Espanol M, Perez R A, Montufar E B, Marichal C, Sacco A, Ginebra M P
Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, E08028 Barcelona, Spain.
Acta Biomater. 2009 Sep;5(7):2752-62. doi: 10.1016/j.actbio.2009.03.011. Epub 2009 Mar 17.
One key point in the field of tissue engineering and drug delivery is to provide materials with an adequate porosity. Many events, including nutrient and waste exchange in scaffolds for tissue engineering, as well as the drug-loading capacity and control of the release rate in drug delivery systems, are controlled by the size, shape and distribution of the pores in the material. Calcium phosphate cements (CPCs) possess an intrinsic porosity that is highly suited for these applications, and this porosity can be controlled by modifying some processing parameters. The objective of this work was to characterize and control the intrinsic porosity of alpha-tricalcium phosphate (alpha-TCP) cements, and to investigate its role against adsorption of bovine serum albumin (BSA). Cements with different percentages of open porosity (35-55%) were prepared by modifying the liquid-to-powder ratio. In addition, two different TCP particles were used to yield cements with specific surface areas of approximately 20 and approximately 37m(2)g(-1). Mercury porosimetry analysis on the set cements showed in most cases a bimodal pore size distribution which varied with the processing parameters and affected differently the adsorption and penetration of BSA. The peak occurring at larger pore dimensions controlled the penetration of BSA and was ascribed to the voids generated in between crystal aggregates, while the peak appearing at lower pore sizes was believed to be due to the intercrystallite voids within aggregates. It was found that, at the concentrations studied, the high intrinsic porosity in CPC does not ensure protein penetration unless there is an adequate pore size distribution.
组织工程和药物递送领域的一个关键点是提供具有适当孔隙率的材料。许多过程，包括组织工程支架中的营养物质和废物交换，以及药物递送系统中的药物负载能力和释放速率控制，都受材料中孔隙的大小、形状和分布的影响。磷酸钙骨水泥（CPC）具有非常适合这些应用的固有孔隙率，并且可以通过修改一些加工参数来控制这种孔隙率。这项工作的目的是表征和控制α-磷酸三钙（α-TCP）骨水泥的固有孔隙率，并研究其对牛血清白蛋白（BSA）吸附的作用。通过改变液粉比制备了具有不同开放孔隙率百分比（35 - 55%）的骨水泥。此外，使用了两种不同的TCP颗粒来制备比表面积约为20和约37m²g⁻¹的骨水泥。对凝固后的骨水泥进行压汞孔隙率分析表明，在大多数情况下，孔径分布呈双峰型，其随加工参数变化，对BSA的吸附和渗透有不同影响。出现在较大孔径处的峰值控制着BSA的渗透，这归因于晶体聚集体之间产生的空隙，而出现在较小孔径处的峰值据信是由于聚集体内的晶间空隙。研究发现，在所研究的浓度下，除非有合适的孔径分布，CPC中的高固有孔隙率并不能确保蛋白质渗透。
