Scheme 1. E-DNA Sensors with Oligodeoxythymidylate [(dT)_n] DNA Probes Exhibit a Decrease in the Current Signal When a Target g32 Protein Is Bound.

Oligo(dT) E-DNA sensors comprise a sensing electrode modified with single-stranded, unstructured oligo(dT), [(dT)_n], DNA strands of various lengths (7, 14, and 21 nucleotides) modified at their distal ends with a redox-active methylene blue. Protein binding to the oligo(dT) E-DNA sensor causes a change in the flexibility of the (dT)_n probe; thus, the efficiency with which electrons can be transferred results in a decrease in the measured current (signal-off).