Thiophene-Conjugated Ligand Probe for Nonenzymatic Turn-On Electrochemical Protein Detection

A new
type of turn-on electrochemical protein detection is developed
using an electropolymerizable molecular probe. To detect trypsin,
a benzamidine ligand is conjugated with a thiophene moiety. Encapsulation
of the probe in the trypsin pocket prevents electropolymerization,
leading to efficient electron transfer from the electrolyte to the
electrode. In contrast, unbound probes can become electropolymerized,
yielding a polythiophene layer on the electrode. The polythiophene
formed this way suppressed electron transfer. The detection limit
of trypsin using this electrochemical strategy is 50 nM. The method
is shown to be useful for nonenzymatic turn-on electrochemical detection.