Boosting the biodegradation and bioactivity of PBS-DLS copolymers via incorporation of PEG

Biodegradable polymers play a crucial role in the development of materials for biomedical applications. This study investigates the enzymatic biodegradation, bioactivity, and cytotoxicity of poly(butylene succinate-dilinoleic succinate) (PBS-DLS) copolymers modified with poly(ethylene glycol) (PEG). Two copolymer variations with different segmental compositions (70 wt% and 60 wt% of hard segments) were synthesized. After modifying the copolymers with PEG, the presence of a lipase catalyst accelerated degradation after 20 days, evidenced by reduced residual content. Gel permeation chromatography analysis showed up to 40% decrease in molecular weight, while gravimetric analysis indicated a mass loss of up to 10% during enzymatic degradation. Morphological examination revealed that the enzymatic breakdown, facilitated by hydrolase activity (boosted by the presence of PEG), resulted in surface erosion, holes, cracks and changes in spherulitic morphology. It highlights the tunable degradation pathways of these copolymers. Bioactivity studies demonstrated the formation of biomimetic calcium/phosphate (Ca/P) crystals, with varying stoichiometry based on segmental composition. Copolymers with higher crystallinity (70 wt% hard segments) favored tricalcium phosphate-like crystal formation, while those with lower crystallinity (60 wt% hard segments) were more susceptible to hydroxyapatite precipitation. In vitro cytotoxicity tests using mice fibroblasts exhibited excellent cell viability and attachment for all copolymers. These findings highlight the significance of these copolymers in developing biodegradable materials for medical applications. The ability to control degradation through PEG modification, along with their bioactivity and cell compatibility, positions them as promising candidates for diverse biomedical applications.