Decoding the influence of human serum albumin on the degradation behavior of PLA films produced with green solvent.

Abstract

Polylactic acid (PLA) is gaining prominence in biomedical fields due to its favorable physicochemical characteristics, such as biodegradability and biocompatibility. This study investigates the degradation behavior of PLA films fabricated with dimethyl carbonate, a green solvent alternative to traditional chloroform, and sterilized via UV-C irradiation. Two degradation pathways were examined: exposure to ultraviolet radiation (photodegradation) and immersion in a simulated body fluid (m-SBF) buffer (physiodegradation), with and without human supplementation of serum albumin (HSA). Surface properties such as zeta potential, hydrophobicity, surface tension, and chemical composition were evaluated before and after degradation. Prolonged UV-C photodegradation resulted in chemical activation of the surface, which modulated subsequent interactions with the physiological environment. More specifically, an increase of the negative surface charge and a slight reduction of the surface free energy were observed. Photodegradation enhanced subsequent physiodegradation, as evidenced by greater surface polarity and ion adsorption. Immersion in m-SBF led to increased hydrophilicity, while HSA presence during immersion influenced the formation of biointerfacial layers, markedly shifting the surface to a superhydrophilic and nearly neutral electrical state. Analytical techniques such as time-of-flight secondary ion mass spectrometry identified the presence of nitrogen-containing fragments indicative of protein attachment. Notably, UV-C exposure reduced protein adsorption, suggesting changes in surface affinity.