BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 Example: radiolarian skeleton o Silica-skeleton algae >1 mM Silic Fig- 2.18 The chemical nature of amorphous silica nucleated at exterior surface of icro-skeleton. Scale bar, 10 um. I rr ⊙ Stages in the morphogenesis of the diatom frustule, See text for details. SDV-silica deposition vesicles AV- aleolar vesicle PL-plasmalemma(lipid bilayer cell wall) ER-endoplasmic reticulum Example: human bone formation o Growth plate cartilage, tooth dentine(Clin. Orth. Re R 314, 266(1995)) 1. Matrix vesicles 100-200 nm diameter secreted. attach to matrix 2. Calcium and phosphate ions influx into vesicle nanoreactors 3. Calcium phophate supersaturate 4. Controlled precipitation in amorphous structure 5. Crystallizes into hydroxyapatite 6. Growing crystals burst vesicles 7. Growth continues, controlled by extracellular conditions Lecture 11-Inorganic biomaterials 6of12BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 Lecture 11 – Inorganic Biomaterials 6 of 12 • Example: radiolarian skeleton7 o Silica-skeleton algae Si(OH)4 Silicic acid > 1 mM Mineralization nucleated at exterior surface of vesicles Ôvesicle foamÕ SDV - silica deposition vesicles AV - aleolar vesicles PL - plasmalemma (lipid bilayer cell wall) ER - endoplasmic reticulum nanovesicles • Example: human bone formation o Growth plate cartilage, tooth dentine (Clin. Orth. Re. R 314, 266 (1995)) 1. Matrix vesicles 100-200 nm diameter secreted, attach to matrix 2. Calcium and phosphate ions influx into vesicle nanoreactors 3. Calcium phophate supersaturates 4. Controlled precipitation in amorphous structure 5. Crystallizes into hydroxyapatite 6. Growing crystals burst vesicles 7. Growth continues, controlled by extracellular conditions