Highly sensitive photoelectrochemical and electrochemical dual-mode biosensing of polynucleotide kinase based on multifunctional BiOBr0.8I0.2 /CuSCN composite and biocatalytic precipitation

Polynucleotide kinase (PNK) plays an important role in maintaining genome integrity and is directly related to many severe human diseases, so its detection is of great significance. To accurately and reliably detect PNK, a photoelectrochemical (PEC) - electrochemical (EC) dual-mode biosensor is created based on BiOBr0.8I0.2/CuSCN multifunctional nanocomposite. In this protocol, the nanocomposite loaded Au nanoparticles (AuNPs) are used to immobilize capture probe P1, while the signal probe P2 is labeled by glucose oxidase modified AuNPs (GOx@AuNPs-P2). They precisely hybridize to produce a double-stranded DNA (ds-DNA)-contained composite at the ITO electrode, which can be phosphorylated in the presence of PNK before being cleaved selectively by λ-exonuclease and leaving the electrode surface. The uncut ds-DNA with GOx@AuNPs-P2 catalyzes glucose to generate H2O2, and under the catalysis of peroxidase-like BiOBr0.8I0.2/CuSCN, 4-chlorohexadione precipitation is produced, which amplifies PEC and EC signals. Owing to the coordination effect of different elements, including enzyme and aptamers, the proposed PEC-EC dual-mode platform displays high sensitivity and selectivity. Furthermore, the sensor shows high repeatability and stability. Further experiments indicate it has excellent application potential in the detection and inhibitor screening of PNK.