A class-specific artificial receptor-based on molecularly imprinted polymer-coated quantum dot centers for the detection of signaling molecules, N-acyl-homoserine lactones present in gram-negative bacteria.

Herein, a novel class-specific artificial receptor-based on molecularly imprinted polymer (MIP)-coated quantum dots (QDs@MIP) was synthesized, characterized, and used for the detection and quantification of the bacterial quorum signaling molecules N-acyl-homoserine lactones (AHLs), a class of autoinducers from Gram-negative bacteria. The QDs@MIP was prepared by surface imprinting technique under controlled conditions using CdSe/ZnS QDs as the signal transducing material. The synthesis of the QDs@MIP was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, and fluorescence spectroscopy. After template elution, the obtained cavities sensitively and selectively recognized the target AHLs of interest. The fluorescence intensity of the QDs@MIP was significantly quenched compared to the control non-imprinted polymer (QDs@NIP) upon exposure to different AHL concentrations. It also had a good linearity in the range from 2 to 18 nM along with a detection limit of 0.66, 0.54, 0.88, 0.72 and 0.68 nM for DMHF, C4-HSL, C6-HSL, C8-HSL and N-3oxo-C6-HSL, respectively. Most interestingly, the proposed sensor exhibited high sensitivity, good stability and fast response (30 s) towards the target molecules due to successful formation of surface imprints. The practicability of the developed sensor in real samples was further confirmed through the analysis of bacterial supernatant samples with satisfactory recoveries ranging from 89 to 103%. According to these results, the as-prepared QDs@MIP can be used as a new potential supporting technique for the rapid and real-time detection of bacterial pathogens in food safety and healthcare facilities.