Radionuclide induced modulation of poly (lactic acid) biomaterial properties

Abstract This study investigated how therapeutic-level irradiation influences the physicochemical and biological stability of poly (lactic acid) sheets used for implant positioning and related biomedical applications during radionuclide therapy. Film-grade PLA samples were exposed to controlled I-131 activity conditions for 24 h, corresponding to calculated absorbed doses of 0, 0.4 Gy, 40 Gy, and 280 Gy in control, low exposure (LE), medium exposure (ME) and high exposure (HE) groups, respectively. Following irradiation, the materials were evaluated for physical, chemical and biological changes, where mechanical performance, crystallinity, surface structure, molecular alteration, hydrophobicity, biological performance (in vitro physiological stability and biofilm formation) were assessed. The findings revealed a clear dose-related alteration in PLA characteristics. Post irradiation, a dose-related enhanced mechanical performance, crystalline reorganization, surface smoothening, chemical alterations, hydrophobicity bacterial biofilm formation and enzymatic (Proteinase K) degradation was observed. Low to medium radiation exposure affected relative crystallinity of PLA, marginally improving its mechanical performance and increasing susceptibility to enzymatic degradation. The highest exposure caused marked increases in tensile strength, crystalline organization, surface hydrophobicity, smoothness and densification. The maximum load and tensile stress increased by approximately 37% in the HE group relative to the Control. However, the exposure also led to approximately 20% greater Proteinase K-mediated mass loss after 28 days compared with the control and a 16.7% increase in surface hydrophobicity (contact angle of 75.2° vs. 64.4° in the Control), together with enhanced bacterial biofilm formation. These findings indicate that therapeutic radionuclide exposure can alter both the mechanical microstructural organization and biological stability of PLA biomaterial. Although irradiation may transiently enhance mechanical performance with increasing radiation dose, it simultaneously increases bacterial biofilm formation susceptibility and enzymatic degradability, which may influence the material’s long-term in vivo stability in radiation-associated clinical environments. Further material stabilization strategies should be considered for safe deployment of such biodegradable polymers in radionuclide-based therapeutic settings.