Molecular imprinting of caffeine and its recognition assay by quartz-crystal microbalance

Phase inversion precipitation method was applied to prepare molecularly imp rinted polyacrilonitrile (PAN) copolymers. Three types of PAN copolymers wi th pyridine and styrene moieties were used for caffeine (CAF) imprinting. F or encoding shape of the template molecules into the polymer, polymer solut ion involving the template molecule was coagulated in water non-solvent. Af ter the template extraction from the resultant polymer, binding amounts of CAF and CAF analogous molecules to the CAF-imprinted polymer were evaluated by using 6 MHz quartz-crystal microbalance (QCM). As QCM attached with CAF -imprinted polymer was immersed into CAF solution, the QCM frequency decrea sed and then saturated at constant value. We demonstrated recognition prope rties of the CAF-imprinted polymers by observation of the frequency change for various imprinted and unimprinted polymers. It was observed that PAN co polymer having 4-vinylpyridine (4-Py) moieties showed a large difference of the frequency decrease between the imprinted and unimprinted polymers. Evi dence was presented that the CAF-imprinted polymer having 4-Py moieties hig hly recognize CAF molecules. Also, the selectivity of the CAF-imprinted pol ymers was investigated using CAF analogous molecules. (C) 2001 Elsevier Sci ence B.V. All rights reserved.