Sensitive photoelectrochemical determination of T4 polynucleotide kinase using AuNPs/SnS2/ZnIn2S4 photoactive material and enzymatic reaction-induced DNA structure switch strategy

We report here Au nanoparticles (AuNPs)/SnS2/ZnIn2S4 as a high-performance active material for sensitive photoelectrochemical (PEC) determination of T4 polynucleotide kinase (T4 PNK) using an enzymatic reaction induced DNA structure switch strategy. To construct the PEC biosensor, a double-stranded DNA probe consisting of a CdS quantum dots (QDs)-labeled single-stranded DNA (sDNA) and its complementary DNA (cDNA) is immobilized on the AuNPs/SnS2/ZnIn2S4 photoactive material. T4 PNK can catalyze the phosphorylation of 5'-OH-terminated sDNA in the double-stranded DNA probe when ATP is present, and lambda-exonuclease can catalyze the degradation of the phosphorylated sDNA into small fragments. Then the cDNA forms a hairpin structure so that CdS QDs and AuNPs are in close contact, which can induce exciton-plasma interactions between CdS QDs and AuNPs. The exciton-plasma interactions significantly boost the photocurrent, enabling the signal on PEC determination of T4 PNK in the range of 10(-4) 1 U mL(-1) with a detection limit of 6 x 10(-5) U mL(-1). The PEC biosensor can also be used to screen enzyme inhibitors.

Automated summary

In this study, we developed a photoelectrochemical (PEC) biosensor using Au nanoparticles (AuNPs)/SnS2/ZnIn2S4 as the active material, for sensitive detection of T4 polynucleotide kinase (T4 PNK) based on an enzymatic reaction induced DNA structure switch strategy. The PEC biosensor exhibited high performance with a wide detection range and low detection limit, and can also be used for screening enzyme inhibitors.