Supramolecular hydrogel mediated photoelectrochemical/electrochemiluminescence dual-mode biosensor based on TiO/CdInS/CdS for sensitive detection of enrofloxacin.

In this paper, a new photoelectrochemical (PEC) and electrochemiluminescence (ECL) dual-mode biosensor based on TiO/CdInS/CdS (TO/CIS/CdS) composite and a unique supramolecular hydrogel quenching probe was constructed for sensitive detection of enrofloxacin (ENR). Firstly, TO/CIS/CdS showed excellent PEC and ECL dual signals, which was applied to dual-mode sensing and detection. By using cyclic amplification and magnetic separation techniques, target ENR was converted into a large number of product chains with ZnO nanoparticles (NPs), and acidolysis was carried out to obtain zinc ions. Then, a layer of supramolecular hydrogel with good biocompatibility and stability was formed on the electrode using the ligand interaction between adenosine monophosphate (AMP) and Zn. The poor electrical conductivity and light transmission of the hydrogel layer make it an excellent double-quenching material for PEC and ECL signals, which was used for sensitive dual-mode detection of ENR. The cyclic amplification technique in a homogeneous solution was utilized to improve the sensitivity of detection while avoiding the complex electrode-modification process, thus effectively improving efficiency and stability of the sensor. The detection range of the PEC mode can reach 0.1 pg mL to 1 μg mL, and the limit of detection (LOD) is 35 fg mL. The detection range of the ECL mode is from 1 pg mL to 1 μg mL, and the LOD is 0.14 pg mL. Thus, a new multifunctional biosensor utilizing TO/CIS/CS and the unique hydrogel quencher was opened up, which has great potential for application in the field of food safety and environmental monitoring.