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wfu2005

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[交流] 庆祝元旦分享一篇英国某大学的博士论文

Novel Phosphate Glasses for Bone Regeneration Applications

下载连接：http://www.brsbox.com/filebox/do ... 111b06a5010b6f46a12
http://www.brsbox.com/filebox/down/fc/98d469ebebc62111b06a5010b6f46a12

有用的话支持一下哦^_^

[ Last edited by wfu2005 on 2009-1-14 at 21:57 ]

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hslining

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Abstract

★ ★
amannnn(金币+2,VIP+0):谢谢版主介绍 4-20 08:14

Phosphate glass with additions of sodium, magnesium and/or calcium were investigated for their potential to be used as the reinforcing phase in a completely degradable long fibre composite. Glasses were prepared from phosphate salts as opposed to oxides and melted under air in platinum/gold crucibles. The effect of cation addition on the material properties and iocompatibility was investigated. Glasses were characterised using a number of complimentary techniques, including: XRD, XPS, DSC, IR and EDX. The findings from these techniques were used to explain the observed thermal and dissolution properties.

The thermal and dissolution properties were found to be dependant on both the thermal history and composition of the phosphate glass. For a hosphate glass with low cation content, the temperature and length of time held at that temperature increased the Tg by 10 °C for sodium phosphate glass and slightly improved the durability of sodium phosphate glass containing 10 mol.% MgHPO4, as phosphate chain growth was greater under those conditions. Addition of divalent cations increased the Tg of phosphate glasses from 295 °C for sodium phosphate glass by up to 150 °C with the addition of 50 mol.% MgHPO4. The dissolution rate was decreased exponentially with the addition of calcium phosphate or magnesium phosphate to sodium phosphate glass. Rates as low as 1x10-7 g cm-2 h-1 were achieved with the addition of 50 mol.% divalent cation phosphates. The divalent cations inhibited phosphate chain growth but formed a new network based upon divalent cation/non bridging oxygen cross-links. These cross-links were found to exert greater influence over the material properties then the phosphate chain length.

Cell culture assays were used to establish the biocompatibility of phosphate glasses with different compositions. Preliminary tests were conducted with craniofacial derived osteoblast like cells cultured on glass surfaces. Initial assays performed showed that the most durable glasses sustained the greatest amount of proliferation and differentiation over a seven day period. The most promising glass compositions, 40 Ca, 40 Mg, 30 Mg/20 Ca and 20 Mg/30 Ca, and were selected for longer term osteoblast culture and short term macrophage culture. Long term osteoblast culture showed that cells were able to attach, spread and proliferate throughout the 28 day duration of the study. Assays performed on the culture showed that cells were differentiating, producing specific osteoblast markers for each of the three differentiation phases of proliferation, matrix maturation and mineralisation. ECM production and mineralisation was confirmed on all surfaces tested via type I collagen staining and alizarin red staining respectively. Over the 28 day period, it was found that the composition did not have a significant effect on the production of the osteoblast markers, namely alkaline phosphatase, collagen, osteocalcin and mineral deposition. Immunological studies show that
macrophages are not activated by the presence of phosphate glass. This demonstrated that phosphate glass has shown potential for use a iomaterial.

[ Last edited by hslining on 2009-4-20 at 07:22 ]