Biomaterials

Experimental results on the behavior of wetting on self-affine surfaces of natively oxidized Silicon (100) are presented. The self-affine surfaces have been prepared by the technique of ion irradiation. These surfaces, as results show, present hierarchical multi-scale rough morphologies, not observed earlier for hydrophilic surfaces. They further demonstrate a wetting behavior which  depends on the fractal dimension of the surface after irradiation. Results show that structural properties and fractal dimension of DNA molecules, immobilized on the self-affine surfaces, are effected by the fractal dimension and morphology of the surfaces prior to immobilization. The surfaces are self affine in nature and show hydrophilic behavior. The results presented here show that these surfaces exhibit multi- scale roughness with hierarchical structures. The wetting behavior of water droplets shows a dependence on the

fractal dimension of the surface after irradiation. Results on the Si/SiOx surfaces, after DNA immobilization, are also presented. The surfaces do not demonstrate any hierarchical roughness after immobilization and rather exhibit  two dimensional flat-smooth morphology. Modifications in the fractal dimension of DNA on these surfaces are also explored. Present studies can have technological implications for many bio-applications.