Fabrication and Characterization of Porous Calcium Polyphosphate Scaffolds
Department of Polymer Science, Sichuan University, Hua-yang, Sichuan, China Journal of Materials Science
(Impact Factor: 2.37).
04/2006; 41(8):2429-2434. DOI: 10.1007/s10853-006-5182-2
Porous calcium polyphosphate (CPP) scaffolds with different polymerization degree and crystalline phases were prepared, and
then analyzed by scanning electron microscopy (SEM), Thermmogravimetry (TG) and X-ray diffraction (XRD). Number average polymerization
degree was calculated by analyzing the calcining process of raw material Ca(H2PO4)2, as a polycondensation reaction. Amorphous CPP were prepared by the quenching from the melt of Ca(H2PO4)2 after calcining, and CPP with different polymerization degree was prepared by controlling the calcining time. Meanwhile,
CPP with the same polymerization degree was prepared to amorphous or different crystalline phases CPP which was made from
crystallization of amorphous CPP. In vitro degradation studies using 0.1 M of tris-buffered solution were performed to assess the effect of polymerization degree or
crystalline phases on mechanical properties and weight loss of the samples. With the increase of polymerization degree, the
weight loss during the degradation decreased, contrarily the strength of CPP increased. The degradation velocity of amorphous
CPP, α-CPP, β-CPP and γ-CPP with the same polymerization degree decreased in turn at the same period. The full weight loss
period of CPP can be controlled between 17 days and more than 1 year. The results of this study suggest that CPP ceramics
have potential applications for bone tissue engineering.
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ABSTRACT: This work is concerned with the finite element modeling of a dual-porous scaffold including both fine and coarse pores. The layer with coarse pores is suitable for bone in vivo ingrowth and the finer pore layer is appropriate for in vitro cartilage culturing. Such scaffolds can be extensively used for repairing of osteochondral defects. The bio-mechanical properties of the proposed scaffold, including apparent stiffness and strain-based capability of the cell ingrowth, are identified using a 3D Finite Element Model. Moreover, to study the effect of the second layer on the strength of the whole scaffold, the stiffness of the dual and single-porous scaffolds was compared. The result of this study shows that the stiffness decreases by adding the second layer to a single-porous scaffold. Additionally, principal strain histograms of the single and the dual-porous scaffolds are compared to assess the effect of added layer on the capability for cell ingrowth stimulation of the whole structure. According to the results, the dual-porous scaffold provides more homogeneous distribution but a smaller amount of micro-strains which may cause different cell-growth behavior.
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ABSTRACT: Preparation, characterization and in vitro study of a series of calcium polyphosphate (CPP) with different polymerization degree were reported. A series of CPP with different polymerization degree were prepared by controlling calcining time. Average polymerization degree was analyzed by liquid state 31P nuclear magnetic resonance (NMR). The microstructure was observed by scanning electric microscope (SEM). X-ray diffraction (XRD) analysis was used to demonstrate that polymerization degree would not affect the crystal system and space group of CPP. The results showed that polymerization degree increased with the increase of calcining time. Degradation studies were performed during 32 days in physiological saline solution (aqueous solution, 0.9 wt.%NaCl) to assess the effect of polymerization degree on the degradation velocity of the samples. It was also shown that the degradation velocity of CPP (polymerization degree=13) doubles than another two samples (polymerization degree=9,19). The results in the present study may be able to provide some fundamental data for controlling CPP degradation.
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