TiO₂ Nanometer Thin Film Influence Adherence And Growth Of Cultured Cell In Vitro

Objective to observe the depressive effect of TiO₂ nanometer thin film on lens epithelium cells (LEC) and macrophages(MΦ) in vitro when it is activated during UVA illumination or after UVA pre-irradiation, and investigate its influence on surface cellular proliferation and adherence.Methods TiO₂ membrane was formed on glass substrate and studied with naked glass plate as control. This study consisted of two parts. In part one ,TiO₂ coated plate or naked plate were exposed to different magnitude of UVA(0.102mw/cm² and 0.825mw/cm²) for sorts of period (0,10,20,30,40min). During the exposure ,number and viability of LECs and MΦs on the surface of plates were observed. While in part two,TiO₂ treated plate and control plate were pre-irradiated by UVA (0.825 mw/cm²) for different time (0,20,40,60,80min).After the raying ,contact angle of each plate was measured, and the adherence of LECs and MΦs on the surface of plate were determined. In both two parts, the assay of MTT Colorimetric and Wright's staining were respectively used to estimated the number of LECs and MΦs, and Acridine Orange/Ethidium Bromide(AO-EB) staining as well as scanning electron microscope(SEM) were applied to observe the morphology of LECs and MΦs.Results In part one of the study , the number of LEC and MΦon TiO₂ membrane was inferior to control group significantly(P<0.01), While it was exposured to UVA with light intensity of 0.102mw/cm2 for 40min or 0.825mw/cm2 for 30min.At the same time, LEC showed the characteristic of apoptosis and necrosis by AO-EB staining, and MΦdisplayed the sign of cellular membrane rupture and disintegration in SEM. However, most of the cells on the surface of naked glass plate behaved normally under UVA raying. The longer TiO₂ thin film got irradiated , the fewer living cells on it were. And the lighthouse containing larger energy induced more predominance provocation to TiO₂ membrane.In part two of study, the contact angle of TiO₂ surface was smaller than control group, moreover the outcome approach 0o(1.78±0.47o)when TiO₂ membrane was pre-irradiated for 80min.After UVA pre-irradiation of 20min,the number of LEC and MΦdeposited on TiO₂ thin film was notably less than control plate(P<0.01). With the pre-irradiation time increased, cells sticked on TiO₂ nanometer thin film reduced and were devitalized.SEM observation presented that on the surface of plate with pre-irradiation of 80min, the adhered LECs on TiO₂ treated group were shrinked and MΦs drew back their filopodia, While the adhered cells on control group appeared active.Conclusion (1)TiO₂ nanometer thin films can produce the photocatalytic killing effect with UVA irradiation, and promote the apoptosis and necrosis of LEC and MΦon its surface.(2)The Photocatalytic Killing Effect of TiO₂ nanometer thin films is based on UVA raying ,and related to luminous intensity and exposure time.(3) After UVA pre-irradiation, TiO₂ surface possesses photoinduced superhydrophilicity for a period of time.(4)Activated by UVA pre-irradiation, TiO₂ nanometer thin films can reduce the adherence of LEC and MΦon its surface ever without UVA direct exposure.(5)TiO₂ nanometer thin films may be a kind of ideal material used for surface modified intraocular lens with improved biocompatibility.