Electrochemical biosensors based on divinyl sulfone conjugation of DNA to graphene oxide electrodes

Abstract

We immobilized unmodified, single-stranded (ss) DNA oligonucleotides on graphene oxide (GO) using divinyl sulfone (DVS). This is a new and useful method for generating DNA biosensors that avoids the need for modified oligonucleotides with synthetic attachment chemistry. This technique yields time and cost savings. The synthesis of unmodified oligonucleotides is simpler, quicker, and less expensive than modified DNA. DVS has two reactive vinyl groups that can link labile functional groups on the GO surface to the DNA. We show that the DNA nucleobase is covalently bonded to DVS. This opens the use of ubiquitous glassy carbon electrodes (GCE) for fabricating DNA biosensors by drop-casting GO. Reverse-complimentary DNA was detected using multiple electrochemical methods. The results show that DNA can be successfully conjugated to conductive carbon for electrochemical sensors. This is simpler than other methods for functionalizing carbon electrodes. This has clear advantages over gold electrodes in terms of its electrochemical potential window.