A photoelectrochemical biosensor based on Ti3C2Tx MXene/Ag2S as a novel photoelectric material for ultrasensitive detection of microRNA-141

In this work, a novel photoelectric active material Ti3C2Tx MXene/Ag2S with strong photocurrent signal was prepared to construct the photoelectrochemical (PEC) biosensor for ultrasensitive detection of target miRNA-141. Impressively, Ti3C2Tx MXene with excellent metal conductivity could shorten the electron transmission path to prominently improve the separation of electron-hole pairs and significantly enhance the photocurrent signal of Ti3C2Tx MXene/Ag2S nanocomposite. Meanwhile, streptavidin (SA) was used as a scaffold to assemble a DNA tetrad for constructing a spatial DNA structure by a nonlinear hybrid chain reaction (HCR) triggered via target miRNA-141, which embedded amount of thionine as a sensitizer for significantly increasing the photocurrent response. The biosensor could achieve the sensitive detection of miRNA-141 with detection limit of 34 aM. This strategy demonstrated a novel photoactive material to construct the PEC biosensor for sensitive detection of biomarkers with potential application value in disease diagnosis.