Poly(l-lactide) (PLLA) as one of the most well-known biodegradable polyesters has been studied extensively for bone tissue engineering. If being properly programmed, scaffolds from PLLA can also be endowed with the capability of shape memory. However, several noted issues, for example, mechanical brittleness, high glass transition temperature T_g, and relatively poor shape retention and recovery properties, necessitate modification of the PLLA to improve its application efficacy in physiological conditions. This study is proposed to modify PLLA by having the biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) incorporated to form ultrafine composite fibers (i.e., PLLA-PHBV) through electrospinning. Different pairs of PLLA-PHBV at the varying mass ratios of 10:0, 9:1, 8:2, 7:3, 6:4, and 0:10 can be successfully electrospun into fibrous form with the fineness of 2–3 μm. Incorporation of PHBV enables to give rise to desired T_g decreases and also, interestingly, increases in the Young's modulus of the PLLA-PHBV blends, while gradually increasing the PHBV mass ratios up to 30%. The PLLA-PHBV (7:3) formulation is identified to present excellent shape memory properties with high shape fixing ratio (>98%) and shape recovery ratio (>96%) compared to the unmodified PLLA fiber counterpart. Moreover, the PLLA-PHBV (7:3) fibers also show enhanced osteogenesis-inducing ability in the mouse bone mesenchymal stem cells, even under nonosteoinductive conditions. Collectively, for the first time this study demonstrates the enhanced shape memory and osteogenesis capabilities of the electrospun PLLA-PHBV composite fibers, and the researched PLLA-PHBV (7:3) fiber system could be potentially applied as a multifunctional scaffolding material for applications in bone tissue repair and regeneration.

中文翻译：

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电纺聚（3-羟基丁酸酯-co-3-羟基戊酸酯）改性聚（l-丙交酯）纤维垫的形状记忆和成骨能力。

聚（l-丙交酯）（PLLA）作为最著名的可生物降解聚酯之一，已被广泛研究用于骨组织工程。如果正确编程，来自 PLLA 的支架也可以被赋予形状记忆能力。然而，一些值得注意的问题，例如机械脆性、高玻璃化转变温度T _g以及相对较差的形状保持和恢复性能，需要对 PLLA 进行修改以提高其在生理条件下的应用效果。这项研究中，提出了由具有可生物降解的聚（3-羟基丁酸酯修改PLLA共-3-羟基戊酸）（PHBV）通过静电纺丝形成超细复合纤维（即PLLA-PHBV）。不同质量比为 10:0、9:1、8:2、7:3、6:4 和 0:10 的不同对 PLLA-PHBV 可以成功电纺成细度为 2-3 的纤维形式微米。PHBV的掺入使得能够产生所需的Ť_克此外，有趣的是，PLLA-PHBV 混合物的杨氏模量增加，同时 PHBV 质量比逐渐增加至 30%。与未改性的 PLLA 纤维对应物相比，PLLA-PHBV (7:3) 配方被确定具有优异的形状记忆特性，具有高形状固定率 (>98%) 和形状恢复率 (>96%)。此外，即使在非骨诱导条件下，PLLA-PHBV (7:3) 纤维也显示出增强的小鼠骨间充质干细胞的成骨诱导能力。总的来说，这项研究首次证明了电纺 PLLA-PHBV 复合纤维和研究的 PLLA-PHBV (7: