Antibody-free photoelectrochemical strategy for simultaneous detection of methylated RNA, METTL3/METTL14 protein and MazF protein based on enhanced photoactivity of MoSe2–BiOI nanocomposite

Taking advantages of the catalytic activity of METTL3/METTL14 protein towards adenine methylation in RNA sequence and the specific digestion activity of MazF protein towards unmethylated RNA sequence containing ACA bases, a novel photoelectrochemical biosensor was constructed for simultaneous detection of RNA methylation, METTL3/METTL14 protein and MazF protein. MoSe2-BiOI nanocomposite was prepared and considered as photoactive material, catalytic hairpin assembly strategy and in situ generation of electron donors catalyzed by polyaspartic acid-loaded alkaline phosphatase technique were employed as signal amplification. Under the optimum conditions, the detection ranges of methylated RNA, METTL3/METTL14 protein and MazF protein were 0.001-50 nM, 0.001-25 ng/μL, and 0.001-10 U/mL, respectively. The corresponding detection limits were 0.46 pM, 0.51 pg/μL and 0.42 U/μL with S/N = 3. In addition, the effect of drugs and composite pollutants on the activities of MazF proteins was assessed, proving the applicability of the developed method in the field of drug screening for MazF-related diseases. Moreover, the effects of pollutants on the activity of METTL3/METTL14 were also preliminarily explored, providing new information on pathogenic mechanism of pollutants.