An ultrafast dual-mode aptasensor for visual screening of quinine in beverages using a portable POCT platform
摘要
Quinine (QN) is widely used as a flavoring additive in tonic beverages, but excessive intake poses potential health risks, necessitating rapid and reliable on-site monitoring. Here, we report a smartphonebased, dual fluorescent–colorimetric aptasensor (FCApt) that enables quantification of QN within 5 s. The sensing mechanism is based on the target-induced displacement of a cyanine dye from a QN-specific aptamer, resulting in complementary fluorescence quenching and a distinct color transition. This dual-signal response provides inherent self-verification, ensuring both sensitivity and reliability. Integrated into a low-cost, 3D-printed portable device, the FCApt system allows instrument-free detection using smartphone-assisted RGB analysis. The method achieved limits of detection of 0.161 μM (fluorescence) and 0.235 μM (colorimetry) with excellent selectivity against structural analogs. Real-sample analysis demonstrated accurate recovery rates (90–113%) in lake water and beverage matrices without pretreatment. Combining mix-and-read simplicity, ultrafast response, and portability, this platform offers a practical point-of-care testing (POCT) solution for food safety monitoring. The strategy can be readily extended to other small-molecule contaminants, providing a general framework for rapid, on-site chemical analysis in food and environmental applications.