Effects of PLGA Composition, Concentration and BSA Loading on Electrospun Nanofiber Geometry and Controlled Drug Release

Abstract: The purpose of this research was to examine how the composition and concentration of the co-polymer poly(lactic-co-glycolic acid) (PLGA) affects the geometry of electrospun nanofibrous matrices for the purposes of drug delivery. The affects of loading bovine serum albumin conjugated with fluorescein (FITC-BSA) into these matrices on fiber geometry were also examined. These fibers were electrospun with an 18-gauge syringe tip, at a collecting distance of 10 cm, at a voltage of 20 kV and at a flow rate of 1.0 ml/hr. These fibers were imaged and analyzed using SEM to determine the average fiber diameter and diameter variability. It was determined that 20 wt% PLGA (50:50) solutions yielded fibers with the most desirable characteristics. At a concentration 15 wt% PLGA for both compositions, beading was present and at a concentration of 25 wt% the average fiber diameter for both compositions increased significantly. The average fiber diameter of 20 wt% PLGA (50:50) fibers was determined to be 1.05±0.19 μm. The average fiber diameter for 20 wt% PLGA (85:15) was determined to be 1.08±0.38 μm. Because of the smaller average fiber diameter and standard deviations of the PLGA (50:50) fibers, this composition of PLGA was used for the purposes of controlled drug release.

PLGA (50:50) solutions of 15, 20 and 25 wt% were then prepared and 0.5 mg/ml of FITC-BSA was added to each solution. The solutions were then electrospun under the same conditions stated previously. It was determined that 20 wt% PLGA (50:50) fibers loaded with FITC-BSA yielded the best fiber characteristics. The average fiber diameter was determined to be 550.48±91.04 nm. To ensure that FITC-BSA was evenly dispersed throughout the fibers, confocal microscopy was used. The fluorescent molecules could be seen in the fibers electrospun with FITC-BSA but could not be seen in the fibers without FITC-BSA. The 20 wt% PLGA (50:50) fibers loaded with FITC-BSA were then submerged in a physiological buffer (PBS) to determine the feasibility of using these fibers as a drug deliver system. It was determined that these fibers could act as a time released drug delivery system as the concentration of FITC-BSA in PBS increased over time.