Catch & release thiol reactive hydrogels

Abstract

Hydrogels have attracted remarkable attention since they have high potential uses in many fields. They are commonly used in tissue engineering, drug delivery systems, biosensors and wound healing dressings. Recently, there is a great interest in fabricating well defined functionalizable hydrogels and hydrogel micropatterns. This study has three parts. In the first part, PEG-based, reversible-thiol reactive hydrogels containing various amount of pyridyl disulfide functional group were synthesized by photopolymerization in the presence of photoinitiator and PEGDMA crosslinker. Swelling studies were conducted and surface morphology of the hydrogels were examined by scanning electron microscopy (SEM). Time-dependent pyridothione release profiles of the bulk hydrogels provided with using glutathione (GSH) were obtained using via UV-vis spectroscopy. As expected, it was found that release of pyridothione depends on thiol-disulfide exchange reaction mechanism. In the second part of the study, PEG-based 3D, reversible-thiol reactive hydrogel micropatterns were fabricated by photopolymerization. Immobilization of thiol containing fluorescent dye, BODIPYC10SH onto the hydrogel micropattern were performed and release of the immobilized molecules from the surface were achieved using GSH and dithiothreitol (DTT). Thiol containing biotin derivatives were covalently attached to the thiol reactive hydrogel micropatterns under mild condition. Immobilization of TRITC-extravidin onto biotinylated hydrogel micropatterns and release of immobilized molecules from the surface were performed using DTT and investigated using fluorescence microscope. In the third part, thiol-reactive orthogonally functionalizable bulk hydrogels containing pyridyl disulfide functional group in certain ratio and additionally various amount of furan protected maleimide functional group were synthesized by photopolymerization. Thermogravimetric analysis of these hydrogels were conducted to demonstrate control over monomer incorporation.