Lipase-catalyzed copolymerization of lactic and glycolic acid with potential as drug delivery devices

The copolymerization of lactic and glycolic acid (PLGA) using Candida antarctica lipase B as biocatalyst has been achieved with the aim to generate useful biomedical materials. The influence of the reaction conditions, such as solvent and temperature, on the enzyme's catalytic activity was studied to optimize the synthetic procedure. The evaluated parameters were the conversion, the isolated PLGA and the number average molecular weight (M(n)). The identification and purity of the products were assessed by FTIR and NMR. The conversion was determined using analytical titration and the M(n) through end-group analysis. It was found that PLGA oligomers were obtained with satisfactory conversion levels when isopropyl ether was employed as solvent. The use of toluene increased the M(n) but decreased the isolated polyester. Higher percentages of recovered PLGA were reached increasing the temperature from 60 to 80 degrees C using toluene, while a reduction in the M(n) was evidenced under these conditions.