RESUMO
The rates of adhesion of melanoma cells (carcinogenic) onto nonionic polymer surfaces were studied by using radioactively labeled cells and measuring the fraction of cells which adhered to the surface in a given time. Glow discharge (plasma) polymerization of 1,1,3,3-tetramethyldisiloxane and of nitrogen-acetylene-water (mole ratio 0.4:1.0:0.2) was used to modify the surface energy of the substrate. The cell adhesion rate was found to be given by Y = 1 - exp [-k0(gammas - gamma0)t], where Y is the fraction of cells adhered, -k0 is a characteristic rate constant, gammas is the total surface energy of the substrate, gamma0 is the threshold surface energy of cell adhesion, and t is time.
Assuntos
Adesão Celular , Técnicas Citológicas , Melanoma/patologia , Polímeros , Humanos , Técnicas In Vitro , Propriedades de SuperfícieRESUMO
The corneal polarization cross can be seen at the human cornea using crossed polaroids. The optical mechanisms for this phenomena include rotation and retardation of the light at the surface of the cornea due to the corneal curvature, as well as retardation due to an average circumferential orientation of the birefringent corneal collagen.
Assuntos
Córnea/fisiologia , Polarografia , Birrefringência , Humanos , Rotação OcularRESUMO
Plasma coating (deposition of polymer under the influence of plasma) is utilized to modify the surface properties of corneal contact lens. An ultrathin layer (thickness of roughly 200 A) of plasma polymer of acetylene/H20/N2 is applied to poly(methyl methacrylate) (PMMA) corneal contact lenses. The surface becomes highly wettable with water compared to uncoated lens. When coated and uncoated contact lenses are placed on rabbit eyes, a remarkable difference in accumulation of mucous matter is observed. With the control lenses, the accumulation of mucous matter in a week is sufficient to affect the optical clarity of the lenses, whereas the coated lenses show no change after three months continuous wearing. The comparative degree of adhesion of the corneal epithelium cells onto glass, modified glass, PMMA, and coated PMMA surfaces is studied using tissue cultures and phase contrast microscopy. The coated PMMA surface exhibits a degree of tissue adhesion lower than that of control PMMA and higher than that of glass surface, and no sign of toxicity of the coated surface is observed by the tissue cultures.