Characterization of silica-coated hematite and application to the formation of composite particles including egg yolk PC liposomes

According to the method of Ohmori et al. (J. Colloid Interface Sci. 150 (1992) 594), a procedure is examined for the buildup of uniform silica layers on monodispersed hematite particles. It appears that the silica layer resulting is homogeneous and the layer thickness is controlled by the concentration of tetraethylorthosilicate (TEOS) in the medium. Further, egg PC liposomes, a typical biocolloid, are introduced onto the silica-coated hematite particle. The formation was proceeded by two types of processes: (1) heterocoagulation between the silica-coated hematite and egg PC liposomes by controlling the concentration of LaCl3 in the medium, or (2) buildup using two proteins (lysozyme or cytochrome C) as binder molecules. These results were analyzed by zeta-potential measurements and a contact-type X-ray microscope, which is a unique technique for obtaining X-ray images of biological specimens in water with high resolution. (C) 2003 Elsevier Inc. All rights reserved.