APE1 mediated target-responsive structure switching electrochemical (SSE) biosensor for RNA detection

Abstract

Structure switching caused by the contact between nucleic acids plays an important way for transmit information. Target-responsive structural switching strategy is a promising tool in the development of biosensors. Herein, an apurinic/apyrimidinic endonuclease 1 (APE1) mediated target-responsive Structure Switching Electrochemical (SSE) biosensor was developed for RNA detection. The method is established on that a toehold-mediated hairpin ssDNA, with AP site modified at a specific position, serves as a target capturer and structural transformer and modified on the gold electrode. By target-responsive catalytic hairpin assembly (CHA), the switch of AP sites in double-strand and single-strand is realized. Subsequently, the specifically cleavage of AP site by APE1 achieve the electronical signal output. Both “turn-on” and “turn-off” signal output strategies were design. Under optimal conditions, the SSE biosensor presented wide linear range both in “turn-on” (10 fM to 100 nM) and “turn-off” (1 fM to 100 nM) modes with a LOD as low as 4.5 fM and 0.6 fM respectively. The specificity and reproducibility of the method are satisfactory. To demonstrate the practical applications of this biosensor, we have successfully validated its performance in detecting Strawberry Mottle Virus (SMoV) from strawberry leaf samples. These results highlight the simplicity, high specificity, and sensitivity of this biosensor platform, making it a promising tool for RNA detection.