Rapid sensitive fluorescence detection of cadmium (II) with pyrene excimer switching aptasensor

Heavy metal cadmium (II) contamination often occurs, causing great health risk to human due to high toxicity of cadmium (II). Rapid, sensitive and simple detection of cadmium (II) are of great importance in environmental monitoring. Taking advantage of aptamer in specific recognition, easy modification, and capability of binding-induced structure change, here we reported a simple fluorescent sensor with rapid and sensitive response for Cd²⁺ using aptamer pyrene excimer switch. The aptamer was labeled with dual pyrene molecules at two ends of the sequence. The binding of Cd²⁺ to this aptamer probe brought the pyrene labels into close proximity and enhanced formation of a pyrene excimer, which generated increased fluorescence at 485 nm. By measuring the fluorescence of pyrene excimer, we achieved detection of Cd²⁺ with this aptasensor. Under the optimum experimental conditions, the detection limit of Cd²⁺ reached nanomolar levels. This method was selective and allowed for the detection of Cd²⁺ in tap water. This fluorescence aptasensor is promising for rapid detection of Cd²⁺ in broad applications.