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A novel fluorescence sensor based on a porphyrinic zirconium-based metal–organic framework, l-cysteine-modified PCN-222 (l-Cys/PCN-222), was developed to selectively recognize histidine enantiomers and sensitively detect Hg2+. The dual-functional sensor was successfully prepared viathe solvent-assisted ligand incorporation method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption analyses. l-Cys/PCN-222 not only showed a higher quenching response for l-histidine than that for d-histidine with a fast fluorescent response rate of <40 s but also exhibited low detection limits for l- and d-histidine (2.48 μmol L−1and 3.85 μmol L−1, respectively). Moreover, l-Cys/PCN-222 was employed as a fluorescent and visual sensor for the highly sensitive detection of Hg2+in the linear range of 10–500 μmol L−1, and the detection limit was calculated to be 2.79 μmol L−1in surface water. The specific and selective recognition of chiral compounds and metal ions by our probe make it suitable for real field applications.

p-Cresol is a harmful phenolic substance that can cause serious effects on human health even at a low concentration in water. Therefore, the detection of p-cresol in a water environment is particularly important. In this paper, a novel zeolite imidazolate framework-67 (ZIF-67) material with regular morphology was prepared on the surface of graphene oxide doped with silver nanoparticles. The composite was modified on the glassy carbon electrode surface to increase the specific surface area, accelerate the electron transfer rate, enhance the current response and improve the performance of electrochemical sensors. Furthermore, a layer of p-cresol-molecularly imprinted polymer was prepared on the surface of the modified electrode by electropolymerization for the selective, rapid and sensitive detection of p-cresol, which greatly improved the specific recognition of p-cresol. Under optimal conditions, the prepared sensor had a good linear range of 1.0 × 10−10M to 1.0 × 10−5M with a detection limit as low as 5.4 × 10−11M, and it presented excellent reproducibility, stability and selectivity. Moreover, the sensor was successfully applied for the detection of trace p-cresol in a real water environment, providing a reliable assay for sensitive, rapid and selective detection of p-cresol in complex samples.

A two-dimensional (2D) molecularly imprinted photonic crystal (MIPC) sensor for the detection of tetracycline in foods was fabricated. The MIPCs were prepared by a thermal polymerization method with polystyrene 2D photonic crystals (2D-PCs) as the template, tetracycline as the template molecule, acrylamide as the functional monomer, and ethylene glycol dimethacrylate as the crosslinking agent. The detection of tetracycline (TC) using the fabricated MIPC sensor was performed through a visual change in the Debye diffraction ring. Typically, the color of the MIPC turned from red to blue with an 11 mm increase in the diameter of the Debye ring when the TC concentration increased to 10−6mol L−1. The fabricated sensor exhibited high selectivity for TC with a response time less than 10 min compared to that for similar compounds. The sensor maintained high sensitivity after five recycles with recoveries of TC around 88.4% and 91.0% in pork and milk samples respectively. We envision that the MIPC sensor could be applied for the detection of TC in food samples and other complicated systems.