Structures Of Lecithin Vesicle And Its Controlling To Nano-Hydroxyapatite

In this paper, the vesicles of lecithin were prepared as a model of cellular membrane in bone biomineralization by ultrasonic method, and used for changing the reacting micro-environment of nano-hydroxyapatite (n-Hap) and for controlling the diameters and morphology of n-Hap crystals. By means of laser scattering spectrum and transmission electron microscopy (TEM), the effects of the acidity, temperature and inorganic ions in the solution on the diameters, shapes and stability of vesicles were studied. The results show that two kinds of vesicles were formed, One is smaller unilamellar vesicle (SUV) with mean diameters of 35-45 nm, and the other larger multilamellar vesicle (MLV) with mean diameters 180-320 nm. With the increase of ion concentration, the mean diameter of the vesicles increases, and the system becomes less stable. The effect of Ca2+ ions on the properties of vesicles is more complicated than that of Na+ ions. When the concentration of Ca2+ ions is between 0.02 mol/L and 0.06 mol/L, tube vesicles form in the solution. The mean diameter of vesicles is smaller and the vesicles are stable than that in other Ca2+concentration (below 0.02 mol/L or over 0.06 mol/L). In the different vesicles, the n-Hap formed has different sizes, morphology and dispersivity. When the Ca2+ concentration is 0.06 mol/L, the mean particle diameter of n-Haps is about 10 nm, and the shape is round and the particles are dispersed. Our results provide some useful inspiration in controlling particle sizes, shapes and structures of n-Haps or other inorganic particles by vesicles, and in understanding the bone biomineralization process.