Multi-Level Evaluation of UV Action upon Vitamin D Enhanced, Silver Doped Hydroxyapatite Thin Films Deposited on Titanium Substrate

Hydroxyapatite Ca-10(PO4)(6)(OH)(2) (HAp) is an important bioactive material for bone tissue reconstruction, due to its highly thermodynamic stability at a physiological pH without bio-resorption. In the present study, the Ag:HAp and the corresponding Ag:HAp + D-3 thin films (similar to 200 nm) coating were obtained by vacuum deposition method on Ti substrate. The obtained samples were exposed to different UV irradiation times, in order to investigate the UV light action upon thin films, before considering this method for the thin film's decontamination. The effects of UV irradiation upon Ag:Hap + D-3 are presented for the first time in the literature, marking a turning point for understanding the effect of UV light on composite biomaterial thin films. The UV irradiation induced an increase in the initial stages of surface roughness of Ag:HAp thin film, correlated with the modifications of XPS and FTIR signals. The characteristics of thin films measured by AFM (RMS) analysis corroborated with XPS and FTIR investigation highlighted a process of recovery of the thin film's properties (e.g., RMS), suggesting a possible adaptation to UV irradiation. This process has been a stage to a more complicated UVA rapid degradation process. The antifungal assays demonstrated that all the investigated samples exhibited antifungal properties. Moreover, the cytotoxicity assays revealed that the HeLa cells morphology did not show any alterations after 24 h of incubation with the Ag:HAp and Ag:HAp + D-3 thin films.

Automated summary

In this study, Ag:HAp and Ag:HAp + D-3 thin films were prepared on Ti substrate using vacuum deposition method, and the effects of UV irradiation on the thin films were investigated for the first time. The results indicated a process of recovery of the thin film's properties under UV irradiation, leading to a more complex UVA rapid degradation process. Furthermore, antifungal assays showed that all samples exhibited antifungal properties, while cytotoxicity assays revealed no alterations in HeLa cell morphology after incubation with the thin films.