Effect of Alkaline Treatment on the Bioactivity of Poly（lactic acid）（PLA）Films <i>in Vitro </i>

The advancement of bioactive scaffolds for tissue regeneration stands as a fruitful domain within polymer chemistry. Particularly in dentistry, scaffolding materials play a vital role in treating periodontal diseases and facilitating implant treatments for regenerating the maxillomandibular complex. In this research, we engineered a poly（lactic acid）（PLA）film, a biodegradable polymer, with enhanced physiological activity. The PLA film underwent hydrolysis through KOH treatment to modify its surface. The weight loss of PLA-KOH in phosphate-buffered saline solution（PBS, pH = 7.4）was assessed in comparison to pure PLA. Significantly, PLA-KOH exhibited a higher weight loss than PLA, with values of 4.8% and 3.1%, respectively, after 91 days of immersion（p < 0.05）. The introduction of carboxylic acid was achieved through 0.5M KOH hydrolysis, and the precipitation of apatite on the PLA film was confirmed after immersion in Hanksʼ Balanced Salt Solution（HBSS, pH 7.4）without organic species for 1, 3, 7, 14, 21, and 28 days at 37℃. Scanning electron microscopy illustrated faster and larger precipitation on the PLA-KOH film compared to PLA after 28 days of HBSS immersion. The formation of hydroxyapatite on both PLA and PLA-KOH films following HBSS immersion was substantiated by X-ray diffraction（XRD）. This HBSS immersion experiment effectively demonstrated the bioactivity of both PLA and PLA-KOH.