A sensitive photoelectrochemical immunoassay of N6-methyladenosine based on dual-signal amplification strategy: Ru doped in SiO2 nanosphere and carboxylated g-C3N4

Abstract A novel, simple and sensitive photoelectrochemical (PEC) immunosensing platform was constructed for detecting N 6 -methyladenosine (m 6 A) based on the carboxylated CN and avidin functionalized Ru@SiO 2 (ARS) nanocomposite. Herein, the N 6 -methyladenosine-5′-triphosphate (m 6 ATP) was selected as the detection target molecule, m 6 A antibody was used as recognition unit for m 6 A, the carboxylated g-C 3 N 4 (CN) was not only used as the photoactive substance, but the substrate for the m 6 A antibody immobilization, ARS was synthesized and used as signal amplification unit to improve the photocurrent of CN, Phos-tag-biotin was employed as bridge of m 6 ATP and Ru@SiO 2 through the specific interaction between phosphate group of m 6 ATP and Phos-tag, biotin and avidin, respectively. Under the optimal condition, the fabricated PEC biosensor showed a linear range of 0.01–10 nM and high detection sensitivity with low detection limit of 3.23 pM for m 6 ATP. Besides, the developed strategy was also successfully applied to evaluate the content of m 6 A in human serum samples.