Hanin Alkhamis (Teltow, DE), Dr. Shivam Saretia (Teltow, DE), Dr. Rainhard Machatschek (Teltow, DE), PD Dr. Axel Thomas Neffe (Teltow, DE), Dr. Katarzyna Polak-Kraśna (Teltow, DE)
Abstract text (incl. figure legends and references)
Introduction
Degradable polyesters such as polyglycolide, polylactide, and poly(ε-caprolactone) have been extensively used in biomedicine.Their high crystallinity, and in some cases high Tg, prevents easy deformability and high limit of elastic recovery. Recently, hyperelasticity was shown in poly[(L-lactic acid)-co-caprolactone] (PLLAcoCL), blended with poly(D-lactic acid) (PDLA).1Understanding the mechanisms of degradation, as well as controlling the degradation rate and mechanical properties, are of importance for developing applications for such (bio)degradable polyesters.2
Objectives
Simultaneous measurement of degradation profiles and mechanical properties of PLLAcoCL/PDLA blends in a controlled environment at different pH values, oxidative conditions, or presence of enzymes.
Materials and Methods
Electrospun meshes, and 30x15x0.1mm films of PLLAcoCL/PDLA (95:5) were prepared for bulk hydrolytic degradation in PBS at 37°C over a time period of 4 months. Moreover, ultrathin films of PLLAcoCL,PDLA,and blends (95:5, 90:10, 85:15, and 80:20) were prepared and degraded at the air-liquid interface using the Langmuir technique coupled with interfacial rheology. The ultrathin films are degraded by the addition of proteinase K (0. 02µg/ml), 3% hydrogen peroxide, hydrochloric acid (0.3M), or potassium hydroxide (pH12).
Results
Ultrathin films degrade fastest with KOH and H2O2, while degradation with proteinase K was slowest.The shear strength of the films rapidly reduced preceding the phase of rapid mass loss. No degradation-induced crystallization was observed. Bulk degradation took longer, but followed the same behavior.
Conclusion
Hyperelastic PLLAcoCL/PDLA blends showed hydrolytic, oxidative, and enzymatic degradability with a predictable change in mechanical properties. Langmuir film degradation experiments align in trend for the rate of degradation with bulk experiments enabling faster studies.
Nanomaterials2021
Macromolecular Rapid Communications2019