In vitro drug controlled-release behavior of an electrospun modified poly(lactic acid)/bacitracin drug delivery system

Abstract

Poly(lactic acid-co-lysine) (PLL) was applied as a modified material to improve the hydrophilicity, reactivity, and degradation rate of poly(L-lactic acid) (PLLA). In the drug delivery system, PLLA and PLLA/PLL were selected as the carrier materials of drug-loaded fibers, and bacitracin (BAC) as the sustained release drug. Uniaxial drug-loaded fibers (PLLA/BAC, PLLA/PLL/BAC) and coaxial drug-loaded fibers ((PLLA/PLL/BAC)-PLLA, (PLLA/BAC)-(PLLA/PLL)) were prepared using electrospinning. The chemical structures and thermal properties of the electrospun drug-loaded fibers were analyzed using Infrared Spectroscopy (IR) and Differential Scanning Colorimetry (DSC) separately and an Ultraviolet spectrophotometer (UV) was used to characterize the extracorporeal drug releasing behavior. The results indicated that the main interaction between the BAC and carrier materials such as PLLA and PLLA/PLL was physical force; the uniaxial drug-loaded fibers with uniform diameters showed a higher release rate compared with the coaxial drug-loaded fibers owing to the protection of shell materials in the coaxial fibers. The drug release rate of the drug-loaded fibers increased due to the addition of hydrophilic PLL; the drug release mechanism in both the uniaxial and coaxial drug delivery systems could be interpreted by a biexponential-biphase kinetics function. Two kinds of fibers with different drug release patterns could be fabricated by uniaxial and coaxial electrospinning. Drug in uniaxial fibers could be quickly released and was suitable for antibiotic treatment while the release of drug in coaxial fibers was a kind of controlled release which could be applied for a drug delivery system of long-term and small doses.