TITLE:
Synthesis, Characterization, and Study of PLGA Copolymer in Vitro Degradation
AUTHORS:
Anamaria Teodora Coêlho Rios Silva, Barbara Camilla Oliveira Cardoso, Maria Elisa Scarpelli Ribeiro e Silva, Roberto Fernando Souza Freitas, Ricardo Geraldo Sousa
KEYWORDS:
Synthesis, Characterization, In Vitro Degradation, PLGA
JOURNAL NAME:
Journal of Biomaterials and Nanobiotechnology,
Vol.6 No.1,
January
6,
2015
ABSTRACT: The poly(lactic-co-glycolic acid), known as PLGA, is one of the main bioreabsorbable polymers
used in the field of medicine today. This copolymer is widely applied in sutures, devices geared
toward the controlled release of medication, and the guided regeneration of bone tissue as it
presents a short degradation time. This work aimed to synthesize the 82/18 PLGA (expressed by
the mass ratio of D,L-lactide and glycolide, respectively), to characterize and study the in Vitro degradation
in the form of rods in phosphate buffer solution (PBS). The copolymer was synthesized
by opening the cyclic dimer rings of the monomers D,L-lactide and glycolide, in the presence of the
tin octanoate initiator and of the lauryl alcohol co-initiator. The characterization of the copolymer
and the follow-up of its in vitro degradation were studied using: Differential Scanning Calorimetry
(DSC), Thermogravimetry (TG), Infrared Molecular Absorption Spectroscopy with Fourier Transform
(FTIR), Rheometry, and Scanning Electron Microscopy (SEM). Through these characterization
techniques, it was possible to obtain the glass transition temperature, thermal stability, chemical
composition, morphology, and molar mass of both the synthesized and the degraded copolymer.
The molar mass of the synthesized copolymer was, approximately, 106 g·mol-1. The degradation
rate of PLGA significantly increased from the 19th to the 28th day in PBS. After 28 days in PBS, the
glass transition temperature and the molar mass reduced from 45°C to 17°C and from 1.5 × 106 g·mol-1to 7.5 × 104g·mol-1, respectively. The pH of the medium has a significant influence on the
copolymer degradation profile. When it diminishes, it accelerates the degradation process, resulting
in smaller PLGA polymer chains. This pH dependent degradation can be useful for drug release
systems.