(532c) Hydrogel-Nanofiber Composite Systems for Drug Delivery— Kinetics of Fiber Hydrolysis and Drug Release

Poly(lactide-co-glycolide) (PLGA) is a biodegradable and biocompatible material, which leads to its promising application for drug delivery. Electrospinning is a technique that can fabricate micron or submicron sized polymer fibers from PLGA. The resulting porous, fibrous sheet is favorable for drug delivery. Embedding the electrospun fibrous sheets in a poly(vinyl alcohol) (PVA) hydrogel can provide mechanical strength for implantation and added diffusion barriers for drug release. The drug release rate is partially dependent on the rate of hydrolysis of the PLGA fibers. The fiber morphology, which is impacted by the polymer concentration, molecular weight, and process parameters (tip-to-plate distance and flow rate), may affect the rate of hydrolysis.

PLGA fibers are incubated at 37oC phosphate buffered saline (PBS) solution (pH = 7.4). Dry weight loss, morphology and molecular weight changes will be used to evaluate the hydrolysis. Fibers are found to shrink at incubation conditions. The effect of incorporated protein (such as myoglobin) on PLGA hydrolysis is also investigated. PVA hydrogels embedded with PLGA fibers are incubated at similar conditions. We find that the presence of the PVA hydrogel can prevent PLGA fibers from shrinking during swelling.

Protein release study is conducted by incubating PVA hydrogels embedded with protein-incorporated fibers in PBS solution (pH = 7.4) at 37oC. In order to relate fiber hydrolysis with protein release from hydrogel composites, we will also study the protein release from PLGA fibers containing the model drug. Protein concentration in PBS solution during incubation period will be measured to determine the protein release rate. We will build the connection between hydrolysis of PLGA fibers and protein release so that we can predict and control the protein release rate. The ultimate goal of this research is to design an efficient and time-independent protein-release device.