Reagent-less electrogenerated chemiluminescence peptide-based biosensor for the determination of prostate-specific antigen

A novel electrogenerated chemiluminescence peptide-based (ECL-PB) biosensor for highly sensitive and selective determination of prostate-specific antigen (PSA) was developed. A helix peptide (CHSSKLQK) was served as a molecular recognition element and ruthenium bis(2,2′-bipyridine) (2,2′-bipyridine-4,4′-dicarboxylic acid)-N-hydroxysuccinimide ester (Ru(bpy)2(dcbpy)NHS) was used as an ECL label. The helix peptide was labeled with the ECL label at NH2-containing lysine and utilized as ECL probe (Ru-peptide). The ECL-PB biosensor was fabricated by immobilizing the ECL probe onto a gold electrode surface via self-assembling technique through a thiol-containing cysteine at the end of the peptide. The principle of ECL measurement is based on the specific proteolytic cleavage event of Ru-peptide on the gold electrode surface in the presence of PSA, resulting in a decrease of ECL signal. The decreased ECL intensity was directly linear to the concentration of PSA in the range from 1.0×10−10 g/mL to 8.0×10−9 g/mL with a detection limit of 3.8×10−11 g/mL. This work demonstrates that the direct transduction of peptide cleavage events into an ECL signal provides a simple and sensitive method for detecting target protein.