Polycaprolactone (PCL) is a widely used biodegradable polyester for tissue engineering applications when long-term degradation is preferred. In this article, we focused on the analysis of the hydrolytic degradation of virgin and bioactive poly(sodium styrene sulfonate) (pNaSS) functionalized PCL surfaces under simulated physiological conditions (phosphate buffer saline at 25 and 37 °C) for up to 120 weeks with the aim of applying bioactive PCL for ligament tissue engineering. Techniques used to characterize the bulk and surface degradation indicated that PCL was hydrolyzed by a bulk degradation mode with an accelerated degradation—three times increased rate constant—for pNaSS grafted PCL at 37 °C when compared to virgin PCL at 25 °C. The observed degradation mechanism is due to the pNaSS grafting process (oxidation and radical polymerization), which accelerated the degradation until 48 weeks, when a steady state is reached. The PCL surface was altered by pNaSS grafting, introducing hydrophilic sulfonate groups that increase the swelling and smoothing of the surface, which facilitated the degradation. After 48 weeks, pNaSS was largely removed from the surface, and the degradation of virgin and pNaSS grafted surfaces was similar. The cell response of primary fibroblast cells from sheep ligament was consistent with the surface analysis results: a better initial spreading of cells on pNaSS surfaces when compared to virgin surfaces and a tendency to become similar with degradation time. It is worthy to note that during the extended degradation process the surfaces were able to continue inducing better cell spreading and preserve their cell phenotype as shown by collagen gene expressions.

中文翻译：

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聚（苯乙烯磺酸钠）接枝聚己内酯薄膜和纤维的长期水解降解研究：机理研究和细胞反应

聚己内酯 (PCL) 是一种广泛用于组织工程应用的可生物降解聚酯，当需要长期降解时。在本文中，我们重点分析了在模拟生理条件（25 和 37 °C 的磷酸盐缓冲盐水）下长达 120 周的原始和生物活性聚（苯乙烯磺酸钠）（pNaSS）功能化 PCL 表面的水解降解。将生物活性 PCL 应用于韧带组织工程的目的。用于表征本体和表面降解的技术表明，与 25 °C 下的原始 PCL 相比，PCL 通过本体降解模式水解，并且在 37 °C 下 pNaSS 接枝 PCL 的降解速度增加了三倍，速率常数增加了三倍。观察到的降解机制是由于 pNaSS 接枝过程（氧化和自由基聚合），这加速了降解，直到 48 周达到稳定状态。PCL 表面通过 pNaSS 接枝改变，引入亲水性磺酸盐基团，增加表面的溶胀和光滑度，促进降解。48 周后，pNaSS 大部分从表面去除，原始和 pNaSS 接枝表面的降解相似。来自绵羊韧带的原代成纤维细胞的细胞反应与表面分析结果一致：与原始表面相比，细胞在 pNaSS 表面上的初始扩散更好，并且随着降解时间变得相似。值得注意的是，在延长的降解过程中，表面能够继续诱导更好的细胞扩散并保留其细胞表型，如胶原基因表达所示。