Table of Contents
Advances in Biomaterials
Volume 2014 (2014), Article ID 834942, 9 pages
http://dx.doi.org/10.1155/2014/834942
Research Article

Effect of Hydration on Physicochemical Properties of End-Capped PLGA

1Sunovion Pharmaceuticals Inc., Marlborough, MA 01752, USA
2Department of Drug Sciences, Section of Pharmaceutical Chemistry and Technology, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
3University of Kentucky, College of Pharmacy, Lexington, KY 40536, USA

Received 2 May 2014; Accepted 27 June 2014; Published 13 August 2014

Academic Editor: Fraser Buchanan

Copyright © 2014 Susan D’Souza et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The objective of this study was to assess the physicochemical effects of hydrating a hydrophobic end-capped poly(lactide-co-glycolide) (PLGA) polymer in the liquid and vapor state. PLGA RG503 polymer was incubated at 37°C in 0.5% polyvinyl alcohol (PVA) solution and at 90% RH. Samples were withdrawn at predetermined intervals and changes to polymer properties like glass transition temperature (Tg), moisture uptake, molecular weight change, and % acid number were determined using differential scanning calorimetry, Karl Fisher titrimetry, gel permeation chromatography, and acid base titrimetry, respectively. Study results showed that Tg was depressed instantaneously upon hydration, indicating that bulk water acted as a plasticizer of hydrophobic end-capped PLGA. Tg values decreased to levels below the incubation temperature when hydrated in 0.5% PVA solution but not in 90% RH. The drop in Tg exhibited a linear relationship () to the amount of water uptake by the polymer; higher moisture uptake was noted with liquid water. Removal of moisture from the polymer matrix resulted in recovery of Tg, only up to a period of 14 days. Presence of water in liquid or vapor form caused a reduction in molecular weight of the polymer and a corresponding increase in % acid number over the duration of the study.