Cyclometalated Iridium(III) Complex-Sensitized NiO-Based-Cathodic Photoelectrochemical Platform for DNA Methyltransferase Assay

Abstract

This work reports an efficient [(C6) 2 Ir(dppz)] + PF 6 − (C6 = coumarin 6 and dppz = dipyridophenazine)-sensitized NiO photocathode and its application in photoelectrochemical (PEC) bioanalysis field for the first time. This dye-sensitized NiO photocathode was found to exhibit a markedly enhanced cathodic photocurrent. A sensitive cathodic PEC platform was proposed integrating the as-prepared photocathode with enzyme-free cascaded amplification strategies of the catalytic hairpin assembly (CHA) and the hybridization chain reaction (HCR) for DNA methyltransferase (MTase) assay. A hairpin DNA(H Dam ) with specific recognition site of Dam MTase in its stem was designed. The site of H Dam was methylated in the presence of Dam MTase and then cut by endonuclease DpnI. The released loop fragment, as an initiator, triggered the CHA circuit and the follow-up HCR circuit, resulting in long dsDNA concatemers on the ITO electrode. Numerous [(C6) 2 Ir(dppz)] + PF 6− were intercalated into dsDNA, and highly efficient signal amplification was realized. Benefiting from the superior iridium(III) complex-sensitized NiO photocathode and effective amplification strategy, a detection limit of 0.0028 U/mL for the determination of Dam MTase was achieved. Moreover, this work further demonstrated that these proposed tactics could be applied to screen Dam MTase activity inhibitors.

Importance of DNA nanotechnology for DNA methyltransferases in biosensing assays

“…In addition, it can selectively detect M.SssI in human serum samples and evaluate the efficiency of M.SssI inhibitors, which is a good reference for the detection of clinical samples. Cai et al 77 reported for the first time an efficient [(C6) 2 Ir(dppz)] + PF 6 À (C6 = coumarin 6, dppz = dipyridazine) sensitized nickel oxide photocathode and its application in photoelectrochemical (PEC) bioanalysis (Fig. 1(F)).…”