Biomimetic mineralization

One of the important fields where carbohydrate polymer/inorganic hybrids may be successfully applied is bioactive materials, e.g., artificial bones expedient for surgery to accelerate the recovery of living bones. There has been increasing interest in hydroxyapatite (HAp) deposition onto the matrix surface of cellulose or related polysaccharide. HAp is a form of calcium phosphate, a main constituent of the inorganic phase of human bone. This kind of study is also a step on the way to exploitation of new biomimetic mineralization methods. 

Wang B et al (2008) Yeast cells with an artificial mineral shell protection and modification of living cells by biomimetic mineralization. Angew Chem Int Ed Engl 47 3560-3564... 

Bradt JH, Mertig M, Teresiak A, Pompe W (1999) Biomimetic mineralization of collagen by combined fibril assembly and calcium phosphate formation. Chem Mater 11(10) 2694—2701... 

Ethirajan A, Ziener U, Landfester K (2009) Surface-functionalized polymeric nanoparticles as templates for biomimetic mineralization of hydroxyapatite. Chem Mater 21(11) 2218-2225... 

Biomimetic mineralization of aqueous carbonate ions into chitosan-calcium alginate hydrogels... 

Planar polymer films were recently mineralized with calcium phosphate [267], Using the Langmuir monolayer technique, it was possible to control the particle growth by the polymer film properties at the air-water interface and the subphase parameters (pH, ion strength). Small changes it the growth conditions resulted in various particle shapes and dimensions. Such examples of controlled biomimetic mineralization are indeed very motivating for further studies of crystallization processes in synthetic membranes. 

An example from chemistry is the use of vesicles, liquids, and foams to direct biomimetic mineralization and polymerization. Such templates, that may only have a transitory existence were used to template the assembly of structurally complex, three-dimensional architectures. Subsequently, within supramolecular chemistry, the term "direeted self-assembly" has become more generally understood to include any templated process that brings together molecular components, even if the directing moiety is part of the final structure. " ... 

Mata A, Geng Y, Henrikson KJ, Aparicio C, Stock SR, Satcher RL, Stupp SI (2010) Bone regeneration mediated by biomimetic mineralization of a nanofiber matrix. Biomaterials 31 6004-6012. doi 10.1016/j.biomaterials.2010.04.013... 

The use of double hydrophilic block copolymers in biomimetic mineralization processes has been investigated in recent years. In contrast to rigid templates (like carbon nanotubes and porous aluminum templates which predefine the final structure) water soluble polymers could be used as soluble species at various hierarchy levels. Usually, in the case of DHBCs, one of the block acts as scaffold for the development of the crystal, while the other acts as a soluble-stabilizing matrix. Therefore, both of the blocks play a crucial role on the development of the crystals. There is a plethora of reports on the emerging bio-inspired mineralization field. Various crystal structures have been presented during the last years, following versatile synthetic routes. A very detailed and illustrious review has been recently given by Colfen [3]. The above review describes in detail all aspects of the specific field. Herein, we present just a few selected examples. 

Figure 4.1 Synthesis of bone-like composites through a biomimetic strategy inspired from bone biomineralization, (a) Biomimetic composites were obtained by first cross-linking maleic chitosan with PEGDA under UV light in water to form 3-D hydrogel networks, followed by biomimetic mineralization Images of maleic chitosan/PEGDA hydrogel (b) before and (c) after mineralization.

Figure 4.2 Self-assembling peptide amphiphiles (PA) used for biomimetic mineralization of HA/PA nanocomposite, (a) Chemical structure of the PA, comprising 5 regions (1) a hydrophobic alkyl tail (2) four cysteine residues that can form disulfide bonds to polymerize the self-assembled structure (3) a flexible linker region of three glycine residues (4) a single phosphorylated serine residue that was able to interact strongly with calcium ions and help direct mineralization of HA (5) the cell adhesion ligand ROD. (b) Molecular model of one single PA molecule, (c) Schematic showing the self-assembly of PA molecules into a cylindrical micelle.

In addition to promoting periodontal tissue regeneration, a study published in 2014 has shown that EMD promoted in vitro biomimetic mineralization and facilitated enamel prism-like tissue formation on demineralized human enamel. Thus, using EMD in biomimetic mineralization may serve as a biomaterial for enamel repair (Cao et al., 2014). So far, several brands based on EMD have been marketed the first to be commercially available of those is Emdogain. 

Cardoso, M.B., Luckarift, H.R., Urban, V.S., O Neill, H., and Johnson, G.R. 2010. Protein localization in silica nanospheres derived via biomimetic mineralization. Adv. Fund. Mater. 20 3031-3038. 

Bernhardt et al. [234] obtained a synthetic material that mimics the composition and structure of the extracellular bone matrix, which mainly consists of Coll fibrils, mineralized with HAp (nano)crystals. This nanocomposite material was produced in a biomimetic process, in which Col fibril assembly and mineralization with HAp occur simultaneously. The authors observed that the membranes from biomimetically mineralized Coll show a substantial influence on the osteogenic differentiation of human bone-marrow-derived stromal cells (hBMSCs). The bone-like composition of the material, combined with its stimulating effect on the osteogenic differentiation of hBMSC, makes it appropriate for human bone regeneration. 

Petrauskaite O, Gomes PDS, Fernandes MH, Juodzbalys G, Stumbras A, Maminskas J, et al. Biomimetic mineralization on a macroporous cellulose-based matrix for bone regeneration. Biomed Res Int 2013 2013. [online]. 

Jiang Y, Yang D, Zhang L, Sun Q, Sun X, Li J, Jiang Z. Preparation of protamine-titania microcapsules through synergy between layer-by-layer assembly and biomimetic mineralization. Adv Funct Mater 2009 19 150-156. 

Polymer-Controlled Biomimetic Mineralization of Novel Inorganic Materials... 

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