Design of molecularly imprinted hydrogels with thermoresponsive drug binding sites
Yuto Toyoshima, Akifumi Kawamura, Yoshinori Takashima, Takashi Miyata
Abstract
-isopropylacrylamide) (PNIPAAm) hydrogels without CD ligands, drastically shrunk above their transition temperature because of the PNIPAAm major chains changing conformation from a hydrophilic random coil to a hydrophobic globule as temperature increased. Because the MIP hydrogel has dynamic molecular binding sites, it absorbs a larger amount of dapsone than the NIP hydrogels in an aqueous solution below the transition temperature. The amount of dapsone adsorbed into the MIP hydrogel significantly decreased with increasing temperatures above 37 °C, despite the fact that the hydrophobic interaction between the polymer chains and dapsone became strong. The decrease in dapsone adsorption capability of the MIP hydrogel is due to a conformational change from a swollen to a shrunken state as temperature increases. The MIP hydrogel suppressed drug leakage below its transition temperature due to the high binding capacity of dynamic binding sites, but accelerated the drug release above its transition temperature due to the collapse of dynamic molecular binding sites, in contrast to the drug release behavior of general PNIPAAm-based hydrogels. Thus, the thermoresponsive MIP hydrogels with dynamic molecular binding sites regulated drug release in response to a change in temperature.