Preparation of a novel iron cryptate as an electrochemical probe for biosensing

Abstract

A novel dicarboxyl-functionalized iron cryptate with a 2,2-pyridine unit has been synthesized, which displays outstanding electrochemical properties in water as a potential biosensing probe. Taking the silver ion (Ag+) as an example, we report a novel Ag+ assay by recording the electrochemical signals of Fe cryptate. In summary, a hairpin-structured DNA probe is designed and modified with the synthesized Fe cryptate. In the absence of Ag+, this is absorbed on the surface of a reduced graphene oxide modified electrode and a significant electrochemical response is obtained. In the presence of Ag+, cytosine–cytosine mismatches in the DNA probe recognize target ions and it is transformed into a conformation which cannot resist digestion by exonuclease III. As a result, Fe cryptate is released and Ag+ is recycled for continuous DNA digestion. By analyzing the reduced electrochemical signals of Fe cryptate, it is possible to quantify the target ions. Keywords: Biosensor, DNA conformation, Silver ions, Exonuclease, Cryptate