CdS Quantum Dots-Regulated g-C3N4 Electrochemiluminescence and Photoelectrochemical Performance for Multimodal Sensing and Imaging Assay of Vibrio parahaemolyticus

In order to solve the problem of low electrochemiluminescence (ECL) intensity and resolution for imaging detection, we innovatively discovered for the first time that the ECL quantum efficiency of the CdS quantum dots (QDs)/g-C3N4/K2S2O8 system is 18.4 times that of the g-C3N4/K2S2O8 system, so CdS QDs/g-C3N4 displays high-intensity ECL and can be used for mobile phone ECL imaging. In particular, CdS QDs combined with g-C3N4 can produce a new color, from the original blue to green, which greatly improves the ECL imaging resolution and detection sensitivity, thus achieving high-resolution visual ECL analysis of the target. Furthermore, CdS QDs/g-C3N4 also shows excellent photoelectrochemical (PEC) properties. Therefore, a unique multimode sensing and colorimetric imaging platform based on CdS QDs/g-C3N4 is constructed. A Vibrio parahaemolyticus target was induced to produce many S2 through cyclic amplification. The porous magnetic Fe3O4 nanoparticles (NPs) were used to load a large number of CdS QDs, and target-related S2 opened S1 on Fe3O4 NPs to release many CdS QD probes, which can further amplify the signal. After convenient magnetic separation for CdS QDs corresponding to the V. parahaemolyticus target, the released CdS QDs were added to g-C3N4 nanosheets to realize multimode detection of ECL, imaging, and PEC of V. parahaemolyticus. This work not only innovatively found that CdS QDs can change the luminous color of g-C3N4 and CdS QDs/g-C3N4 display high-intensity ECL, but also developed a new PEC-ECL-imaging multimode sensor with excellent performance, which greatly improves the detection sensitivity and accuracy, and makes a significant contribution to the ECL analysis field.