Photocatalytic electrochemical sensor based on three-dimensional graphene nanocomposites for the ultrasensitive detection of CYFRA21-1 gene

摘要

A photocatalytic electrochemical DNA genosensor based on polyaniline nanofibers and three-dimensional reduced graphene oxide (3D-rGO) modified glassy carbon electrode has been fabricated. It can ultrasensitively detect non-small cell lung cancer gene CYFRA21-1 through photocatalytic reaction. Ethidium bromide is adopted to embed into double stranded DNA (dsDNA) for generating singlet oxygen under green LED irradiation, thereby efficiently cleaving the dsDNA. As a result, the peak currents of [Fe(CN)6]3-/4- increase obviously, due to less blocking of nanocomposites modified electrode and weaker electrostatic repulsion after dsDNA fragmentation. The theoretical LOD is 76.2 aM (3 sigma) and the peak current is linear with the increasing concentration of complementary DNA target from 0.1 fM to 0.1 mu M. This genosensor also possesses good specificity, acceptable stability and reproducibility toward CYFRA21-1, and was successfully applied for the detection of CYFRA21-1 in real serum samples.