MXene enhanced BiVO4/Bi2S3 heterojunction combined with 3D DNA walkers and HCR cascade signal amplification strategy for detection of NSCLC-associated miRNAs

Accurate and sensitive microRNA (miRNA) assays are critical for the early detection of non-small cell lung cancer (NSCLC). Herein, a novel photoelectrochemical (PEC) biosensing platform based on MXene/BiVO4/Bi2S3 integrated with a cascade signal amplification technique was innovatively developed for NSCLC-related miRNA-486–5p detection. Specifically, BiVO4/Bi2S3 heterojunction served as the photoanode material, which was prepared by a facile anion exchange process. To further enhance the photoactivity, the BiVO4/Bi2S3 heterojunction and MXene were utilized to generate energy band-matched structures that improve the migration kinetics of photogenerated carriers. The addition of the target miRNA-486–5p triggered the 3D DNA walker process, resulting in the release of DNA sequences to initiate the hybridization chain reaction (HCR), followed by the generation of abundant DNA duplexes for the immobilization of the enzyme-mimicking manganese porphyrin (MnPP). Subsequently, MnPP actively participated in catalyzing the oxidation of 4-chloro-1-naphthol (4-CN) to generate insoluble precipitates on the MXene/BiVO4/Bi2S3 surface that significantly quenches the PEC signal. Taking advantage of the initial high photocurrent of the MXene/BiVO4/Bi2S3 photoanode as well as the target-induced amplification technique. The proposed PEC strategy demonstrated satisfactory photocurrent responses toward miRNA-486–5p detection with a limit of detection of 0.35 fM, in the 1.0 fM to 1.0 nM range. The current study aimed to provide a practical tool for NSCLC diagnosis and to present an effective biosensor method for detecting low-concentration biomolecules.