| With the rapid development of modern science and technology and economy, human also faces increasingly serious pollution and safety problems. More and more pollutants and hazardous substances have entered into food, and have posed a grave threat to human’s health, so the request for pollutant detection becomes higher and higher. Molecular imprinting technology (MIT), a technique to prepare polymers with recognition site for given molecules, has receive great concerns and become a research hotspot owing to its unique properties of structure predictability, recognition specificity and application universality. It has been widely applied to food analysis in recent years.Cholesterol plays important roles in organisms and also is strongly correlated with various cardiovascular diseases. The identification and measurement of cholesterol as biomarker are crucial in many fields, such as clinical diagnosis, food safety and environmental monitoring.In this work, a novel colorimetric sensor for cholesterol assay was constructed by combining MIT with photonic crystals. The molecularly imprinted photonic hydrogel (MIPH) film was prepared by a non-covalent, self-assembly approach using cholesterol as a template molecule, and exhibited high surface areas, interconnected structures, bicontinuous structures and a highly ordered three-dimensional macroporous structure characterized by scanning electron microscopy under the optimized imprinting conditions. Various factors affecting rebinding of cholesterol are discussed along with recognition specificity studies on its analogues of stigmasterol and ergosterol through estimation of UV-Vis and electrochemical impedance spectroscopy. The MIPH film generated a significantly readable optical signal directly self-reporting within less than2min upon binding cholesterol. The colorimetric measurement of cholesterol concentration strongly relies on the fact that the blue shift effect of the Bragg diffraction peak of the MIPH is gradually enlarged with the increase of cholesterol amounts. The detection level approached10-13g mL-1, which is comparable to that of fluorescence measurements. The simultaneous possession of high selectivity, high sensitivity, high stability, easy operation and being label-free enables this sensor to be potentially applicable for rapid on-site detection of trace cholesterol。 Sudan dyes (Sudan Ⅰ, Ⅱ, Ⅲ, and Ⅳ) are phenyl-azoic derivatives with an orange-red appearance and extensively used to color waxes, oils, petroleum, solvents, and polishes. As the illegal use of dyes has major economic consequences for world-wide food industries as well as an impact on public health, simple, reliable, rapid, and cheap-to-runanalytical method is required.A new single-hole hollow molecularly imprinted polymer (SHH-MIP) was prepared by multistep seed swelling polymerization using Sudan I as template molecule and successfully applied to selective solid-phase extraction (SPE) of Sudan dyes in chilli sauce samples. The polymers possessed high specific surface area obtained by nitrogen adsorption and good thermal stability without decomposition lower than380℃by thermogravimetry analysis. Much higher binding capacity of the SHH-MIP was exhibited than that of irregular solid MIP prepared by bulk polymerization, because most of the binding sites were located in the surface of the polymers, facilitating template removal and mass transfer. Accordingly, the SHH-MIP was employed as SPE adsorbent for chilli sauce analysis and offered high recoveries for Sudan I in the range of87.5-103.4%with the precision of1.94-5.33%at three spiked levels. The SHH-MIP with high selectivity and high stability was demonstrated to be potentially applicable for high selective preconcentration and determination of trace Sudan dyes in complicated samples. |
PDF Full Text Request