Reduced Graphene Oxide Gold Nanoparticles Research Articles

Preparation of zinc oxide nanoparticle–reduced graphene oxide–gold nanoparticle hybrids for detection of NO2

A novel NO2 gas sensor bas been fabricated using ZnO–rGO–Au hybrids as sensing materials, which exhibit excellent sensing performances operated at 80 °C.

Biogenic gold nanoparticles-reduced graphene oxide nanohybrid: synthesis, characterization and application in chemical and biological reduction of nitroaromatics

The biogenic AuNPs/rGO can participate in and accelerate electron transfer, and catalyze both chemical and biological reduction of nitroaromatics efficiently.

An electrochemical DNA biosensor for the detection of Mycobacterium tuberculosis, based on signal amplification of graphene and a gold nanoparticle-polyaniline nanocomposite.

Due to its low growth rate and its fastidious nature, Mycobacterium tuberculosis is difficult to identify. Its rapid and sensitive detection is, however, critical for the control of tuberculosis. Molecular biology, and more recently electrochemical technology, have been exploited for the detection of this pathogen. In the present study, a novel DNA biosensor was developed for the highly sensitive detection of the specific DNA insertion sequence IS6110 of M. tuberculosis, using reduced graphene oxide-gold nanoparticles (rGO-AuNPs) as a sensing platform and gold nanoparticles-polyaniline (Au-PANI) as a tracer label for amplification. Reduced graphene oxide, which has a large surface area, provided a biocompatible matrix. Gold nanoparticles were electrodeposited on the surface of the rGO modified electrode, which not only increased immobilisation of the capture probe but also promoted electronic transfer. The Au-PANI nanocomposite exhibited good biocompatibility and excellent electrochemical activity. It was therefore used as a tracer label for electrochemical detection, which provided a simple preparation process for a signal-on DNA biosensor. With the excellent electroactivity of the Au-PANI nanocomposite, the resulting DNA biosensor exhibited high sensitivity for the detection of M. tuberculosis over a broad linear range, between 1.0 × 10(-15) and 1.0 × 10(-9) M. The DNA biosensor showed good stability and high specificity and provides a new strategy for clinical M. tuberculosis diagnostics and probably also for pathogenic bacteria in general.

Investigation of the optimal weight contents of reduced graphene oxide–gold nanoparticles composites and theirs application in electrochemical biosensors

Graphene, as a single-atom-thick carbon material, is considered an ideal platform for designing composite nanomaterials for high-performance electrochemical or electrocatalytic devices. Reduced graphene oxide–gold nanoparticles composites were prepared by depositing gold nanoparticles (AuNPs) on the surface of reduced graphene oxide (RGO) with different RGO-to-AuNPs weight ratios. The resulting composite materials were characterized morphologically and optically by scanning electron microscopy (SEM) and UV–visible absorption spectroscopy. Cyclic voltammetry and amperometric measurements were employed to investigate the electrocatalytic effect of different composites toward the reduction of hydrogen peroxide. Experimental results demonstrated that RGO–AuNPs composites displayed high stability and catalytic effect for the analysis of hydrogen peroxide, demonstrating the possible synergistic effects of the RGO–AuNPs composite materials. Additionally, direct electron transfer of glucose oxidase (GOD) was achieved after codeposition of GOD and chitosan (CHIT). The glassy carbon electrode modified with RGO–AuNPs/CHIT–GOD material exhibited an excellent catalytic effect for glucose detection with a sensitivity of 34mAM−1cm−2 at a detection potential of −0.3V vs. Ag|AgCl reference.

