Effect on surface character and mechanical property of unsintered hydroxyapatite/poly-l-lactic acid (uHA/PLLA) material by UV treatment.

Materials fabricated with unsintered hydroxyapatite/poly-l-lactic acid (uHA/PLLA) exhibit biological activity and biocompatibility, but are also hydrophobic. This hydrophobicity limits the ability of cells or tissues to adhere to the surface of the material and thereby prevents the materials from exhibiting effective biological activity. In this study, we examined the effects of ultraviolet (UV) treatment on the hydrophobicity of uHA/PLLA. We compared the contact angle, mechanical strength, cell attachment, and cell differentiation capacity between untreated uHA/PLLA and uHA/PLLA treated with UV light. The contact angle of UV-treated uHA/PLLA was significantly reduced compared with that of untreated uHA/PLLA. However, there were no differences in mechanical strength between untreated uHA/PLLA and UV-treated uHA/PLLA. Notably, the ability of cells to adhere to UV-treated uHA/PLLA was significantly increased compared with that of untreated uHA/PLLA. Similarly, there were significant differences between UV-treated uHA/PLLA and untreated uHA/PLLA in alkaline phosphatase assays. These findings demonstrated that UV irradiation of uHA/PLLA improved the surface hydrophilicity without changing the mechanical strength of the material; thus, UV treatment of uHA/PLLA may facilitate the use of this material in biomedical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 191-200, 2018.