Thiol reactive hydrogels from single precursor

Abstract

Hydrogels have become very popular materials in last few decades. They have found high potential of use in tissue engineering, drug delivery systems, biosensors and wound healing dressing. Recently, there is a great interest in fabricating well defined hydrogels with easier methods. In this study, functionalizable hydrogels from single precursor were synthesized by convenient way and functionalizations of the hydrogels were done. In the first part, ABA type triblock polymers were synthesized by Atom Transfer Radical Polymerization (ATRP). Linear polyethylene glycol (PEG), polymer was chosen as middle block and it was modified as ATRP initiator. Furan protected maleimide methacrylate (FPMMA), furfuryl methacrylate (FFMA) and oligoethylene methyl ether methacrylate (OEGMEMA) were polymerized using the PEG based macroinitiator using ATRP. Resulting triblock polymers were characterized by gel permeation chromatography (GPC), infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR). The triblock copolymers were activated by retro Diels-Alder (rDA) reaction and crosslinked by Diels-Alder (DA) in situ to obtain hydrogels. Thermogravimetric analysis and water uptake capacity of the hydrogels were done. The nature of crosslinking was examined in presence of anthracene to demonstrate that crosslinking is due to Diels-Alder reaction of maleimide and furan on the polymers. Presence of the scavanger diene anthracene, prohibits hydrogel formation and result in linear polymers containing anthracene-maleimide cycloadducts as side chains. In the second part of the study, by using thiolene chemistry fluorescent BODIPYC10SH molecules were attached to hydrogels to examine functionalization. It is shown that by changing block lengths of the polymers, the control over functional group density is achieved.