Hydrogel-Nanofiber Composite Systems for Drug Delivery

Ya Liang, Anthony Lowman, and Giuseppe Palmese

Poly(lactide-co-glycolide) (PLGA) is a biodegradable and biocompatible material, which leads to its promising application for drug delivery. Electrospinning technique can fabricate micron or submicron sized polymer fibers from PLGA, and the resulting porous, fibrous mats are favorable for drug delivery. Drugs can be incorporated in fibers during electrospinning. Embedding the electrospun fibrous mats in a poly(vinyl alcohol) (PVA) hydrogel can provide mechanical strength for implantation and added diffusion barriers for drug release. All samples were incubated at 37oC phosphate buffered saline (PBS) solution (pH = 7.4) for PLGA degradation and protein release studies. Dry weight loss, morphology and molecular weight changes of PLGA fibrous mats were used to evaluate the hydrolysis. Fibrous mats were found to shrink, which reduced porosity, when fibers were swollen at incubation conditions. Dry weight loss during incubation was an “S”-shaped curve and fiber morphology had no influence on the hydrolysis rate. However, we noticed that the presence of PVA hydrogel could prevent PLGA fibrous mats from shrinking during fiber swelling. We studied protein release from PLGA fibers and hydrogel-nanofiber composites, respectively. Protein concentrations in PBS solution during incubation were measured to determine the release rate. Since the release rate is dependent on the hydrolysis rate of PLGA and protein diffusion, we hope to build the connection among hydrolysis, diffusion and protein release so that we can predict and control the protein release rate.