Enzyme-free amplified and one-step rapid detection of bisphenol A using dual-terminal labeled split aptamer probes

Novel enzyme-free amplified dual-terminal labeled split aptamer (SPA) probes were developed to achieve one-step rapid and sensitive detection of bisphenol A (BPA). By rational split, the original aptamer was divided into two segments named SPA-a and SPA-b to achieve target-driven self-assembly and form BPA/SPA complex. To achieve enzyme-free signal amplification and improved sensitivity, SPA probes were dual-terminal labeled with 6-carboxyfluorescein (FAM) fluorophores and black hole quencher 2 (BHQ2). Two dual-terminal labeled SPA probes were induced to assemble a ternary complex with BPA to produce fluorescence resonance energy transfer effect, generating the decreased fluorescence intensity. The detection limit of dual-terminal labeled SPA probes was 0.89 ng/mL, which was 24-fold lower than that of single-terminal modification. Meanwhile, these SPA probes showed a rapid response to BPA, which could be completed in 5 min for one-step detection without complex cleaning and separation progress. The recovery rates in real samples were 94.17% to 107.28%. In brief, the dual-terminal labeled SPA probes showed substantial potential for onsite detection of BPA.