title: Fabrication and cytocompatibility of spherical magnesium ammonium phosphate granules.
abstract: Magnesium phosphate compounds, as for example struvite (MgNH4PO4·6H2O), have comparable characteristics to calcium phosphate bone substitutes, but degrade faster under physiological conditions. In the present work, we used a struvite forming calcium doped magnesium phosphate cement with the formulation Ca0.75Mg2.25(PO4)2 and an ammonium phosphate containing aqueous solution to produce round-shaped granules. For the fabrication of spherical granules, the cement paste was dispersed in a lipophilic liquid and stabilized by surfactants. The granules were characterized with respect to morphology, size distribution, phase composition, compressive strength, biocompatibility and solubility. In general, it was seen that small granules can hardly be produced by means of emulsification, when the raw material is a hydraulic paste, because long setting times promote coalescence of initially small unhardened cement droplets. Here, this problem was solved by using an aqueous solution containing both the secondary (NH4)2HPO4 and primary ammonium phosphates NH4H2PO4 to accelerate the setting reaction. This resulted in granules with 97 wt.% having a size in the range between 200 and 1,000 μm. The novel solution composition doubled the compressive strength of the cement to 37 ± 5 MPa without affecting either the conversion to struvite or the cytocompatibility using human fetal osteoblasts.
authors: Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany. Electronic address: theresa.christel@fmz.uni-wuerzburg.de.
authors: Theresa
authors: T
authors: Christel
authors: Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany. Electronic address: Martha.geffers@fmz.uni-wuerzburg.de.
authors: Martha
authors: M
authors: Geffers
authors: Department of Cranio-Maxillo-Facial Surgery, University of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany. Electronic address: klammert_u@klinik.uni-wuerzburg.
authors: Uwe
authors: U
authors: Klammert
authors: InnoTERE GmbH, Pharmapark Radebeul, Meissner Straße 191, 01455 Radebeul, Germany. Electronic address: berthold.nies@innotere.de.
authors: Berthold
authors: B
authors: Nies
authors: InnoTERE GmbH, Pharmapark Radebeul, Meissner Straße 191, 01455 Radebeul, Germany. Electronic address: andreas.hoess@innotere.de.
authors: Andreas
authors: A
authors: Höß
authors: Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany. Electronic address: juergen.groll@fmz.uni-wuerzburg.de.
authors: Jürgen
authors: J
authors: Groll
authors: Department of Cranio-Maxillo-Facial Surgery, University of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany. Electronic address: mkg@uni-wuerzburg.de.
authors: Alexander C
authors: AC
authors: Kübler
authors: Department for Functional Materials in Medicine and Dentistry, University of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany. Electronic address: uwe.gbureck@fmz.uni-wuerzburg.de.
authors: Uwe
authors: U
authors: Gbureck
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D019245:Compressive Strength; D004655:Emulsions; D006801:Humans; D006863:Hydrogen-Ion Concentration; D017616:Magnesium Compounds / Q000737:chemistry* / Q000493:pharmacokinetics / Q000633:toxicity; D008422:Materials Testing; D008863:Microspheres; D010316:Particle Size; D010710:Phosphates / Q000737:chemistry* / Q000493:pharmacokinetics / Q000633:toxicity; D000069877:Struvite
chemical_list: D004655:Emulsions; D017616:Magnesium Compounds; D010710:Phosphates; D000069877:Struvite
keywords: Calcium magnesium phosphate cement; Granules; Struvite