Label-free fluorescence turn-on aptasensor for prostate-specific antigen sensing based on aggregation-induced emission-silica nanospheres.

Fluorescent light-up probes based on aggregation-induced emission (AIE)-active molecules have recently attracted great research interest due to the intelligent fluorescence activation mechanism and high sensitivity. In this work, an AIE-silica nanosphere (SiO2 NP)-based label-free fluorescent aptasensor for the sensitive "turn-on" detection of prostate-specific antigen (PSA) is reported for the first time. The positively charged amino-functionalized SiO2 NPs were used as efficient nanocapturer to electrostatically adsorb single-stranded PSA aptamer (PA) to form SiO2 NP-PA nanocomposite as well as adsorb negatively charged tetraphenylethylene derivative 3 (TPE3) to form AIE-SiO2 NP nanocomposite. The binding of the aptamer to the target PSA could induce a rigid aptamer conformation, resulting in the release of the PA away from the surface of SiO2 NPs. This made the AIE molecules TPE3 aggregate on the SiO2 NP surface and emit high fluorescence. With the advantages of simple design and rapid responses, the proposed aptasensor showed high sensitivity and selectivity for PSA with a detection limit of 0.5 ng/mL. The aptasensor was further applied in human serum samples with satisfactory results. Given its versatility, high selectivity, and sensitivity, the proposed method could be extended to other targets by varying the recognition probes. Graphical abstract An AIE-SiO2 NP-based label-free fluorescent aptasensor for the sensitive "turn-on" detection of PSA is reported for the first time.