Protein adsorption and monocyte activation on germanium nanopyramids

Germanium can Form defect-free pyramidal islands on Si(100)-2 x 1 with a he ight of 15 nm and a width of 60 nm. Using chemical vapor deposition we have prepared substrates with different nanopyramid densities to study the impa ct on contact angles, protein adsorption and cell behavior. The advancing c ontact angle of a water droplet of millimeter size significantly raises wit h nanopyramid density. The dynamic contact angle measurements reveal that t he substrate surface is highly hydrophilic. On such a surface the adsorptio n of hydrophilic proteins, i.e. albumin and globulin, is drastically increa sed by the presence of nanopyramids. More important. however, the globulin is inactive after adsorption on nanopyramid edges. This observation is supp orted by the cytokine release of IL-1 beta and TNF-alpha of monocyte-like c ell line U937. Consequently, the presence of nanopyramidal structures gives rise to less inflammatory reactions. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.