Wei Guobao, Ma Peter X
Department of Biomedical Engineering, University of Michigan, Ann Arbor, 48109-2209, USA.
J Biomed Mater Res A. 2006 Aug;78(2):306-15. doi: 10.1002/jbm.a.30704.
Scaffolds are crucial to tissue engineering/regeneration. In this work, a technique combining a unique phase-separation process with a novel sugar sphere template leaching process has been developed to produce three-dimensional scaffolds. The resulting scaffolds possess high porosities, well connected macropores, and nanofibrous pore walls. The technique advantageously controls macropore shape and size by sugar spheres, interpore opening size by assembly conditions (time and temperature of heat treatment), and pore wall morphology by phase-separation parameters. The bioactivity of a macroporous and nanofibrous poly(L-lactic acid) (PLLA) scaffold was demonstrated by the bone-like apatite deposition throughout the scaffold in a simulated body fluid (SBF). Preincorporation of nanosized hydroxyapatite eliminated the induction period and facilitated the apatite growth in the SBF. Interestingly, the apatite growth primarily occurred on the surface of the pores (internal and external) but not the interior of the nanofibrous network away from the pore surface. It was also noticed that the macropore size did not affect the apatite growth rate, while the interpore opening size did. The compressive modulus also increased substantially when a continuous apatite layer was formed on the pore walls of the scaffold. The resulting composite scaffold mimics natural bone matrix with the combination of an organic phase (a polymer such as PLLA) and an inorganic apatite phase. The demonstrated bioactivity of apatite layer, together with well-controlled macroporous and nanofibrous structures, makes the novel nanocomposite scaffolds desirable for bone tissue engineering.
支架对于组织工程/再生至关重要。在这项工作中，已开发出一种将独特的相分离过程与新颖的糖球模板浸出过程相结合的技术来制备三维支架。所得支架具有高孔隙率、连通性良好的大孔和纳米纤维孔壁。该技术通过糖球有利地控制大孔的形状和尺寸，通过组装条件（热处理时间和温度）控制孔间开口尺寸，并通过相分离参数控制孔壁形态。在模拟体液（SBF）中，通过在整个支架中沉积类骨磷灰石证明了大孔和纳米纤维聚（L-乳酸）（PLLA）支架的生物活性。预掺入纳米级羟基磷灰石消除了诱导期并促进了SBF中磷灰石的生长。有趣的是，磷灰石生长主要发生在孔（内部和外部）的表面，而不是远离孔表面的纳米纤维网络内部。还注意到，大孔尺寸不影响磷灰石的生长速率，而孔间开口尺寸则有影响。当在支架的孔壁上形成连续的磷灰石层时，压缩模量也大幅增加。所得的复合支架通过有机相（如PLLA等聚合物）和无机磷灰石相的组合模拟天然骨基质。磷灰石层所展示的生物活性，连同得到良好控制的大孔和纳米纤维结构，使得这种新型纳米复合支架成为骨组织工程的理想选择。
