Hollow molecularly imprinted polymer based quartz crystal microbalance sensor for rapid detection of methimazole in food samples.

In this study, a novel detection method of methimazole was proposed based on the hollow molecularly imprinted quartz crystal microbalance (QCM) sensor, in which the hollow imprinted polymers (H-MIPs) were firstly prepared through the surface imprinted techniques, using hollow silica spheres as matrix supporting material and methimazole as template molecule. The characterizations of H-MIPs were carefully studied. Compared with traditional MIPs, H-MIPs exhibited faster mass transfer rate and higher adsorption capacity. After coating onto the surface of Au chip, the H-MIPs QCM sensor was fabricated. Based on the frequency shift, good linear behavior in the range of 5-70 µg L-1, limit of detection of 3 µg L-1, and good recoveries of 88.32%-107.96% in the spiked pork, beef and milk were obtained. The analysis process could complete within 8 min. The developed sensor provided an effective, fast and accurate method for the methimazole detection in food samples.

Photoresponsive hollow molecularly imprinted polymer for trace triamterene in biological samples.

This paper reports a photoresponsive hollow molecularly imprinted polymer for the determination of trace triamterene in biological sample. The photoresponsive hollow molecularly imprinted polymer was prepared on sacrificial silica microspheres via surface imprinting technique through atom transfer radical polymerization using a novel water-soluble azobenzene derivative, 4-[(4-methacryloyloxy)phenylazo]-3,5-dimethyl benzenesulfonic acid, as the functional monomer, and the sacrificial silica core was subsequently removed using HF etching method with 1.25vol.% HF ethanolic solution. The morphologies and properties of the photoresponsive hollow molecularly imprinted polymer were further characterized and compared systematically with the corresponding photoresponsive surface molecularly imprinted polymer. Compared with surface imprinted polymer, the hollow material displayed higher binding capacity, better recognition ability, faster mass-transfer rate, and larger isomerization rate constants toward triamterene. The static binding properties of the imprinted materials were investigated under three irradiation conditions. The photoresponsive hollow molecularly imprinted polymer showed better specificity toward triamterene than its structural analogues (folic acid and caffeine) as examined by UV-vis and HPLC. The photoresponsive hollow molecularly imprinted polymer was utilized for the determination of trace triamterene in biological samples (human urine and serum) with advantages of simple sample pre-treatment, good recovery and good sensitivity.

Photoresponsive hollow molecularly imprinted polymer for the determination of trace bisphenol A in water.

A photoresponsive hollow molecularly imprinted polymer (PHMIP) was fabricated for photoresponsive recognition and determination of trace bisphenol A (BPA) in aqueous media using a water-soluble azo compound as the functional monomer. The PHMIP was prepared on sacrificial silica microspheres by surface imprinting and subsequent removal of the silica core. The PHMIP displayed photocontrolled recognition for BPA. SEM, TEM, FT-IR, TGA and N2 adsorption-desorption analyses confirmed successful formation of the hollow structure. The PHMIP displayed higher binding capacity, a larger specific area, and faster mass transfer rate than its corresponding surface molecularly imprinted polymer. The PHMIP was used to determine trace BPA in real samples with a limit of detection of 0.5ppm. For samples spiked at 0-10ppm, the BPA recoveries were in the range of 93.0%-99.0%. This PHMIP-based method provides convenient and inexpensive detection method for trace BPA in environmental samples. This method is especially suitable for determining materials that do not possess specific spectroscopic or luminescent properties.