<b><i>In‐vitro</i></b> preparation of nanocrystalline calcium phosphates as bone substitution materials in surgery

Tadic, D.; Veresov, A. G.; Putlayev, V.I.; Epple, Matthias

doi:10.1002/mawe.200300702

Cited by 22 publications

(12 citation statements)

References 6 publications

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“…Hence, it is commonly concluded that the material represents a calcium-deficient hydroxyapatite (CDHA). 3,9,26 The remaining mass of 11.9 wt% in the material is ascribed to water, hydroxide, and carbonate as shown by thermogravimetry. The TG curve showed a mass loss of 9.86 wt% up to 400°C due to water release and of 2.31 wt% between 400°C and 1000°C.…”

Section: Resultsmentioning

confidence: 99%

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A solid‐state NMR investigation of the structure of nanocrystalline hydroxyapatite

Jäger

Welzel

Meyer‐Zaika

et al. 2006

Magnetic Reson in Chemistry

328

420

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Nanocrystalline hydroxyapatite (HAp) prepared by a precipitation route was investigated. The X-ray diffraction (XRD) powder patterns of the elongated nanocrystals with a typical diameter of about 10 nm and length of 30-50 nm (by transmission electron microscopy (TEM)) revealed the presence of HAp with significantly broadened XRD reflections. However, Ca deficiency was found, as the Ca/P ratio was 1.5 only (so-called calcium-deficient hydroxyapatite (CDHA)), and not 1.67. This Ca deficiency of nanocrystalline HAp is explained using NMR. It is shown unambiguously that (i) the nanocrystals consist of a crystalline core and a (disordered) surface region with a relative phosphate content of about 1:1, (ii) the crystalline core is HAp, and (iii) the surface region is dominated by hydrogen phosphate anions (with no hydroxyapatite-like structural motif) and structural water (hydrate). From the relative phosphate content and taking into account the crystal shape, the thickness of the surface layer along the main crystal axis could be estimated to be about 1 nm, and the average chemical composition of the surface layer has been determined. Finally, a Ca/P ratio of 1.52 was estimated from the NMR data that compares well with the value of 1.51 from chemical analysis. The important consequences are that the surface of nanocrystalline HAp has nothing in common with the bulk composition and that the chemistry of such materials (e.g. the binding of protein molecules to phosphate surfaces) must be reconsidered.

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Section: Resultsmentioning

confidence: 99%

“…6,25,26 The sample studied here was precipitated at 70°C in a precipitation vessel with an average residence time of 420 s, but not under a nitrogen atmosphere so that a little carbon dioxide from the air was integrated as carbonate 27 into this sample, which will be discussed later in detail.…”

Section: Methodsmentioning

confidence: 99%

A solid‐state NMR investigation of the structure of nanocrystalline hydroxyapatite

Jäger

Welzel

Meyer‐Zaika

et al. 2006

Magnetic Reson in Chemistry

328

420

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“…However, still other preparation techniques are also known [31,45,147,154,275,355,. Continuous preparation procedures are also available [200,458]. Application of both ultrasound [362,[459][460][461] and viscous systems [462] might be helpful.…”

Section: Nanodimensional and Nanocrystalline Apatitesmentioning

confidence: 99%

Nanodimensional and Nanocrystalline Calcium Orthophosphates

Dorozhkin¹

2012

AJBE

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Nano-sized particles and crystals play an important role in the formation of calcified tissues of various animals. For example, nano-sized and nanocrystalline calcium orthophosphates in the form of apatites of biological origin represent the basic inorganic building blocks of bones and teeth of mammals. Namely, according the recent developments in biomineralization, tens to hundreds nanodimensional crystals of a biological apatite are self-assembled into these complex structures. This process occurs under a strict control by bioorganic matrixes. Furthermore, both a greater viability and a better proliferation of various types of cells have been detected on smaller crystals of calcium orthophosphates. Thus, the nano-sized and nanocrystalline forms of calcium orthophosphates have a great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This review reports on current state of the art and recent developments on the subject, starting from synthesis and characterization to biomedical and clinical applications. Furthermore, the review also discusses possible directions for future research and development.

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“…The obtained powder was immediately filtered off to avoid crystal growth and dried at 70 C. Details on the continuously working experimental setup can be found in Refs. [13][14][15].…”

Section: Methodsmentioning

confidence: 98%

Controlled release of gentamicin from biomimetic calcium phosphate in vitro. Comparison of four different incorporation methods

Tadic

Welzel

Seidel

et al. 2004

Materialwissenschaft Werkst

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Cylinders of biomimetic (nanocrystalline) calcium phosphate were loaded with gentamicin by four different methods: 1) dip-coating, 2) impregnation followed by cold-isostatic pressing, 3) co-precipitation followed by cold-isostatic pressing, and 4) coating of coprecipitated particles with a biodegradable polymer PDLLA (poly-D,L-lactide), followed by uniaxial pressing. The release kinetics were studied in vitro over 10 days. The incorporation by methods 2), 3) and 4) showed a significantly higher long-term release of active gentamicin than dip-coating, although there was an initial burst during the first two days with all four methods. With method 4), there was an increase of the released gentamicin after 7 days, and the long-term release was the highest of these four methods. The results are of considerable interest for the preparation of biodegradable bone implants which are loaded with biologically active substances.

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In‐vitro preparation of nanocrystalline calcium phosphates as bone substitution materials in surgery

Cited by 22 publications

References 6 publications

A solid‐state NMR investigation of the structure of nanocrystalline hydroxyapatite

A solid‐state NMR investigation of the structure of nanocrystalline hydroxyapatite

Nanodimensional and Nanocrystalline Calcium Orthophosphates

Controlled release of gentamicin from biomimetic calcium phosphate in vitro. Comparison of four different incorporation methods

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