Goonasekera Chandhi S, Jack Kevin S, Cooper-White Justin J, Grøndahl Lisbeth
School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia.
J Mater Chem B. 2016 Jan 21;4(3):409-421. doi: 10.1039/c5tb02255j. Epub 2015 Dec 15.
The dispersion behaviour of hydroxyapatite nanoparticles (HAP) and surface-modified HAP was studied in 1,4-dioxane (DO), water and poly(ε-caprolactone) (PCL) solutions and the relationship between these and the dispersion in composite PCL scaffolds prepared by thermally induced phase separation (TIPS) was examined. Investigation of the change in particle sizes by dynamic light scattering, showed that the modification of HAP by adsorption or covalent attachment of heparin via a 3-aminopropyltriethoxysilane (APTES) layer improved the dispersion stability of the particles in water/DO mixtures, while no improvement was observed in DO. The distribution of the particles within the composite scaffolds was determined using a combination of transmission electron microscopy and a calcium quantification method which was used to determine distribution of the particles in the vertical direction. While the scaffolds fabricated in DO had particles embedded within the walls of the scaffold, the scaffolds fabricated in a DO/water mixed solvent showed the particles partitioned to the surface of the scaffold walls, which is likely because the particles acted as interface stabilisers and were not miscible with the PCL rich phase. Therefore, it can be concluded that the polymer-solvent system used, as well as the phase separation mechanism that occurs, significantly influences the distribution of the particles in the scaffolds and thus the particle behaviour in solution is not necessarily a good predictor for the ability to fabricate scaffolds with a high degree of particle dispersion and hence for overall materials performance. Bulk crystallinity and compressive modulus were examined and it was determined that no significant changes occurred compared with the pristine PCL, while the surface bioactivity of the scaffolds had improved significantly, indicating that the particles were present at the polymer-solution interface.
研究了羟基磷灰石纳米颗粒（HAP）和表面改性HAP在1,4-二氧六环（DO）、水和聚（ε-己内酯）（PCL）溶液中的分散行为，并考察了它们与通过热诱导相分离（TIPS）制备的复合PCL支架中分散情况的关系。通过动态光散射研究粒径变化，结果表明，通过3-氨丙基三乙氧基硅烷（APTES）层吸附或共价连接肝素对HAP进行改性，可提高颗粒在水/DO混合物中的分散稳定性，而在DO中未观察到改善。使用透射电子显微镜和钙定量方法相结合来确定复合支架内颗粒的分布，钙定量方法用于确定颗粒在垂直方向上的分布。在DO中制备的支架，颗粒嵌入支架壁内；而在DO/水混合溶剂中制备的支架，颗粒分布在支架壁表面，这可能是因为颗粒起到了界面稳定剂的作用，且与富含PCL的相不相容。因此，可以得出结论，所使用的聚合物-溶剂体系以及发生的相分离机制，会显著影响颗粒在支架中的分布，因此溶液中的颗粒行为不一定能很好地预测制备具有高度颗粒分散性的支架的能力，进而也不能很好地预测整体材料性能。研究了本体结晶度和压缩模量，结果表明与原始PCL相比没有显著变化，而支架表面生物活性显著提高，这表明颗粒存在于聚合物-溶液界面处。
