Electrochemically Exfoliated Graphene Oxide for Simple Fabrication of Cocaine Aptasensors

Abstract

Transducers made from graphene-type materials are widely used in sensing applications. However, utilization of graphene oxide obtained from electrochemical exfoliation of graphite (EGO) has remained relatively unexplored. In this study, electrochemical cocaine aptasensors based on large-size EGO flakes were investigated. In particular, the influence of the following parameters on the sensor performance was examined: (i) aptamer's terminal group (−NH 2 vs −OH), (ii) functionalization of EGO with the aptamer via physical adsorption and covalent immobilization, and (iii) intrinsic electrochemical properties of EGO such as the electrochemical surface area (ESA) and standard rate constant of electron transfer (k 0 ). The results demonstrate that EGO-based electrochemical aptasensors fabricated by physical adsorption with an NH 2 -modified aptamer have very good reproducibility, shelflife stability, and high sensitivity for detecting cocaine with a detection limit of 50 nM. Their performance is comparable to that of the aptasensors prepared using the covalent immobilization. Additionally, it is shown that EGO materials with high ESA and k 0 can enhance the sensing performance. The fast (less than 10 min) and strong adsorption of the NH 2 -modified cocaine aptamer on the surface of large EGO flakes makes the fabrication of the sensing platform simple and rapid. This simple approach has the potential to simplify the fabrication of sensors.

Aptamer-Functionalized Hydrogel Biosensor Targeting Trace Antibiotics via UV Detection

“…Graphene oxide (GO) was prepared using graphite powder according to the Hummers method. , 2.0 g of graphite powder and 2.0 g of sodium nitrate were mixed in a beaker, and 92.0 mL of concentrated sulfuric acid (98.0%) was slowly added dropwise into it under ice bath conditions with continuous stirring. After stirring for 4 h,12.0 g of KMnO 4 was added three times under the same conditions.…”

Molecularly Imprinted Polymer Biosensor Based on Nitrogen-Doped Electrochemically Exfoliated Graphene/Ti3 CNTX MXene Nanocomposite for Metabolites Detection

“…The two-dimensional structure of MXene, distinguished by its superior metal conductivity, large specific surface area, diverse compositions, and hydrophilicity, positions it as a promising material for developing biosensors in various applications within healthcare, environmental monitoring, and diagnostics. , However, challenges such as limited interlayer spacing, self-restacking, and aggregation of MXene hinder the full utilization of its superior surface metal properties. To address this limitation, the introduction of graphene between MXene layers acts as a “buffer” and spacer, preventing undesired stacking of MXene nanosheets and enhancing their electrochemical properties. − Electrochemically exfoliated graphene (EEG), with its high electrical conductivity, tunable electrical properties, large surface area, biocompatibility, low cost, and excellent repeatability, − could be an emerging nanostructure for modifying MXene nanosheets in biosensors.…”