Temperature-sensitive driving assembled fluorescence hydrogel based dual-mode sensor for adsorbing and detecting of heavy metal cadmium ions in food and water

The denatured bovine serum albumin (dBSA) is coupled with the CdTe/CdS quantum dot and the resulting CdTe/CdS@dBSA complex is assembled and retained in the poly(n-isopropyl acrylamide) (PNIPAM) hydrogel via regulating temperature and pH to form the CdTe/CdS@dBSA-PNIPAM fluorescence hydrogel substrate, which is able to adsorb and sense cadmium ions (Cd²⁺). Based on this fluorescence hydrogel, a fluorescence and colorimetric dual-mode detection system is established to quantitatively detect Cd²⁺ with a limit of detection (LOD) of 2.88 nM for fluorescence detection and 11.66 nM for colorimetric detection. Here, the fluorescence and colorimetric detection mode can obtain the dual test signal including the fluorescence signal and visual orange-red color signal. Therein, the utilization of smartphone can achieve the conversion of visual color signals into RGB digital signals, facilitating the interconnection of data among the communication devices. This research provides a novel and advanced strategy for the accurate and real-time detection of Cd²⁺.