A Bifunctional Nanosilver-Reduced Graphene Oxide Nanocomposite for Label-Free Electrochemical Immunosensing

Abstract

A bi-functional material based on silver nanoparticles (AgNPs)-reduced graphene oxide (rGO) composite for both electrode modification and signal generation is successfully synthesized for use in the construction of a label-free electrochemical immunosensor. An AgNPs/rGO nanocomposite is prepared by a one-pot wet chemical process. The AgNPs/rGO composite dispersion is simply cast on a screen-printed carbon electrode (SPCE) to fabricate the electrochemical immunosensor. It possesses a sufficient conductivity/electroreactivity and improves the electrode reactivity of SPCE. Moreover, the material can generate an analytical response due to the formation of immunocomplexes for detection of human immunoglobulin G (IgG), a model biomarker. Based on electrochemical stripping of AgNPs, the material reveals signal amplification without external redox molecules/probes. Under optimized conditions, the square wave voltammetric peak current is responded to the logarithm of IgG concentration in two wide linear ranges from 1 to 50 pg.ml−1 and 0.05 to 50 ng.ml−1, and the limit of detection (LOD) is estimated to be 0.86 pg.ml−1. The proposed immunosensor displays satisfactory sensitivity and selectivity. Importantly, detection of IgG in human serum using the immunosensor shows satisfactory accuracy, suggesting that the immunosensor possesses a huge potential for further development in clinical diagnosis.

Ionic Liquid-Functionalized ZrO2/Reduced Graphene Oxide Nanocomposites for Carcinoembryonic Antigen Electrochemical Detection

“…However, a further increase in pH from 7.4 to 9 gradually diminishes the peak current. Since an acidic and basic pH medium causes denaturing of antibodies immobilized at the electrode surface, such denatured antibodies result in a lower current response. , Hence, the PBS of pH 7.4 is considered to be a highly suitable redox electrolyte. In addition, the pH of 7.4 corresponds to the pH of blood; therefore, the PBS of pH 7.4 was chosen for immunosensing purposes.…”

Recent advances on the development of graphene‐based field‐effect transistors, electrochemical biosensors and electrochemiluminescence biosensors

“… (a) Scheme for preparation process of the typical sandwich‐type electrochemical immunosensors, in which N atom‐doped graphene (NGR) functionalized with hollow porous Pt‐skin Ag−Pt alloy (HP−Ag/Pt/NGR) and Au nanoparticles modified polypyrrole/poly (3,4‐ethylenedioxythiophene) nanotubes were fabricated as the signal amplifier and the substrate, respectively [88]. (b) Scheme for the fabrication of AgNP/rGO‐based label‐free electrochemical immunosensor [100]. (c) Schematic diagram of the preparation of zeolitic imidazolate frameworks and gold nanoparticle modified reduced graphene oxide (Au@ZIF‐8@rGO)‐based electrochemical immunosensor and the detection of glial fibrillary acidic protein (GFAP) [99a].…”

Bio-Tailored Sensing at the Nanoscale: Biochemical Aspects and Applications

“…When approaching the use of more advanced nanomaterials in building efficient biosensors, proteins, enzymes and antibodies are largely considered as their intrinsic biochemical and structural features make them ideal candidates to assemble hybrid composites while keeping useful properties such as enzymatic activities, self-assembly behavior and biorecognition. As a first example, Chanarsa et al [ 69 ] reported a AgNPs-reduced GO composite as a component of an electrochemical immunosensor able to detect the immunoglobulin G as a model biomarker in blood serum ( Figure 7 ). In their study, the authors realized an AgNPs-reduced GO composite from a heat-assisted wet chemical reduction that can be easily deposited onto a screen-printed carbon electrode and used as support for adsorption of unfunctionalized antibodies specific for immunoglobulin G (IgG).…”

“… Electrochemical immunosensor for immunoglobulin G in blood serum. Screen-printed carbon electrodes are coated with AgNPs-reduced GO composites linked to antibodies specific for immunoglobulin G. Image adapted from [ 69 ] with permission of Frontiers, 2021. …”