Creation of asymmetric bilayer membrane on monodispersed colloidal silica particles

Novel organic-inorganic nanohybrids, each having an inorganic core covered with an asymmetric lipid-bilayer membrane, were prepared through two-step self-assembling of a Cerasome-forming organoalkoxysilane lipid, N-[N-(3-triethoxysilyl)propylsuccinamoyl]-dihexadecylamine (1), as the inner layer with an appropriate bilayer-forming amphiphile, N,N-dihexadecyl-N-alpha-[6-(trimethylammonio)hexanoyl]alaninamide bromide (2), sodium N,N-dihexadecyl-N-alpha-(6-sulfohexanoyl)alaninamide (3), or dimyristoylphosphatidylcholine (DMPC; 4), as the outer layer on a monodispersed colloidal silica particle. The particle thus obtained was characterized by various physical measurements, such as FT-IR spectroscopy, transmission electron microscopy, differential scanning calorimetry, and zeta-potential measurements. These data strongly supported the successful formation of the asymmetric bilayer structure on the surface of the silica particle. The current method is widely applicable to various kinds of hybrids of inorganic particles with lipid membrane components. (C) 2004 Elsevier B.V. All rights reserved.