PREPARATION OF MOLECULARLY SURFACE-IMPRINTED MATERIAL OF CAFFEINE SUBSTITUTION (THEOPHYLLINE) AND ITS MOLECULE RECOGNITION CHARACTER

By adopting sulfydryl-benzoyl peroxide redox initiating system, the surface-initiated graft-polymerization of glycidyl methacrylate (GMA) on micron-sized silica gel particles was first realized, obtaining grafted particles PGMA/SiO2 with a high grafting degree, and then the ring-opening reaction of the epoxy groups of the grafting macromolecule PGMA with 5-aminosalicylic acid (ASA) was carried out, leading to bonding salicylic acid (SA) onto the side chains of the grafting macromolecule PGMA and resulting in the functional grafting particles SA-PGMA/SiO2. The chemical structure and surface-electrical property of SA-PGMA/SiO2 particles were characterized. The interaction between the functional grafting particles SA-PGMA/SiO2 and theophylline molecule as the substitute of caffeine was examined in depth. The investigation result shows that there exist strong secondary bond forces between the functional grafting particles SA-PGMA/SiO2 and theophylline molecules, including electrostatic interaction and hydrogen bonding. On that basis, the molecular imprinting towards the grafted SA-PGMA was performed with theophylline as template molecule and ethylene glycol diglycidyl ether (EGDE) as crosslinking agent by using the novel surface-molecular imprinting technique established by our research group, and the theophylline molecule-imprinted material MIP-SAP/SiO2 was prepared. With diprophylline and matrine as two contrast compounds, both static and dynamic methods were adopted to investigate the binding properties and molecule recognition character of MIP-SAP/SiO2 for theophylline molecule. The experiment results show that MIP-SAP/SiO2 have specific recognition selectivity and excellent binding affinity for theophylline. Relative to the contrast substance, diprophylline, the coefficient of recognition selectivity of the imprinted material MIP-SAP/SiO2 for theophylline is equal to 7.72, displaying excellent recognition selectivity for the template molecule.