Synthesis and Characterization of Poly(lactic-co-glycolic acid) Derived with LGlutamic Acid and L-Aspartic Acid

Poly(lactic-co-glycolic acid) (PLGA) is a biocompatible, biodegradable polymer approved by the FDA and EMA, which is the most widely used in the field of health. In this study, PLGA was synthesized primarily from lactide and glycolide by polycondensation and ring-opening polymerization. Then, amino acid derivatives of PLGA were synthesized by the reaction of PLGA and amino acids in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The polymers synthesized were PLGA, PLGA-L-glutamic acid (PLGA-G), and PLGA-L-aspartic acid (PLGA-A). The chemical structure of these polymers was confirmed by 1H and 13C Nuclear Magnetic Resonance (1H NMR and 13C NMR), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Gel Permeation Chromatography (GPC). When the 13C NMR analyses of PLGA-amino acid derivatives were observed, an increase in the number of carbonyl carbons around 170 ppm was found and the structure accuracy was supported. In addition, when the FTIR analyses of PLGA-amino acid derivatives were examined, the structure was confirmed by observing the signal of the amide bond carbonyl vibration at 1700 cm-1. While the typical endothermic thermogram of the PLGA-amino acid derivative structures was observed by DSC analysis, it was shown that the structures were low molecular weight polymers [~5000-6000 Da] by GPC analysis.