Electrochemical aptasensor for lysozyme based on a gold electrode modified with a nanocomposite consisting of reduced graphene oxide, cuprous oxide, and plasma-polymerized propargylamine

Abstract

This article describes an aptasensor for lysozyme that is based on a gold electrode modified with an aptamer-wrapped composite consisting of three-dimensional reduced graphene oxide, cuprous oxide, and plasma-polymerized propargylamine (Cu2O@rGO@PpPG) as the sensing layer. The nanocomposite consisting of Cu2O@rGO was synthesized by simultaneously reducing GO and Cu(II) ions with glucose and then modified by plasma-enhanced chemical vapor deposition using propargylamine as the monomer gas. The resulting amine-rich nanofilms of Cu2O@rGO@PpPG nanocomposite were deposited on a gold electrode. Differential pulse voltammetry and electrochemical impedance spectroscopy show these layers to exhibit a good amperometric response and variation of the charge transfer resistance to lysozyme after aptamer strands had been immobilized on the films via electrostatic interaction between the negatively charged phosphate groups of the aptamer and the positively charged amino groups on the electrode. The sensor, when operated at 0.22 V (vs. Ag/AgCl), can detect lysozyme in the 0.1 nM to 200 nM concentration range with a 0.06 nM limit of detection. In addition, the sensor displays excellent selectivity and repeatability. In our perception, this strategy for preparing aptasensors holds a great potential with respect to the use of plasma-modified nanocomposites in clinical analysis.