Carbon Nanostructures for Tagging in Electrochemical Biosensing: A Review

Abstract

Growing demand for developing ultrasensitive electrochemical bioassays has led to the design of numerous signal amplification strategies. In this context, carbon-based nanomaterials have been demonstrated to be excellent tags for greatly amplifying the transduction of recognition events and simplifying the protocols used in electrochemical biosensing. This relevant role is due to the carbon-nanomaterials' large surface area, excellent biological compatibility and ease functionalization and, in some cases, intrinsic electrochemistry. These carbon-based nanomaterials involve well-known carbon nanotubes (CNTs) and graphene as well as the more recent use of other carbon nanoforms. This paper briefly discusses the advantages of using carbon nanostructures and their hybrid nanocomposites for amplification through tagging in electrochemical biosensing platforms and provides an updated overview of some selected examples making use of labels involving carbon nanomaterials, acting both as carriers for signal elements and as electrochemical tracers, applied to the electrochemical biosensing of relevant (bio)markers.

Carbon Dots and Graphene Quantum Dots in Electrochemical Biosensing

“…It is well known that nanostructuration of working electrodes with nanosized carbon modifiers provides attractive new features, such as easy physical adsorption onto electrodes through van der Waals forces; fast electron transfer kinetics due to their extremely high conductivity along particular directions; high surface area, which enhances biomolecules’ adsorption; highly selective and tunable catalysts due to their unique electronic or plasmonic structure; and tunable surface chemistry towards the direction of the assembly for particular capture probe or analyte species [1]. In addition, their excellent biological compatibility, ease of preparation, and organic functionalization make carbon-based nanomaterials excellent carriers for loading numerous signal elements, such as enzymes, oligonucleotides, antibodies, redox molecules, and inorganic nanomaterials, to greatly amplify the transduction signals of recognition events in electrochemical bioassays [2].…”

Influence of Graphene Oxide Concentration when Fabricating an Electrochemical Biosensor for DNA Detection

“…In contrast to classic approaches for DNA sensors, with target DNA labeled by an enzyme or a fluorophore, electrochemical impedance spectroscopy (EIS) offers label-free detection in addition to the advantages of relative simplicity, low cost, ease of miniaturization, and portability [13,14]. Other electrochemical detection methods include the common amperometric or voltammetric techniques, such as cyclic voltammetry (CV), differential pulse voltammetry and square-wave voltammetry, which involve the measurement of a current related to the analyte concentration under controlled potential conditions [15,16]. EIS is a technique of choice because it can detect significant changes in the signal in a low target concentration range [14,17] and is non-destructive, due to the low amplitude voltage perturbation that is much smaller than that used in amperometric testing [18][19][20][21].…”

Enzyme-Based Biosensors: Tackling Electron Transfer Issues

“…Among all kinds of electrode materials, metal nanoparticles and carbon-based nanomaterials play an important role in the electrode modification, because of their high surface area-to-volume ratios and high surface energy, which facilitate immobilization of enzymes, allowing them to act as electron conducting pathways between the prosthetic groups of the enzymes and electrode surfaces. Due to the high research activity in this area, the advances in this research direction have been extensively reviewed [ 183 , 184 , 185 ].…”