Electrochemical Biofunctionalization of Highly Oriented Pyrolytic Graphite for Immunosensor Applications

摘要

The present research demonstrates a procedure for surface modification of Highly Oriented Pyrolytic Graphite (HOPG) electrodes intended for use as immunosensors. The HOPG surface is linked to the molecule 8-hydroxydeoxyguanosine (8-OHdG), an oxidative stress biomarker for DNA damage, though the aniline mediator covalently bonded to electrode and biomarker. An electrochemical procedure to graft the mediator is described and the presence of biomarker at surface is demonstrated by using a fluorescence-labeled immune-reagent. An electrochemical functionalization process has been employed for attachment of functional aminie (NH2) linking groups to graphitic surfaces, which consists of two stages: (i) a reaction with a diazonium salt to covalently bond nitrobenzene groups to the surface and (ii) electrochemical reduction of the nitro group (–NO2) to an amine group (–NH2). The shape of the CV curve indicates that the redox reactions are taking place at the HOPG electrode surface. The amine group can subsequently be used to covalently link to an antibody biorecptor. The presence of 8-OHdG, indicative of DNA damage, has been linked to increased cancer risk. Detection of this oxidative stress biomarker is an important tool for the early diagnosis of disease. [DOI: 10.1380/ejssnt.2016.193]