Biomimetic Hydroxyapatite Crystallization in Gelatin Nanoparticles Synthesized Using a Miniemulsion Process

Ethirajan, Anitha; Ziener, Ulrich; Chuvilin, Andrey; Kaiser, Ute; Cölfen, Helmut; Landfester, Katharina

doi:10.1002/adfm.200800048

Cited by 80 publications

(62 citation statements)

References 51 publications

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“…45 and also in the complete absence of soluble additives, using reaction solutions containing very high concentrations of calcium and phosphate. 38 With a further decrease in the surface separation to SS  0.5 µm, nanospheres were observed alongside the platelets (Figure 3b).…”

Section: Methodsmentioning

confidence: 99%

Confinement Increases the Lifetimes of Hydroxyapatite Precursors

2014

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The mineral component of bone is a carbonated, non-stoichiometric hydroxyapatite (calcium phosphate) that forms in nanometer confinement within collagen fibrils, the principal organic constituent of bone. We here employ a model system to study the effect of confinement on hydroxyapatite precipitation from solution under physiological conditions. In common with earlier studies of calcium carbonate and calcium sulfate precipitation, we find that confinement significantly prolongs the lifetime of metastable phases, here amorphous calcium phosphate (ACP) and octacalcium phosphate (OCP). The effect occurs at surprisingly large separations of up to 1 m, and at 0.2 m the lifetime of ACP is extended by at least an order of magnitude. The soluble additive poly(aspartic acid), which in bulk stabilizes ACP, appears to act synergistically with confinement to give a greatly enhanced stability of ACP. The reason for the extended lifetime appears to be different from that found with CaCO 3 and CaSO 4 , and underscores both the variety of mechanisms whereby 2 confinement affects the growth and transformation of solid phases, and the necessity to study a wide range of crystalline systems to build a full understanding of confinement effects. We suggest that in the case of ACP and OCP the extended lifetime of these metastable phases is chiefly due to a slower transport of ions between a dissolving metastable phase, and the more stable, growing phase. These results highlight the potential importance of confinement on biomineralisation processes.3

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Section: Methodsmentioning

confidence: 99%

Confinement Increases the Lifetimes of Hydroxyapatite Precursors

2014

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“…Looking specifically at the effects of confinement on CaP precipitation, sequential transformation of ACP to HAP through octacalcium phosphate (OCP) has been observed within the confines of crosslinked gelatine nanoparticles. [12] Further, preferential alignment of HAP crystals has been observed within uniaxially deformed gelatine films, [13] and in bundles of nanofibres, [14] in which the [001] axis of HAP showed preferential alignment with the long axes of the fibres.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Confinement Controls the Crystallization of Calcium Phosphate: Relevance to Bone Formation

Cantaert

Beniash

Meldrum

2013

Chemistry A European J

101

124

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A key feature of biomineralization processes is that they take place within confined volumes, in which the local environment can have significant effects on mineral formation. Herein, we investigate the influence of confinement on the formation mechanism and structure of calcium phosphate (CaP). This is of particular relevance to the formation of dentine and bone, structures of which are based on highly mineralized collagen fibrils. CaP was precipitated within 25–300 nm diameter, cylindrical pores of track etched and anodised alumina membranes under physiological conditions, in which this system enables systematic study of the effects of the pore size in the absence of a structural match between the matrix and the growing crystals. Our results show that the main products were polycrystalline hydroxapatite (HAP) rods, together with some single crystal octacalcium phosphate (OCP) rods. Notably, we demonstrate that these were generated though an intermediate amorphous calcium phosphate (ACP) phase, and that ACP is significantly stabilised in confinement. This effect may have significance to the mineralization of bone, which can occur through a transient ACP phase. We also show that orientation of the HAP comparable, or even superior to that seen in bone can be achieved through confinement effects alone. Although this simple experimental system cannot be considered, a direct mimic of the in vivo formation of ultrathin HAP platelets within collagen fibrils, our results show that the effects of physical confinement should not be neglected when considering the mechanisms of formation of structures, such as bones and teeth.

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“…Recently, in our group gelatin nanoparticles and surface-functionalized polymer nanoparticles were employed for the biomimetic mineralization of HAP. [26,27] The synthesis of biodegradable particles in a sub-mm range by a combination of the solvent evaporation and the miniemulsion technique has been recently reported. [28] Interestingly, the nanoparticles synthesized via miniemulsion have added advantage for this application for the following reasons: As mentioned before, although the primary mechanism of degradation of these aliphatic polyesters occur via hydrolysis of backbone ester groups, it is necessary to consider the degradation occurring during the ultrasonication step throughout the miniemulsion formation.…”

Section: Introductionmentioning

confidence: 99%

Biodegradable Polymeric Nanoparticles as Templates for Biomimetic Mineralization of Calcium Phosphate

Ethirajan

Musyanovych

Landfester

2011

Macro Chemistry & Physics

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Biodegradable polymeric nanoparticles are employed as templates for the biomimetic mineralization of CaP in the aqueous phase. Particles in the sub‐µm range were prepared by a combination of solvent evaporation and miniemulsion techniques. The synthesized particles were subjected to degradation via random saponification. The anionic functional groups produced as a consequence of degradation due to production (ultrasonication step) and post treatment (hydrolysis) steps are used for the CaP mineralization. The composite particles were studied using HRSEM, TEM, and XRD. These polymer/CaP composite nanoparticles have a great potential to be used as a regenerative filler or as a scaffold for nucleation and growth of new bone material.

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Biomimetic Hydroxyapatite Crystallization in Gelatin Nanoparticles Synthesized Using a Miniemulsion Process

Cited by 80 publications

References 51 publications

Confinement Increases the Lifetimes of Hydroxyapatite Precursors

Confinement Increases the Lifetimes of Hydroxyapatite Precursors

Nanoscale Confinement Controls the Crystallization of Calcium Phosphate: Relevance to Bone Formation

Biodegradable Polymeric Nanoparticles as Templates for Biomimetic Mineralization of Calcium Phosphate

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