Department of Orthopaedic Surgery, University of Connecticut, Farmington, CT 06030-3800, USA.
Biomaterials. 2010 Jun;31(18):4898-908. doi: 10.1016/j.biomaterials.2010.02.058. Epub 2010 Mar 23.
Polyphosphazene-polyester blends are attractive materials for bone tissue engineering applications due to their controllable degradation pattern with non-toxic and neutral pH degradation products. In our ongoing quest for an ideal completely miscible polyphosphazene-polyester blend system, we report synthesis and characterization of a mixed-substituent biodegradable polyphosphazene poly[(glycine ethyl glycinato)(1)(phenyl phenoxy)(1)phosphazene] (PNGEG/PhPh) and its blends with a polyester. Two dipeptide-based blends namely 25:75 (Matrix1) and 50:50 (Matrix2) were produced at two different weight ratios of PNGEG/PhPh to poly(lactic acid-glycolic acid) (PLAGA). Blend miscibility was confirmed by differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Both blends resulted in higher tensile modulus and strength than the polyester. The blends showed a degradation rate in the order of Matrix2<Matrix1<PLAGA in phosphate buffered saline at 37 degrees C over 12 weeks. Significantly higher pH values of degradation media were observed for blends compared to PLAGA confirming the neutralization of PLAGA acidic degradation by polyphosphazene hydrolysis products. The blend components PLAGA and polyphosphazene exhibited a similar degradation pattern as characterized by the molecular weight loss. Furthermore, blends demonstrated significantly higher osteoblast growth rates compared to PLAGA while maintaining osteoblast phenotype over a 21-day culture. Both blends demonstrated improved biocompatibility in a rat subcutaneous implantation model compared to PLAGA over 12 weeks.
聚膦腈-聚酯共混物由于其具有可控制的降解模式，且降解产物具有无毒和中性 pH 值，因此是用于骨组织工程应用的有吸引力的材料。在我们持续追求理想的完全互溶的聚膦腈-聚酯共混体系的过程中，我们报告了一种混合取代的可生物降解的聚膦腈聚(甘氨酸乙酯甘氨酰基)(1)(苯氧基)(1)膦腈及其与聚酯的共混物的合成和表征。两种二肽基共混物，即 25:75(基质 1)和 50:50(基质 2)，以 PNGEG/PhPh 与聚乳酸-羟基乙酸(PLAGA)的两个不同重量比制备。通过差示扫描量热法、傅里叶变换红外光谱和扫描电子显微镜证实了共混物的混溶性。与聚酯相比，两种共混物均表现出更高的拉伸模量和强度。在 37°C 的磷酸盐缓冲盐水中，共混物在 12 周内的降解速率顺序为基质 2<基质 1<PLAGA。与 PLAGA 相比，降解介质的 pH 值明显更高，这证实了聚膦腈水解产物中和了 PLAGA 的酸性降解。共混物成分 PLAGA 和聚膦腈的分子量损失表明它们具有相似的降解模式。此外，与 PLAGA 相比，共混物在 21 天的培养过程中表现出更高的成骨细胞生长率，同时保持成骨细胞表型。与 PLAGA 相比，两种共混物在大鼠皮下植入模型中均表现出改善的生物相容性，持续 12 周。
