In order to prevent and control the effects of pesticide residues on human health and the ecological environment, the rapid, highly sensitive, and selective detection of multiple pesticide residues has become an urgent problem to be solved. Herein, a lab-on-a-molecule probe based on a host−guest complex (ThT@Q[8] probe) has been developed to simultaneously analyze multiple aromatic pesticides under single wavelength excitation, such as fuberidazole, thiabendazole, carbendazim, thidiazuron, and tricyclazole. The fluorescence titration spectra of the ThT@Q[8] probe with the five pesticides mentioned above showed that the fluorescence intensity exhibited a good linear correlation with the pesticide concentration and the limit of detection was as low as 10 −7 M. Because the ThT@Q[8] probe exhibits diverse fluorescence color changes to the five pesticides studied under a 365 nm ultraviolet lamp, we fabricated a single probe used to detect multiple analytes in the RGB triple channel by extracting the RGB variations. Principal component analysis and linear discriminant analysis proved that the ThT@Q[8] probe can recognize and distinguish five pesticides and can be applied at different concentrations. In real samples, the ThT@Q[8] probe recognized and distinguished five pesticides in tap water and Huaxi River water. The 1 H NMR spectra results proved that a charge-transfer complex of ThT and pesticides in the Q[8] cavity may be formed. Moreover, we selected a test strip as a carrier to detect pesticides. The results indicate it can be used to quickly and conveniently detect different pesticides due to the rapid color change. Besides, the ThT@Q[8] probe has good cell permeability and can be used to detect pesticide residues in living cells. This work has laid the foundation for the qualitative and quantitative multitarget detection of pesticide residues.

No abstract

The host−guest interaction between hexamethyl cucurbit [5]uril (HmeQ[5]) and 1,4-diaminobenzene (DB) was investigated, and a new low-molecular-weight supramolecular gel was prepared by a simple heating/mixing cooling method. The structure and properties of the supramolecular gel were characterized. Results revealed that DB molecules did not enter the cavity of HmeQ [5] and that hydrogen bonding between the carbonyl group at the HmeQ[5] port and the DB amino groups, together with dipole−dipole interactions and outer wall interactions, were the main driving forces for the formation of the supramolecular gel. The HmeQ[5]/DB gel system exhibits temperature sensitivity. The phosphor 6-bromo-2-naphthol (BrNp) was embedded in the gel to give the gel fluorescent phosphorescence double emission. The double emission ability at room temperature can be attributed to the ordered microstructure of the supramolecular gel, which effectively avoids the nonradiative transition of BrNp. Meanwhile, HmeQ[5]/DB-BrNp has good biocompatibility and low biotoxicity, which is compatible with HeLa cells to achieve cytoplasmic staining of HeLa in the red channel. The supramolecular gels constructed by this supramolecular assembly strategy not only have good temperature sensitivity but also extend the application of Q[n]s in biomedical fields.

No abstract

No abstract