Amplified Voltammetric Strategy for the Detection of Proteases Using Dopamine-Modified Gold Nanoparticles

In this work, we reported a label-free and amplified electrochemical strategy for the detection of proteases using dopamine (DA)-modified gold nanoparticles (DA-AuNPs) as redox probes. To demonstrate the feasibility and sensitivity, thrombin was tested as a model analyte. Specifically, peptide with a sequence of CSGFPRGRY was immobilized onto the gold electrode. Monophenol of tyrosine residue in the peptide was catalytically oxidized by tyrosinase to catechol. The resultant catechol was derivatized with 1,4-phenyldiboronic acid (PDBA) for the attachment of electrochemically active DA-AuNPs through the formation of tight covalent bond between boronic acid and catechol group, which facilities the amplified voltammetric detection. However, the cleavage of peptide by thrombin induced the loss of tyrosine residue, resulting in the decrease in the amount of catechol group and DA-AuNPs on electrode. The magnitude of the decrease in the peak current is related to the concentration and activity of thrombin.