Direct Enzyme-Amplified Electrical Recognition of a 30-Base Model Oligonucleotide

摘要

Electrochemical sensors, recognizing hybridization of DNA strands based on electrogenerated chemiluminescence and cyclic voltammetry of intercalated ruthenium and cobalt complexes and organic dyes and of redox functions covalently bound to single DNAstrands have been reported. Also a direct- enzyme-amplified amperometric affinity assay for the avidin-biotin conjugate has been described. In this system, bonding of biotinylated horseradish peroxidase to avidin covalently attached to an electron-conducting redox hydrogel resulted in the "Wiring" of the enzyme, i.e. its electrical connection to the electrode. Such connection produced ail H_2O_2 electroreduction current proportional to the1 number of conjugates. Here we show that the hybridization of amodel oKgonudeotide can be directly measured as an electrical current The current flows as a result of continuous electroreduction of H_2O_2, electrocatalyzed by me horseradish peroxidase (HRP) label of an oligonucleotide strand when the complementary strand is covalently bound to a hydrogel mat electrically "wires" the HRP (Figure 1). In such a hydrogel, electrons diffuse Via self-exchange of electrons between colliding segments of the redox polymer network, which become mobile when hydrated.