Dual-signal amplified photoelectrochemical biosensor for detection of N6-methyladenosine based on BiVO4-110-TiO2 heterojunction, Ag+-mediated cytosine pairs

Herein, a novel dual-signal amplified photoelectrochemical (PEC) biosensor was successfully developed for the highly selective detection of N6-methyladenosine (m6A) methylated RNA. The PEC biosensor comprised BiVO4-110-TiO2 heterojunction and gold nanoparticle decorated MoS2 (MoS2-AuNPs) as the photoactive materials, horseradish peroxidase conjugated biotin (HRP-Biotin) as the enzymatic unit, Ag+-mediated cytosine pairs (C-Ag+-C) as the signal amplification unit, and the anti-m6A antibody as the m6A methylated RNA recognition unit. Following immunoreaction between m6A and the anti-m6A antibody, the C-Ag+-C structure of the hairpin DNA unfolded, yielding the duplex strand DNA (dsDNA) and releasing Ag+ ions. Superoxide ions (O2-) generated by the action of HRP on H2O2 then served as an electron donor, resulting in the deposition of Ag on AuNPs surface and resulting in an increased photocurrent. Based on this change f the photocurrent, m6A could be accurately assayed using this dual-signal amplified PEC biosensor. The biosensor showed high selectivity and a very low detection limit of 1.665 pM for m6A, and was successfully applied to evaluate the content change of m6A in leaves of maize seedling and chicken fetal hepatocytes samples after treatment with chemical mutagen of ethylmethane sulfonate and hormone of insulin, respectively.