Product Code: ICA12_M204

Effect of Laser Induced Crystallinity Modification on Biodegradation Profile of Poly(L-Lactic Acid)
Shan-Ting Hsu, Department of Mechanical Engineering, Columbia Univ.; New York NY USA
Huade Tan, Department of Mechanical Engineering, Columbia Univ.; -
Y. Lawrence Yao, Department of Mechanical Engineering, Columbia Univ.; New York NY USA
Presented at ICALEO 2012

The biodegradable polymer such as poly(L-lactic acid) (PLLA) is promising in drug delivery applications because it hydrolyzes into non-toxic substances in physiological environments. However, its induction period of biodegradation prevents the embedded drugs from releasing at the designed rate in the early stage. PLLA degradation profile is a function of crystallinity, and control over surface crystallinity allows for modification of initial drug release profiles. In this study, laser irradiation is used to modify surface crystallinity, and its effect on PLLA biodegradation profile is studied. The wide-angle X-ray diffraction (WAXD) and X-ray photoelectron spectroscopy (XPS) show that laser irradiation reduces surface crystallinity while causes no measurable chemical modifications. As evaluated by molecular weight via gel permeation chromatography (GPC) and weight loss of the material, the reduced surface crystallinity, which has less ordered structure and favors water penetration into the matrix, causes the initial degradation rate to increase, and shortens the induction period of PLLA biodegradation. Based on the hydrolysis reactions and material diffusion during PLLA biodegradation, a model is also developed to numerically investigate the effect of laser irradiation on the biodegradation profile. The reduced induction period of biodegradation potentially gives the ability to tailor the initial drug release to achieve the designed release rate.

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