Preparation,Characterization And Specific Recognition Of Molecularly Imprinted Layer Coated On Silica Particles

In rent years, food security events occurred frequently in worldwide, which bruised seriously the consumer confidence. Therefore, it has been focused on novel detection technologies related to food regulation. Because of the complexity of food matrices and low concentration of analyte（trace level） in food, the analysis of target requires extensive sample pretreatment prior to instrument analysis. However, the sample pretreatment methods generally used in laboratory such as Liquid-liquid extraction（LLE） and Solid phase extraction（SPE） etc, could not recognize selectively target analytes, leading to a great interference in qualitative or quantitative determination. Therefore, it is urgent to develop a highly efficient and convenient sample pretreatment method with specific selectivity for the target molecules.Molecularly imprinted polymers（MIPs） is a novel polymer material with specific recognition for the target molecules. It has been an increasing investigation field adopting surface molecular imprinting technique（SMIT） to prepare SMIPs at the surface of nano or micro particles. Compared with the conventional MIPs, SMIPs are of outstanding advantages, such as rapid mass transfer, short adsorption time and specific recognition capacity. In this work, three novel surface molecular imprinted polymers（SMIPs） were prepared with rhodamine B（Rh B） banned added into food and dibenzyl Phthalate（DBz P） used in food packaging material as template molecular.These SMIPs were characterized by FT-IR, TEM, SEM, as well as adsorption determination, and also applied in real samples. The main contents of research in the paper were listed below:（1） Preparation of molecularly imprinted nanoshell-coated silica nanoparticles for recognition and determination of Rh BA molecularly imprinted nanoshell was prepared successfully by using RhB as template and SiO₂ nanoparticles as supporter based on the combination of the sol-gel method and SMIT. The imprinted particles（Rh B-SMIPs） were characterized by FT-IR, TEM and SEM. Meanwhile, a series of adsorption experiments were performed to investigate the adsorption characterization of the Rh B-SMIPs. The kinetic adsorption of Rh B-SMIPs showed the equilibrium adsorption was within 20 min and the adsorption behavior was in accordance with the pseudo-second-order model. Simultaneously, the static adsorption was carried out at different temperature and p H, and these experimental data were fitted by using Langmuir isotherm model and Scatchard model, respectively. The result indicated that the Langmuir isotherm model yielded a better fit with high regression coefficient for the adsorption process than Freundlich model. Scatchard analysis suggested that the Rh B-SMIPs had only one binding site with homogeneous distribution trait. The Rh B-SMIPs also showed excellent selectivity to Rh B in presence of Ly, Chd, Org and Sy. The rebinding capacities of Rh B-SMIPs remained 87.3% after ten cycles of adsorption-desorption under the relatively mild regeneration conditions, The cycle adsorption result displayed the Rh B-SMIPs were long-life. Rh B-SMIPs/UPLC could be used to analyze Rh B in red wine and beverage with recoveries in the range of 91.6-93.5%,and the relative standard deviation less than 5%.（2） Preparation of monodisperse molecular imprinted nanoshell based on surface of silica microsphere for recognition and determination of DBz PA molecularly imprinted nanoshell was prepared successfully by using DBzP as template and silica microspheres as supporter based on sol-gel and seed-mediated growth synthesis, as well as SMIT. The imprinted particles（DBz P-SMIPs） were characterized by FT-IR and SEM. Meanwhile, a series of adsorption was performed to investigate the adsorption characterization of DBz P-SMIPs. The kinetic adsorption of DBz P-SMIPs was up to equilibrium ca.30 min and the adsorption behavior was in agreement with the pseudo-second-order model. At the same time, the static adsorption was investigated at different temperature, and the experimental data were described by Langmuir isotherm model, Freundlich isotherm model and Scatchard model. The results indicated that the Langmuir isotherm model is more suitable for the adsorption process than Freundlich model. The maximum adsorption amount was up to 62.65 mg·g-1 by Langmuir fitting at ambient temperature. The Scatchard analysis indicated that DBz P-SMIPs contained only one binding site with homogeneous distribution shell. The DBz P-SMIPs also showed excellent selectivity to DBz P in presence of DMP, DCHP, DBP and DOP. Simultaneously, the method for the determination of DBz P in plastic package samples via the DBz P-SMIPs coupled with UPLC was developed. The method was also successfully applied to the analysis of DBz P in two spiked plastic package samples with average recoveries in the range of88.8-93.1% with the relative standard deviation lower than 6%.（3） Preparation of monodisperse high dense dual-template imprinted nanoshell based on the surface of silica microsphere for recognition and determination of Rh B and DBz PA high dense dual-template imprinted nanoshell was prepared successfully by using Rh B and DBz P as co-template molecules and silica microspheres as supporter based on the same method as the third chapter. The imprinted nanospheres（DSMIPs）were characterized by FT-IR and SEM. Meanwhile, a series of adsorption was carried out to investigate the adsorption properties of DSMIPs, The kinetic adsorption of DSMIPs reached equilibrium within 45 min and the adsorption behavior was in accordance with the pseudo-second-order model for Rh B and DBz P, respectively. The static adsorption results demonstrated that the Langmuir isotherm model is more compatible for the adsorption process than Freundlich model. The maximum adsorption amount of DSMIPs arrived at 42.31 and 37.81 mg·g-1 for Rh B and DBz P by Langmuir fitting, respectively. The Scatchard analysis suggested that the DSMIPs had two binding site, corresponding to the imprinting process of Rh B and DBz P. The DSMIPs also showed excellent selectivity to Rh B and DBz P than Ly, DCHP and Pm B.A method of DSMIPs/UPLC was developed for the selective isolation and enrichment of Rh B and DBz P were 86.37%-92.76% and 84.52-91.26% with the RSD lower than6% and 5.2% in two beverage samples, respectively.