Preparation Of Molecular Imprinting Polymer On Silica Gel Articles For Alkaloid And Specific Binding Property

Alkaloid is the main active ingredient contained in Chinese herbal medicine and thevarious alkaloids have different pharmacological activities. But it is very complicated topurify the alkaloid. This paper investigates the synthesis of novel adsorption materialsfor matrine and cytisine, and researches the adsorption character and mechanism. Theexperimental results have important reference values for separating alkaloid.Firstly, Micro-sized silica gel particles were first surface-modified with couplingagent γ-mercaptopropyl trimethoxysilane （MPMS）, obtaining the modified particlesMPMS-SiO₂, on which mercapto groups were chemically introduced. Subsequently, Aredox initiation system was constituted with the mercapto groups on the surfaces ofMPMS-SiO₂particles and benzoyl peroxide （BPO） in a solution, and the“surface-initiated graft-polymerization” of glycidyl methacrylate （GMA） was realized,achieving the grafted particles PGMA/SiO₂with a high grafting degree of23g/100g,andthen the ring-opening reaction of the epoxy groups of the grafting macromoleculePGMA with5-aminosalicylic acid （SA） was carried out, leading to bonding salicylicacid （SA） onto the side chains of the grafting macromolecule PGMA and resulting in thefunctional grafting particles SA-PGMA/SiO₂.The adsorption capacity and adsorption mechanism of SA-PGMA/SiO₂for alkaloidin water is further studied. The experimental results show that the functional particleSA-PGMA/SiO₂has strong adsorption ability for alkaloid. The driving force of theadsorption is the synergism of electrostatic and hydrogen bond interaction. Theadsorption capacity has a maximum value at pH=7for theophylline and pH=8formatrine.The reaction temperature can exert great effect on the adsorption property ofSA-PGMA/SiO₂, and the adsorption capacity is decreased with the increase of thetemperature. Then, the molecular imprinting towards the functional particle SA-PGMA/SiO₂wasperformed with alkaloid theophylline as template molecule and ethylene glycoldiglycidyl ether （EGDE） as crosslinking agent, and the theophylline molecule-imprintedmaterial MIP-SAP/SiO₂was prepared. Both static and dynamic methods were adopted tostudy the binding properties and molecule recognition character of MIP-SAP/SiO₂fortheophylline. The experiment results show that MIP-SAP/SiO₂possess strongrecognition capability for theophylline. In relation to diprophylline, the selectivitycoefficient of SA-PMA/SiO₂for theophylline is0.810, and that of MIP-SAP/SiO₂fortheophylline is7.720. Besides, MIP-SAP/SiO₂has excellent elution property.Finally, MIP-SAP/SiO₂was prepared with matrine as a template molecule andEGDE as crosslinking agent, and by right of the intermolecular hydrogen bond andelectrostatic interactions between the grafted SA-PGMA macromolecules and matrinemolecules. Both static and dynamic methods were adopted to study the bindingproperties and molecule recognition character of MIP-SAP/SiO₂for matrine. Theexperiment results show that MIP-SAP/SiO₂possess strong recognition capability formatrine. In relation to cytisine, the selectivity coefficient of SA-PGMA/SiO₂for matrineis1.270, and that of MIP-SAP/SiO₂for matrine is11.166, and in relation to oxymatrine,the selectivity coefficient of MIP-SAP/SiO₂for cytisine is increased from0.943to5.659.Besides, MIP-SAP/SiO₂has excellent elution property.