction of azo group, NN followed by electrochemical oxidation of -OH group present in Sudan I dye molecule. Quantitative detection of Sudan I present in food products was carried out by amperometry method in which reduction potential was fixed at −0.77V vs. Ag/AgCl. The amperometry method showed an excellent performance with a sensitivity of 6.83μAmM−1 and a detection limit of 11.4×10−7ML−1. A linear calibration graph was constructed in the ranging 3.90×10−6 to 3.19×10−5ML−1. The method was successfully applied for the determination of Sudan I in red chili powder samples.