Department of Materials Science and Engineering, The University of Tennessee, Knoxville, 37996, USA.
Acta Biomater. 2011 May;7(5):2185-99. doi: 10.1016/j.actbio.2011.01.034. Epub 2011 Feb 1.
We present a systematic study for investigating the role of exposed hydroxyapatite (HA) nanoparticles in influencing surface characteristics and mouse pre-osteoblastic MC3T3-E1 cell behavior using nanocomposites prepared by photo-crosslinking poly(ε-caprolactone) diacrylate (PCLDA) with HA. PCLDA530 and PCLDA2000 synthesized from poly(ε-caprolactone) diol precursors with nominal molecular weights of 530 and 2000 g mol(-1) were used as the polymer matrices. Crosslinked PCLDA530 was amorphous while crosslinked PCLDA2000 was semi-crystalline. Crosslinked PCLDA/HA composites with different compositions of HA (10%, 20% and 30%) as well as crosslinked PCLDAs were characterized in terms of their composition-dependent physicochemical properties. The tensile, compressive and shear moduli were greatly enhanced by incorporating HA nanoparticles with the polymer matrices. The disk surfaces of original crosslinked PCLDA/HA nanocomposites were removed by cutting using a blade to expose HA nanoparticles that were embedded in the polymer substrates. The composition of HA was much higher on the cut surface, particularly in semi-crystalline crosslinked PCLDA2000/HA nanocomposites. The surface characteristics of original and cut crosslinked PCLDA/HA nanocomposites were compared and correlated with cell behavior on these nanocomposites. MC3T3-E1 cell attachment, proliferation and differentiation were significantly enhanced when the HA composition was increased in original crosslinked PCLDA/HA nanocomposites due to more bioactive HA, higher surface stiffness and rougher topography. More exposed HA on the surface of cut semi-crystalline PCLDA2000/HA nanocomposites resulted in improved hydrophilicity and significantly better MC3T3 cell attachment, proliferation and differentiation compared with the original surfaces. This study suggests that HA nanoparticles may not be fully exploited in polymer/HA nanocomposites where the top polymer surface covers the particles. The removal of this polymer layer can generate more desirable surfaces and osteoconductivity for bone repair and regeneration.
我们进行了一项系统研究，通过光交联聚己内酯二丙烯酸酯（PCLDA）与羟基磷灰石（HA）制备纳米复合材料，来研究暴露的羟基磷灰石（HA）纳米粒子在影响表面特性和小鼠前成骨 MC3T3-E1 细胞行为方面的作用。使用两种不同相对分子质量的聚己内酯二醇（PCL）为起始原料合成了 PCLDA530 和 PCLDA2000，它们的标称相对分子质量分别为 530 和 2000 g/mol。交联的 PCLDA530 为无定形，而交联的 PCLDA2000 为半结晶。研究了不同 HA 含量（10%、20%和 30%）的交联 PCLDA/HA 复合材料以及交联 PCLDA 的组成依赖性物理化学性质。通过将 HA 纳米粒子与聚合物基质复合，大大提高了拉伸、压缩和剪切模量。用刀片切割原始交联 PCLDA/HA 纳米复合材料的圆盘表面，去除圆盘表面的聚合物，暴露出嵌入聚合物基底的 HA 纳米粒子。在切割表面上的 HA 组成要高得多，特别是在半结晶交联 PCLDA2000/HA 纳米复合材料中。比较了原始和切割交联 PCLDA/HA 纳米复合材料的表面特性，并将其与这些纳米复合材料上的细胞行为相关联。由于具有更高的生物活性 HA、更高的表面硬度和更粗糙的形貌，原始交联 PCLDA/HA 纳米复合材料中 HA 含量的增加显著促进了 MC3T3-E1 细胞的黏附、增殖和分化。与原始表面相比，半结晶交联 PCLDA2000/HA 纳米复合材料切割表面上更多暴露的 HA 导致亲水性显著提高，并且显著改善了 MC3T3 细胞的黏附、增殖和分化。这项研究表明，在聚合物/HA 纳米复合材料中，聚合物顶层覆盖了纳米粒子，HA 纳米粒子可能没有得到充分利用。去除该聚合物层可以为骨修复和再生生成更理想的表面和骨诱导性。
