Molecularly Imprinted Polymer Microspheres with Nanopore Cavities Prepared by Precipitation Polymerization as New Carriers for the Sustained Release of Dipyridamole

Imprinted polymers are now being increasingly considered for active biomedical uses such as drug delivery. In this work, the use of molecularly imprinted polymers (MIPs) in designing new drug delivery devices was studied. Imprinted polymers were prepared from methacrylic acid (MAA) (functional monomer), ethylene glycol dimethacrylate (cross-linker), and dipyridamole (DIP) (as a drug template) using precipitation polymerization method. The influence of the template/functional monomer proportion and pH on the achievement of MIPs with nanopore cavities with a high enough affinity for the drug was investigated. The small pores (average 3.9 nm) in the imprinted microspheres show excellent retention properties for the target analyte. The polymeric devices were further characterized by FT-IR, thermogravimetric analysis, scanning electron microscopy, photon correlation spectroscopy, Brunauer-Emmett-Teller analysis, and binding experiments. The imprinted polymers showed a higher affinity for DIP and a slower release rate than the nonimprinted polymers. The controlled releases of DIP from the prepared imprinted polymers were investigated by an in vitro dissolution test by measuring the absorbance at 284 nm by means of a UV-Visible spectrophotometer. Loaded imprinted microsphers showed very slow release in various solutions such as phosphate buffer solution (pH 6.8), HCl (pH 1.0) and mixture of HCl and MeOH at 37.0 +/- 0.5 degrees C and were able to prolong DIP release for more than two days. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1586-1593, 2011