Hydrolytic Degradation Study of Polyphosphazene-PLGA Blends

Authors

Riley BlumenfieldFollow

Date of Completion

Spring 5-1-2020

Thesis Advisor(s)

Cato Laurencin

Honors Major

Materials Science and Engineering

Disciplines

Biomaterials | Biomedical Devices and Instrumentation | Molecular, Cellular, and Tissue Engineering | Polymer and Organic Materials

Abstract

The synthesis and in vitro degradation analysis of thin films of poly[(glycineethylglycinato)₇₅(phenylphenoxy)₂₅phosphazene]
(PNGEG₇₅PhPh₂₅) and poly[(ethylphenylalanato)₂₅(glycine-
ethylglycinato)₇₅phosphazene] (PNEPA₂₅GEG₇₅) blended with poly(lactic-co-glycolic acid) (PLGA) was conducted to determine the blends’ potential for use as scaffolding materials for tissue regeneration applications. The samples were synthesized with glycylglycine ethyl ester (GEG) acting as the primary substituent side group, with cosubstitution by phenylphenol (PhPh) and phenylalanine ethyl ester (EPA) to make the final product [1]. Blends of 25% polyphosphazene, 75% PLGA and 50% polyphosphazene, 50% PLGA were analyzed throughout the study. It was found that by the four-week mark, the degradation of all blends had led to a similar low pH near 2.7. The blends of PNGEGPhPh-PLGA did not degrade as expected throughout the course of the study, with the 50-50 blend seeing a less than 40% mass loss and the 25-75 blend seeing a just over 60% mass loss. Through FTIR analysis, it was found that all samples degraded first at the intermolecular hydrogen bonds, leading to a separation of the polyphosphazene component and the PLGA. From there, the PNGEGPhPh-PLGA and PNEPAGEG-PLGA blends broke down differently - the former broke down into intramolecularly-bonded polymer microspheres, while the latter did not. Treating the pH data from this experiment as an outlier, as it did not agree with FTIR results or pH results from other studies, the blend should be successful in reducing acidity and subsequent pain at insertion sites as compared to pure PLGA [2]. However, further investigation is suggested, as the consistency of pH results shown in this study is concerning.

Recommended Citation

Blumenfield, Riley, "Hydrolytic Degradation Study of Polyphosphazene-PLGA Blends" (2020). Honors Scholar Theses. 779.
https://digitalcommons.lib.uconn.edu/srhonors_theses/779