Possible model of protein nucleation and crystallization on porous silicon

The problem of macromolecular nucleation and crystallization on porous silicon surface is investigated theoretically. The fractality of the porous silicon layer is exploited. It is shown that the effective surface density of adsorbed particles on a fractal self-similar surface significantly exceeds that on a flat surface. The resulting local supersaturation explains enhanced nucleation phenomena associated with porous silicon. In addition, the self-affine fractal surface exhibits quasi-periodicity that can facilitate long-range ordering of the nucleated molecules, i.e. the crystallization process. Moreover, small elastic constants of porous silicon are favorable for the surface periodicity tuning to different lattice parameters of growing crystals. The anomalous large scaling range (from silicon interatomic distance up to 100 nm) is favorable for the crystallization of wide range of big macromolecules such as proteins. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.