Mimic Peroxidase- and Bi₂S₃ Nanorod-Based Photoelectrochemical Biosensor for Signal-On Detection of Polynucleotide Kinase

Abstract

We demonstrate for the first time the development of a mimic peroxidase- and bismuth sulfide (Bi₂S₃) nanorod-based photoelectrochemical (PEC) biosensor for signal-on detection of polynucleotide kinase (PNK) on the basis of manganese-based mimic enzyme (MnME) catalytic precipitation. We use the hybrid film which consists of Bi₂S₃ nanorods and Au nanoparticles (AuNPs) as the immobilization matrix of capture probe. The capture probe on the modified electrode can specifically hybridize with the MnME@AuNPs-labeled signal probe to form the double-stranded DNA (dsDNA), generating a PEC biosensor. In the absence of PNK, MnME may stimulate the mimic enzyme catalytic precipitation onto the electrode surface, blocking the interfacial electron transfer and eventually leading to a low PEC signal. While in the presence of PNK, the dsDNA is phosphorylated and subsequently cleaved by lambda exonuclease to release the MnME@AuNPs conjugates from the electrode, leading to the decrease of catalytic precipitation on the surface of electrode and consequently the production of a high PEC signal. Notably, the MnME can be easily synthesized and possesses higher catalytic activity than the manganese-based mimic enzyme. This signal-on PEC biosensor exhibits high sensitivity with a detection limit of 1.27 × 10^-5 U mL^-1 and an extrembly large dynamic range of 5 orders of magnitude. Moreover, it can be applied for the screening of PNK inhibitors and accurate quantification of PNK activity in cancer cell extracts.