A ratiometric fluorescence fiber-optical sensor system (RFFS) merging a Y-type optical fiber spectrometer and CdTe QDs composite functionalized with glutathione and mercaptopropionic acid (GMPA@CdTe-QDs) for highly selective and on-site detection of ciprofloxacin (CIP) in environmental water samples was designed. Our preliminary results suggested that the red fluorescence of the synthesized GMPA@CdTe-QDs was effectively quenched by CIP. Based on this, the RFFS/GMPA@CdTe-QDs system was successfully fabricated and used for highly selective and rapid detection of CIP on site in the concentration range from 0 to 45 μM with the detection limit of 0.90 μM. The established method exhibited good interference resistance to the analogues of CIP and provided a great potential platform for real-time detection of CIP residues in environmental water. In addition, the fluorescence quenching mechanism of GMPA@CdTe-QDs by CIP was also investigated by means of temperature effect, fluorescence lifetime, ultraviolet (UV) visible absorption, and fluorescent spectra. Our results suggested clearly that the red fluorescence of GMPA@CdTe-QDs was quenched by CIP via the photoinduced electron-transfer (PET) mode.

A novel, highly sensitive and fast responsive turn-on fluorescence probe ADMPA for Cd ²⁺ was successfully developed based on 2,9-dimethyl-1,10-phenanthroline and o -aminophenol.

A novel smart sensor for the rapid and label-free detection of benzocaine has been developed based on the combination of photonic crystal (PC) and molecular imprinting polymer (MIP) techniques. A molecularly imprinted photonic crystal (MIPC) hydrogel film was prepared via a non-covalent, self-assembly approach with a PC mould. With a highly ordered inverse opal structure, the resulting benzocaine MIPC exhibited high sensitivity, smart specificity, quick response times and good regeneration abilities. It can give rise to a readable optical signal and color change upon binding with benzocaine, with a detection limit of 16.5 μg mL⁻¹. The sensor has been successfully used to visually estimate benzocaine concentrations in fish samples. In comparison with HPLC, the developed MIPC sensor has shown satisfactory accuracy in terms of results. It has great potential for on-site screening and the visual detection of trace benzocaine in real samples.