Dual-model photoelectrochemical biosensor via DNAzyme walker integrated nanoprobe for ultrasensitive ratiometric detection of microRNA-155

Abstract

Ultrasensitive detection for low concentration and abnormal expression of microRNA-155 (miR-155) in serum (fM level) at the early stage of cancer still exist great challenges. Therefore, a dual-model photoelectrochemical biosensor was developed based on label-free trimetallic nanoprobe and Mg2+ dependent DNAzyme driven DNA walker to generate ratiometric dual-signal output for sensitive biosensing of miR-155 from breast cancer cells (MCF-7) and cervical cancer cells (HeLa). In signal amplification strategy, PtCo@Prussian Blue nanozyme was selected as a signal nanoprobe with high catalytic activity and large specific surface area, while two dimensional MXene/AuNPs as surface modification material was applied to improve the active sites of the electrode. With the presence of the target, the DNAzyme assisted DNA walker process was initiated and abundant signal nanoprobe was introduced to the electrode surface, producing high current response and weak ultraviolet-visible spectrophotometry (UV–vis) response. Hence, the biosensor for miR-155 shows a low limit of detection of 1.2 fM from the linear range of 5 fM to 5 nM, exhibiting excellent stability and reproducibility. Moreover, the proposed biosensor demonstrates superior performance for miR-155 in complex human serum samples and tumor cell lysates, presenting great application potential for early-stage clinical diagnosis.