Objective: To study the effects of ultraviolet (UV) light-treatment on the physicochemical properties and bioactivity of micro-arc oxidation (MAO) titanium surfaces in vitro.
Methods: The pure titanium were prepared using MAO. MAO titanium samples were treated with 15 W bactericidal lamp UVC [λ = (250 ± 20) nm] or 15 W mercury lamp [λ = (360 ± 20) nm] for 24 h under ambient conditions. Three sample groups were prepared: MAO, UVA treated after MAO (MAO + UVA), UVC treated after MAO (MAO + UVC). The surface physicochemical properties were evaluated using scanning electron microscopy (SEM), contact angle measuring device, energy dispersive X-ray spectrometer (EDX), and X-ray diffraction (XRD). Bicinchoninic acid (BCA) based colorimetric detection was used to quantify the percentage of albumin adsorption after 2 h, 6 h, and 24 h incubation on the titanium surfaces. The rates of MG-63 cells attached to each group titanium surfaces were calculated by nucleus immunofluorescence using Hoechst 33342 after 1 h, 2 h, and 4 h incubation. SEM was used to observe cell morphology on titanium surfaces in each group.
Results: No obvious differences in surface topography, TiO(2) crystal and elemental composition were detected on titanium surfaces with or without UV treatment. Statistically significant difference in contact angles among MAO + UVC group (65.34 ± 1.16)°, MAO + UVA group (44.64 ± 1.28)°, and MAO group (3.41 ± 0.48)° were found (P < 0.001). The percentage of albumin adsorption reached the plateau after 2 h incubation on MAO + UVC titanium surfaces (48.16 ± 1.24)%, which was higher than those in MAO [(8.22 ± 2.99)%] and MAO + UVA groups [(5.29 ± 2.27)%, P < 0.001]. The rates of cells attached to the surfaces of MAO + UVC titanium was greater than that on MAO surfaces and MAO + UVA surfaces after 1 h [(40.71 ± 4.08)%], 2 h [(53.72 ± 2.38)%], 4 h [(70.32 ± 2.85)%] incubation (P < 0.05). The MAO + UVC surfaces remarkably enhanced the spread of MG-63 cells, however, there was no significant difference between the group of MAO and MAO + UVA.
Conclusions: Pretreatment of micro-arc oxidation titanium with UVC light considerably improved the surface bioactivity to MG-63 cells, which showed an increase in cellular attachment and spread.