[Viability of murine 3T3 fibroblasts on the poly(methyl methacrylate) surface modified by constant UV irradiation]

Poly(methyl methacrylate) (PMMA) is commonly applied both in dentistry (bone cement) and in ophthalmology (contact lens, intraocular implants). High adhesion of fibroblasts to bone cement is desirable but keratoprosthesis (intraocular lens--IOL) should be characterized by good transparency and indicate no cells adhesion. Some earlier reports show that sterilization and modification of surface properties of some polymers can be achieved by UV-irradiation which causes a serious physicochemical change in polymer materials to depth of 4 microm. In present studies the surface of PMMA films (30 microm) was continuously irradiated with monochromatic UV-light at 254 nm in varied time intervals. The viability of murine 3T3 fibroblasts cultivated by 12 hours on the surfaces of the non-exposed and the UV-irradiated PMMA in relation to the control fibroblast cell line cultured on the surface of borosilicate glass was estimated with standard fluorescence microscopy procedure. It was found, that 3T3 fibroblasts are highly sensitive to the chemical changes of irradiated surface of PMMA, i.e. increase of surface hydrophilicity and oxidation degree accompanied by decrease of polymer molecular mass and increase of free monomer fraction as determined on the results of contact angle measurements and attenuated total reflection infrared spectra. The percentage of living 3T3 fibroblast cells was 87% after cultivation on the untreated virgine PMMA and only 47% after cultivation on the polymer which was pre-irradiated by 72 h. No further changes in fibroblasts viability (47%) was observed in cultures developed on PMMA after 96 h of its introductory permanent irradiation. However, a period of 48 h of such constant UV-irradiation was quite optimal to obtain a specific modification of PMMA surface leading to significantly increased viability of cultured 3T3 fibroblasts up to the 94%.