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

Abstract

Hydroxyapatite Ca10(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 + D3 thin films (~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 + D3 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 + D3 thin films.

Physicochemical and Biological Evaluation of Chitosan-Coated Magnesium-Doped Hydroxyapatite Composite Layers Obtained by Vacuum Deposition

“…Our previous results highlight both compositional and morphological changes in the analyzed samples [30,43]. Furthermore, similar effects were noticed after exposure to UV radiation of silver-doped hydroxyapatite thin films [34].…”

“…The maxima that belong to double-degenerate bending (ν2) are between 400 and 500 cm −1 , and those of triple-degenerate (ν4) of P-O vibration in phosphate groups could be found in the 550-600 cm −1 spectral domain [61]. The vibrational bands that are found in the 1300-1800 cm −1 spectral domain are mainly attributed to N-H, C-H, C-O, and C=O vibration in chitosan structure [34]. Moreover, the FTIR results suggest that with the increase in radiation dose from 3 to 6 Gy, the maxima are slightly displaced and become more broadened.…”

“…Therefore, the new compounds obtained by the development of MgHAp in a chitosan matrix could own enhanced biological and antimicrobial properties [30]. For the deposition of hydroxyapatite composite thin films, various techniques, such as spin coating [32,33], vacuum deposition [34], PLD (pulsed laser deposition) [35], and RF magnetron sputtering [36], are currently available. Among these techniques, vacuum deposition spin coating produces uniform thin films [37].…”