Preparation and characteristics of Tryptophan‐imprinted Fe3O4/P(TRIM) composite microspheres with magnetic susceptibility by inverse emulsion–suspension polymerization

Tryptophan-imprinted Fe3O4/P(TRIM) composite microspheres with magnetic susceptibility (MS-SMIPs) were prepared by inverse emulsion–suspension polymerization, according to the principle of molecular imprinting technique, using magnetite Fe3O4 particles as magnetically susceptible component, methacrylic acid (MAA) and acrylamide (AM) as functional monomers, trimethylolpropane trimethacrylate (TRIM) as polymeric matrix components, and hydroxy ethyl cellulose (HEC) as dispersant. The external morphology and the inner structure of MS-SMIPs were observed by SEM. SEM photographs showed that the resulting MS-SMIPs were regularly spherical in external morphology and had a large quantity of spherical microvoids inside. The effects of the amount of Fe3O4 on particle size and morphology of MS-SMIPs were investigated in detail. The results indicated that the amount of Fe3O4 affected particle size distribution and morphology of MS-SMIPs obviously. The magnetic characteristics of MS-SMIPs were measured by vibrating sample magnetometer, and the results showed that the resulting MS-SMIPs had a certain magnetic response to external magnetic fields. Adsorption properties, molecular recognition selectivity, and regeneration recognition selectivity of MS-SMIPs were investigated using tyrosine and phenylalanine as control molecules, and characterized by high performance liquid chromatography. It was shown that the resulting MS-SMIPs exhibited a good recognition selectivity for tryptophan, and the relative separation factor (β) was 2.75, and MS-SMIPs also exhibited higher regeneration recognition selectivity, and the separation factor was 1.83 and 1.80 in first regeneration and second regeneration, respectively. The effect of the amount of functional monomers on molecular recognition selectivity was investigated, and the mechanism of imprinting and recognition was analyzed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3241–3250, 2006