A simple label-free electrochemical method for the detection of polynucleotide kinase activity by a peroxidase mimic: TiO2 nanotube array

Abstract

Phosphorylation of DNA by polynucleotide kinase (PNK) plays an important role in a variety of cellular processes, such as nucleic acid metabolism and DNA damage repair. Strategies for a simple and effective PNK assay are in urgent need. Here we report the development of a simple label-free electrochemical method for a PNK assay based on the mimic peroxidase character of a prepared TiO₂ nanotube array (NTA) and its specific attachment to phosphorylated DNA. The concentration of T4 PNK was successfully detected by the TiO₂ NTA electrode with a detection limit of 0.15 U mL⁻¹. In the process, only a one-step incubation process was used and no labeling processes were involved. In addition, the treated TiO₂ foil was anodized into the nanotube array and it was directly used as the electrode without any other complex modification processes which avoided the leakage of an electrode modifier, and so the TiO₂ nanotube array with excellent stability and flexibility is worthy of use in real time monitoring.