文档介绍:Molecular Principles of Biomaterials Spring 2003
Lecture 12: Organic templating of anic materials and bone biomimesis
Last time: interfacial biomineralization and biomimetic anic chemistry
Today: biological strategies for anic templating anic materials
anic template materials
Biomimesis of bone
Reading: S. Mann, ‘Biomineralization: Principles and Concepts of anic Materials
Chemistry,’ Ch. 6, pp. 89-124 (2001)
Biological strategies for anic templating anic materials
Alteration of barriers to nucleation
• Organic surfaces alter free energy barrier to nucleation (Mann Science 1993)
∆G*
∆Gnuc
o Reminder of free energy of nucleation (homogeneous, but principle applies to heterogeneous surface
nucleation as well):
2 4 3 ∆Gv
∆Gnuc =∆Gsurface −∆Gbulk = 4πr σ−πr
3 Vm
Where ∆Gv is the free energy change for formation of the solid per mole from the ions, and Vm is the
molar volume of the nucleated solid
Lecture 12 – anic Biomaterials 1 of 13
Molecular Principles of Biomaterials Spring 2003
• How are free energy barriers modified anic templates? (Mann 1993) Complementarity in:
1. Surface lattice geometries
2. Spatial charge distributions
3. Polarity of hydration layers
4. Defect sites
5. Bonding chemistry
Coordination environment of metal ion in crystal mimicked by binding anic surface groups
o Matching lattice geometries:
Organic templating layer
New crystal
(Mann et al. 1993)
o Matching charge distributions:
Case of calcium cabonate: different crystal structures and crystal orientations nucleated on different
charge surfaces
Lecture 12 – anic Biomaterials 2 of 13
Molecular Principles of Biomaterials Spring 2003
o Templates used by nature:
Proteins
Lipids
harides
o Process is universal for templated nucleation:
Material: carbonates, phosphates silica, ice
Template: carboxy-rich moieties hydrogen-bonding