BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 Vesicular biomineralization Biological vesicular mineralization Use of phospholipids structures to compartmentalize inorganic deposition Micrometer-sized droplets of supersaturated inorganic ions stabilized in oil by surfactant Nucleation and growth of inorganic phase occurs at surfactant headgroups, grows into microdroplet Igroups don't match perfectly to crystal Lipid mesophases provide mulitiple organized micro-and nano-structures for crystal deposition Characteristics of biological vesicular mineralization 1. Construction of enclosed, organized reaction environment a. Often using lipid bilayer vesicles b. Mineralization can occur inside or outside a boundary layer 2. Control of physicochemical conditions inside reaction environment via transmembrane ion channels transporters, and selective permeability 3. Control of nucleation kinetics 4. Production of complex crystal shapes by varying lipid matrix during growth Most common mi inerals produced by this method in biology: o Silica(SiO2)(amorphous)from Si(oH)4 silicic acid -algae and bacteria o Calcium carbonate(CaCO3) from CaHCO3 -algae and bacteria o Hydroxyapatite(calcium phosphate, Cas(OH)(PO4)3)from Ca and P04 human bone Vesicle reactors used in biology: phospholipids bilayers o Lipids have 2 hydrocarbon tails, so they can't pack into spherical micelles(molecules must have a shape complementary to this organization- wedge-shaped with big heads and'small tails o Form ubiquitous bilayer structure instead 柴 OOC Fig-5.1 Phospholipids IR and R are long-chain moieties. illustration of mesophases formed by lipid self- (a)micelle, (b) reverse micelle (c)lamella bilayer vesicle, (e)hexagonal,(f)inverse Lecture 11-Inorganic biomaterials 4of12BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 Lecture 11 – Inorganic Biomaterials 4 of 12 Vesicular biomineralization6 Biological vesicular mineralization • Use of phospholipids structures to compartmentalize inorganic deposition • Micrometer-sized droplets of supersaturated inorganic ions stabilized in oil by surfactant • Nucleation and growth of inorganic phase occurs at surfactant headgroups, grows into microdroplet • Nonspecific (non-epitaxial) growth- headgroups don’t match perfectly to crystal structure • Lipid mesophases provide mulitiple organized micro- and nano-structures for crystal deposition • Characteristics of biological vesicular mineralization: 1. Construction of enclosed, organized reaction environment a. Often using lipid bilayer vesicles b. Mineralization can occur inside or outside a boundary layer 2. Control of physicochemical conditions inside reaction environment via transmembrane ion channels, transporters, and selective permeability 3. Control of nucleation kinetics 4. Production of complex crystal shapes by varying lipid matrix during growth • Most common minerals produced by this method in biology: o Silica (SiO2) (amorphous) from Si(OH)4 silicic acid – algae and bacteria o Calcium carbonate (CaCO3) from CaHCO3 – algae and bacteria o Hydroxyapatite (calcium phosphate, Ca5(OH)(PO4)3) from Ca++ and PO4- - human bone • Vesicle reactors used in biology: phospholipids bilayers o Lipids have 2 hydrocarbon tails, so they can’t pack into spherical micelles (molecules must have a shape complementary to this organization- wedge-shaped with ‘big heads’ and ‘small tails’ o Form ubiquitous bilayer structure instead •