A Novel Media-Concentration Based Accelerated Hydrolytic Degradation Model for Biodegradable Polymers Based on Time-Concentration Superposition Frameworks

Percutaneous fetoscopic surgery is a promising intervention for treating fetal conditions but is frequently complicated by premature preterm rupture of membranes (PPROM), largely due to chorioamniotic membrane separation at the site of laparoscopic entry. A novel surgical technique developed at Texas Children's Hospital - suturing the membrane to the uterine wall around the cannula - has dramatically reduced PPROM rates. To further this innovation, our lab developed the ChorioAnchor, a bioresorbable fixation device composed of poly(lactide-co-glycolide) (PLGA) anchors and a poly(4-hydroxybutyrate) (P4HB) suture, designed to percutaneously secure the fetal membrane during surgery and safely degrade postnatally. Understanding and predicting the degradation behavior of bioresorbable polymers is essential for medical device development. In this study, the hydrolytic degradation of polyglycolide (PG) was investigated in both real-time (PBS) and accelerated (NaOH) media to explore the validity of a Time-Concentration Superposition (TCS) framework applied to accelerated degradation tests in terms of their ability to predict real time degradation response. Samples were evaluated across multiple metrics, including mass loss, mechanical strength, thermal transitions, inherent viscosity, and structural/morphological changes. Degradation behavior was found to be highly dependent on NaOH concentration, with high concentrations (1N, 0.3N, and 0.1N) inducing surface erosion and low concentrations (0.03N, PBS) inducing bulk degradation. These mechanisms were distinguishable based on molecular, structural, and morphological evidence. A three-parameter Weibull model reasonably described degradation profiles across all media concentrations. Log-time shift values were extracted at degradation thresholds and used to construct a unified degradation timeline via a Williams-Landel-Ferry (WLF) shift model. While this TCS-WLF approach successfully aligned degradation data, it was most representative of real time degradation only at low NaOH concentration. The study concludes that NaOH concentration not only accelerates degradation but also alters the underlying degradation pathway for polyglycolide (PG), and potentially for other esters, like poly-lactides and PLGA, which needs further investigation. As such, any concentration-based shift model must account for mechanistic differences in the mode of degradation to remain physically meaningful. This work establishes a foundation for standardized, concentration-based media-accelerated degradation testing and highlights the importance of mechanism-aware modeling in the evaluation of bioresorbable materials.

Name thesis:degree_name

Master of Science

Discipline thesis:degree_discipline

Biomedical Engineering

Grantor

Texas A&M University

Year dc:date.issued

2025

Author dc:creator

• Garibaldi, Dylan Lee 2001-

Advisor dc:contributor.advisor

• Haridas, Balakrishna

Committee members dc:contributor.committeemember

• Mabbott, Samuel
• Sukhishvili, Svetlana

• Engineering, Biomedical

Handle dc:identifier.uri

https://hdl.handle.net/1969.1/1600381

OAI record oai:identifier

https://oaktrust.library.tamu.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aoaktrust.library.tamu.edu%3A1969.1%2F1600381