Highly Sensitive Photoelectrochemical Biosensor Based on Quantum Dots Sensitizing Bi <sub/>2</sub> Te <sub/>3</sub> Nanosheets and DNA-Amplifying Strategies

摘要： In this work, the Bi2Te3 nanosheets treated by N-vinyl-Pyrrolidinone (NVP) showed the highly sufficient and stable photocurrent for being served as novel photoactive material. Accordingly, with CdTe quantum dots (QDs) sensitizing the Bi2Te3 nanosheets, a photoelectrochemical (PEC) biosensor coupling of DNA amplifying strategies was constructed for sensitive miRNA-21 detection. Initially, the Bi2Te3 nanosheets on electrode have conductive surface states with dissipationless electronic property, thus providing a highly stable photocurrent as well as large surface-to-volume ratio. Then, with the participation of target miRNA-21 and auxiliary DNA, the strand displacement amplification (SDA) took place, thereby opening substantial DNA hairpins for triggering next hybridization chain reaction (HCR). Through the HCR, long DNA tails decorated with CdTe QDs could thus be assembled on electrode for enhancing the photocurrent of Bi2Te3 nanosheets. As a result, the proposed PEC biosensor showed a wide detection range from 10 fM to 100 pM with a detection limit (LOD) of 3.3 fM, displaying a promising avenue to construct simply, ultrasensitive and stable analytical techniques and a tremendous potential in bioanalysis and early clinical diagnosis.