Wavelength-resolved photoelectrochemical biosensor triggered by cascade signal amplification reactions for RNA methylation analysis on a single interface

Among ribonucleic acid (RNA) methylation modifications, those of m(6)A and m(5)C are the two most abundant forms, and the bias of m(6)A and m(5)C modification levels plays an essential role in many biological processes. Therefore, constructing a mechanism that can simultaneously analyze the two modifications would be potentially very significant. Herein, we propose a wavelength-resolved photoelectrochemical (PEC) biosensor based on cascade signal amplification reactions for m(6)A-RNA and m(5)C-RNA analysis on a single interface. First, a target sequence was transformed with antibody-functionalized magnetic beads to obtain the initial sequences, triggering the 3D DNA nanomachine to transform and amplify targets by generating many output sequences. Subsequently, the output sequences were combined with rolling-circle-amplification (RCA) primer scaffolds, and then a DNA origami structure was formed based on RCA. A DNA origami could immobilize many photo electrochemical mediators to amplify photocurrent responses. As expected, the proposed PEC biosensor exhibited excellent analytical performances for both m(6)A-RNA and m(5)C-RNA. The detection limits were as low as 1.96 fM and 7.37 pM, respectively. The successful fabrication of the PEC biosensor opened new possibilities for epigenetic research and the diagnosis and treatment of methylation-related diseases.