Monte Carlo simulation of poly(lactic-glycolic acid) films degradated in simulated body fluid

Min QI; Hongze LIU; Zhiyong WEI; Yingying HUANG

ABSTRACT

BACKGROUND:

Poly(lactic-co-glycolic acid) (PLGA) has been widely used as medical implants and drug vehicle. Due to various factors involved in the degradation process, it is rather difficult to simulate the mass loss properties of PLGA.

OBJECTIVE:

To investigate the mass loss properties of PLGA films, and observe the correlation between the stimulation and the factual measurement.

DESIGN:

Repeated measuring experiment.

SETTING:

School of Materials Science and Engineering, Dalian University of Technology.MATERIALS PLGA 5050, 7030 and 7525 with weight average molecular weight (Mw) of 63 000, 115 000 and 400 000 were purchased from Shandong Key Laboratory of Medical Polymer Materials, and 1,4-dioxane (analytically pure) was purchased from Tianjin No.1 Chemical Reagent Factory and used as solvent.

METHODS:

The experiments were carried out in the School of Materials Science and Engineering of Dalian University of Technology from April to July in 2006.①PLGA were dissolved in 1, 4-dioxane according to the mass ratio of 5050, 7030 and 7525, and the solution were cast into 10 mm×10 mm×1 mm polymer films.②PLGA films were immersed in Hank's simulated body fluid (Ph 7.4) at 37 ℃, and then taken out every week (every 5 days for PLGA 5050). The samples were washed and dried to measure the changes of number and Mw using gel permeation chromatography. Degradation velocity was also worked out. Meanwhile the mass loss properties of PLGA films were measured using electronic balance. Furthermore, an improved Monte Carlo method was applied to carry out the correlation analysis with experiment data. MAIN OUTCOME

MEASURES:

①degradation rates of PLGA with different ratios of lactic acid and glycolic acid.②the correlation coefficient between simulation results and experiment data.

RESULTS:

①The degradation rates for PLGA at 5050, 7030 and 7525 were 0.058 5, 0.016 6 and 0.010 1 /d (based on Mn), or 0.061 0, 0.017 5 and 0.008 5 /d (based on Mw), respectively.②Correlation coefficients between simulation results and experiment data for PLGA 5050, 7030 and 7525 were 0.973 6, 0.987 4 and 0.990 3 correspondingly.

CONCLUSION:

The numerical simulation results for the mass loss properties of PLGA fit the experiment data well.