Studies On Preparation And Properties Of Silk Fibroin/Calcium Phosphate/Calcium Sulfate Composites

In this paper, the SF/CPC/CSH composites which have good injectablity and canbe solidified and form pores in situ was prepared, this composites composed of thecalcium phosphate cement (CPC) and the silk fibroin particle (SFP) microspheres whichwas mainly amorphous structure. The influence of the proportion of SFP, the proportionof calcium sulfate hemihydrate (CSH) and liquid to powder (L/P) ratio on the structureand properties of composites were studied, and the change of structure and properties ofsamples when immersed in SBF were investigated. The results showed that the SFwhich had the morphology of a hollow sphere was prepared, and the aggregationstructure of the SFP was mainly the amorphous. The SFP could form obvious pores incomposites, the number and the largest pore size of pores had increased trend with theincreased proportion of SFP. The size of pore which was formed by SFP ranged from15.2μm to284.6μm. The composites which had5%of SFP and10%of CSH wereprepared by the L/P ratio greater than or equal to0.45ml/g, and the average size of thepores in these composites had not significant difference, but all larger than the averagesize of pores in the composites which prepared by the L/P ratio to0.40ml/g. Theproportion of CSH had no significant effect on the number and size of pores incomposites.The composites started up setting reaction and transformed into HA in seven weeks.The dicalcium phosphate anhydrous transformed into HA in the first week, but thetetracalcium phosphate was not totally transformed and still contained after seven weeks.The surface of composites which had different proportion of SFP all had platelet-likeand needle-like HA crystals. The surface of composites which had different ratio ofCSH all were mainly needle-like HA crystals. The surface of composites which had5%of SFP and10%of CSH were mainly rod-like HA crystals when this compositesprepared by the L/P ratio to0.40ml/g, and the surface of the composites were mainlyneedle-like HA crystals when prepared by the L/P ratio to0.45ml/g and0.50ml/g, andthe surface of composites were mainly platelet-like HA crystals when prepared by theL/P ratio to0.50ml/g. The average porosity of composites which contained SFP was larger than53%, andthe average porosity of the pure CPC was46.8%. The porosity had increased from49.3%to59.4%with the increased proportion of SFP when the proportion was less than5%, but the porosity had decreased trend with the increased proportion of SF when theproportion was higher than5%. The porosity had increased from55.7%to61.6%withthe increased proportion of CSH from0%to30%of the composites.The porosity hadincreased trend with the increased L/P ratio.The compressive strength and work-of-compressive of composites had increasedtrend with the increased proportion of SFP, but had decreased trend with the increasedproportion of CSH or the increased L/P ratio.Under the L/P ratio conditions of this experiment, there had no significantdifferences of setting time and injectability between the composites which had differentSF proportion and the composites which had different CSH proportion. All setting timeof composites were within the range of13min to16min, and all the injection rate wereabove90%. The L/P ratio had a significant effect on the setting time and injection ratioof composites, the setting time extended and the injection rate increased with increasedof the L/P ratio, and the injection rate of composites increased from44.9%to84.3%when the L/P ratio increased from0.40ml/g to0.45ml/g.The weight of CPC and SFP/CPC composites had increased trend when thesamples immersed in SBF in five weeks. The weight of composites which containedCSH had decreased trend when the composites immersed in SBF in three weeks, but theweight had slightly increased from the third week to the fifth week, and the weight haddecreased trend after five weeks. The pores of pure CPC had not significant changesand still dense when the composites immersed in SBF. The surface of composites whichhad10%of CSH appeared more and more microporous with time extended when thecomposites immersed in SBF. The composites which contained SFP and CSH becomesomewhat loose with time extended when the composites immersed in SBF, The surfacemorphology of composites which without CSH had no significant difference with timeextended when the composites immersed in SBF.