Cascade amplifying aptasensor for positively correlated detecting OTA: Based on DNase I-assisted cyclic enzyme digestion and AgNPs@gel-enhanced fluorescence

To improve the performance of aptasensor, the coupling of novel material and strategy had been the hottest research with the promising prospects. In this study, a cascade amplifying aptasensor (CA-aptasensor), which had coupled the DNase I-assisted cyclic enzyme digestion and AgNPs@gel-enhanced fluorescence, had reflected the desired performance for positively correlated detecting OTA . For this purpose, the GO@PVP was used to adsorb and quench the free FAM-Apt, while the complex of OTA and FAM-Apt was digested by the DNase I. The released OTA allowed the free FAM-Apt to separate from the GO@PVP cyclically, thus the OTA level was amplified preliminarily. The AgNPs@gel could combine with the released FAM to form the metal enhanced fluorescence (MEF) effect, resulting in the cascade signal amplification. The OTA was detected at pg mL −1 level with an ultrasensitive LOD of 3.33 pg mL −1 and IC 50 of 13.6 pg mL −1 , which improved 90-fold and 728-fold than that of ELASA for same aptamer. The CA-aptasensor indicated high specificity, reliability and practicability. Meanwhile, the CA-aptasensor exhibited more highlights, including the efficient homogeneous system, low background signal and standardized aptamer recognizer. This study might provide a new approach for improving the performance of aptasensor, which could also guide the signaling cascade and positively correlated detection for other risk factors.