Porous-layered stack of functionalized AuNP–rGO (gold nanoparticles–reduced graphene oxide) nanosheets as a sensing material for the micro-gravimetric detection of chemical vapor

With oleylamine as a solvent and reducing agent, Au nanoparticles (AuNPs) are grown in situ on graphene oxide (GO) sheets. Thereafter, a porous-layered stack of AuNPs–GO nanosheets is formed by a gas-phase chemical reduction step. After the AuNPs are modified with 11-mercaptoundecanoic acid (11-MUA) to graft –COOH sensing groups to the amine, the functionalized AuNPs–rGO porous-layer stacked nanosheets are loaded onto a gravimetric resonant microcantilever for use as a mass sensing material. The rGO sheets serve as multi-layer nano-shelves to support and carry the functionalized AuNPs for gas adsorbing/sensing, while the AuNPs serve as nano-spacers between the rGO sheets to provide a high specific surface area for gas molecules accessing the material. The cantilever sensor experimentally exhibits a very rapid response to ppm-level trimethylamine (TMA) vapor, which is attributed to the novel sensing material. Compared with the hydrophilic AuNP–GO, the highly hydrophobic AuNP–rGO shows a much improved suppression to the noise from changes in environmental humidity. Featuring a rapid response, high sensitivity and good resistance to interference from environmental moisture, the novel sensing nanomaterial is promising in various chemical vapor detection applications.

One-pot green synthesis, characterizations, and biosensor application of self-assembled reduced graphene oxide-gold nanoparticle hybrid membranes.

We report here a facile one-pot green synthesis method to prepare a self-assembled membrane of reduced graphene oxide-gold nanoparticle (RGO-AuNP) nanohybrids at a liquid-air interface. The obtained sandwich-like multilayer RGO-AuNP hybrid membranes were characterized by atomic force microscopy, scanning electron microscopy, transmission electron microscopy, UV-vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy, and the obtained results prove that GO and chloroauric acid (HAuCl4) were synchronously reduced by glucose successfully. In addition, the experimental data indicate that the self-assembly and formation of RGO-AuNP hybrid membranes are mainly governed by the Brownian motion and electrostatic interaction between RGO and AuNPs, and the encapsulation of AuNPs in the hybrid membrane can be easily adjusted by changing the concentration of HAuCl4. The created functional semi-transparent RGO-AuNP hybrid membranes are very stable in various organic and inorganic solvents, and can be used to fabricate a novel nonenzymatic amperometric biosensor of hydrogen peroxide (H2O2). The fabricated H2O2 biosensor reveals a wide linear range from 0.25 to 22.5 mM, low detection limit of 6.2 μM (S/N = 3), high selectivity, and long-term stability. It is expected that this one-pot green method for fabricating sandwich-like multilayer hybrid functional membranes has broad applications in biosensing, catalysis, and energy storage.

A new green, ascorbic acid-assisted method for versatile synthesis of Au–graphene hybrids as efficient surface-enhanced Raman scattering platforms

A new green method for the synthesis of reduced graphene oxide–gold nanoparticle (rGO–AuNP) hybrids in aqueous solution that exploits the ability of ascorbic acid (AA) to operate as an effective dual agent for both graphene oxide (GO) and gold ion reduction is reported. Through careful investigation of the production of rGO–AuNP hybrids stabilized with polyvinylpyrrolidone (PVP), several versatile routes were devised with the aim of controlling the size, shape and distribution of AuNPs anchored onto the graphene sheets as well as the GO reduction. Particularly, when rGO is used as a platform for Au ion nucleation, a relative sparse distribution of AuNPs of size ranging from 20 nm to 50 nm is noticed. In contrast, when gold ions are added to the solution prior to any GO reduction, the density of large AuNPs is rather low relative to the uniformly packed small sized AuNPs (3–12 nm). The progress of GO reduction is explained by considering the contribution of the catalytic activity of AuNPs, besides the reducing activity of AA. Finally, a plausible mechanism for the nucleation and distribution of AuNPs onto the graphenic surface is assumed, highlighting the significance of oxygen moieties. The green method developed here is promising for the fabrication of gold–graphene nanocomposites with tunable surface “decoration”, suitable for surface-enhanced Raman spectroscopy (SERS).