摘要：Analytical performance and efficiency are two pivotal issues for developing an on-site and real-time aptasensor for cadmium (Cd2 ) determination. However, suffering from redundant preparations, fabrications, and incubation, most of them fail to well satisfy the requirements. In this work, we found that fluorescence intensity of 6-carboxyfluorescein(FAM)-labeled aptamer (FAM-aptamer) could be remarkably amplified by 3-(N-morpholino)propane sulfonic acid (MOPS), then fell proportionally as Cd2 concentration introduced. Importantly, the fluorescence variation occurred immediately after addition of Cd2 , and would keep stable for at least 60 min. Based on the discovery, a facile and ultra-efficient aptasensor for Cd2 determination was successfully developed. The sensing mechanism was confirmed by fluorescence pattern, circular dichroism (CD) and intermolecular interaction related to pKa. Under the optimal conditions, Cd2 could be determined rapidly from 5 to 4000 ng mL−1. The detection limit (1.92 ng mL−1) was also lower than the concentration limit for drinking water set by WHO and EPA (3 and 5 ng mL−1, respectively). More than a widely used buffer, MOPS was firstly revealed to have fluorescence amplification effect on FAM-aptamer upon a given context. Despite being sensitive to pH, this simple, high-performance and ultra-efficient aptasensor would be practical for on-site and real-time monitoring of Cd2 .
