David Spencer


Biodegradable hydrogels are of interest for drug delivery applications due to their resemblance to biological tissue and their ability to absorb large amounts of biological fluids. Here, hydrogels were synthesized from multiple macromers to demonstrate step-wise degradation and multiphase drug release profiles. Control over the degradation and release profiles of multiple macromer hydrogels has potential applications in implantable, extended release drug delivery devices in which removal would not be needed after administration. Herein, macromers were synthesized from diethylene glycol diacrylate (A), poly(ethylene glycol) diacrylate (n=400) (H), and isobutylamine (6) in 1.2:1 molar ratios of total diacrylate to amine with diacrylate ratios of A:H (0:1), (1:1), and (2:1). Multiple macromer hydrogels were synthesized via UV photo polymerization with a 365nm UV flood source and an intensity of 8-10mW/cm2. Degradation and swelling studies were conducted gravimetrically, and fluorescence correlation spectroscopy (FCS) was used to track diffusion coefficients at different stages of degradation. Degradation for the fully degradable systems used was inconclusive, while degradation for the non-degradable systems demonstrated a two-stage release. Swelling was found to increase with hydrophilic character of the hydrogels. Fluorescently tagged lysozyme, trypsin, and bovine serum albumin were loaded into the multiple macromer hydrogels and release was tracked using fluorescence spectroscopy. A triphasic drug release was not achieved for the systems used; however, release was tuned by varying the mass ratios of the hydrogel components.