A Simple and Selective Fluorescent Sensor Chip for Indole-3-Butyric Acid in Mung Bean Sprouts Based on Molecularly Imprinted Polymer Coatings.

In this paper, we report the preparation of molecularly imprinted polymer coatings on quartz chips for selective solid-phase microextraction and fluorescence sensing of the auxin, indole-3-butyric acid. The multiple copolymerization method was used to prepare polymer coatings on silylated quartz chips. The polymer preparation conditions (e.g., the solvent, monomer, and cross-linker) were investigated systemically to enhance the binding performance of the imprinted coatings. Direct solid-phase fluorescence measurements on the chips facilitated monitoring changes in coating performance. The average binding capacity of an imprinted polymer coated chip was approximately 152.9 µg, which was higher than that of a non-imprinted polymer coated chip (60.8 µg); the imprinted coatings showed the highest binding to IBA among the structural analogues, indicating that the coatings possess high selectivity toward the template molecule. The developed method was used for the determination of the auxin in mung bean extraction, and the recovery was found to be in the range of 91.5% to 97.5%, with an RSD (n = 3) of less than 7.4%. Thus, the present study provides a simple method for fabricating a fluorescent sensor chip for selective analysis.

Novel fluorescent membrane for metronidazole sensing prepared by covalent immobilization of a pyrenebutyric acid derivative.

In the present paper, we report the fabrication of a new sensing membrane for fluorescence detection of metronidazole (MNZ). Briefly, a pyrenebutyric acid derivative, 2-(methacryloyloxy) ethyl-4-(1-pyrenyl) butanoate (MPB) with a double bond, was synthesized and copolymerized with 2-hydroxyethylmethacrylate (HEMA) on the activated glass surface by thermal initiation in the presence of cross-linker. The sensor responds linearly to metronidazole in the concentration range of 1.23~35.48 mg.L(-1) in aqueous solution with a detection limit of 0.36 mg.L(-1). The lifetime is enhanced by covalently immobilizing the pyrenebutyric acid derivative on glass slide, which hinders leaching of the dye from the membrane. The sensor could be regenerated after use by washing in methanol (RSD = 2.42 %), and it shows sufficient stability, and selectivity. Interference of other pharmaceuticals on membrane performance is discussed. The developed membrane has been successfully applied for the direct determination of metronidazole in human serum sample without pretreatment.