Highly sensitive electrochemical lead ion sensor harnessing peptide probe molecules on porous gold electrodes

Lead ion is one of the most hazardous and ubiquitous heavy metal pollutants and poses an increasing threat to the environment and human health. This necessitates rapid and selective detection and/or removal of lead ions from various soil and water resources. Recently, we identified several Pb2+ binding peptides via phage display technique coupled with chromatographic biopanning (Nian et al., 2010) where a heptapeptide (TNTLSNN) capable of recognizing Pb2+ with high affinity and specificity evolved. In the present study, an electrochemical sensor harnessing this Pb2+ affinity peptide as a probe on a porous gold electrode was developed. The three dimensional porous gold electrode was obtained from electrochemical deposition using the dynamic hydrogen bubble template method. A thin layer of poly(thiophene acetic acid) (PTAA) was coated on the porous gold surface. The Pb2+ recognizing peptide was immobilized via amide linkage on the PTAA. The developed biosensor was demonstrated to be fast, selective and reproducible in Pb2+ detection, exhibiting Pb2+-specific peak current values around −0.15 V in a broad concentration range (1−1×107 nM) in 10 min despite the repeated use after regeneration.