PDF(Pubmed)
Abstract：
Thermoresponsive shape memory polymers (SMPs) prepared from UV-curable poly(ε-caprolactone) (PCL) macromers have the potential to create self-fitting bone scaffolds, self-expanding vaginal stents, and other shape-shifting devices. To ensure tissue safety during deployment, the shape actuation temperature (i.e., the melt transition temperature or Tm of PCL) must be reduced from ∼55 °C that is observed for scaffolds prepared from linear-PCL-DA (Mn ∼ 10 kg mol-1). Moreover, increasing the rate of biodegradation would be advantageous, facilitating bone tissue healing and potentially eliminating the need for stent retrieval. Herein, a series of six UV-curable PCL macromers were prepared with linear or 4-arm star architectures and with Mns of 10, 7.5, and 5 kg mol-1, and subsequently fabricated into six porous scaffold compositions (10k, 7.5k, 5k, 10k★, 7.5k★, and 5k★) via solvent casting particulate leaching (SCPL). Scaffolds produced from star-PCL-tetraacrylate (star-PCL-TA) macromers produced pronounced reductions in Tm with decreased Mnversus those formed with the corresponding linear-PCL-diacrylate (linear-PCL-DA) macromers. Scaffolds were produced with the desired reduced Tm profiles: 37 °C < Tm < 55 °C (self-fitting bone scaffold), and Tm ≤ 37 °C (self-expanding stent). As macromer Mn decreased, crosslink density increased while % crystallinity decreased, particularly for scaffolds prepared from star-PCL-TA macromers. While shape memory behavior was retained and radial expansion pressure increased, this imparted a reduction in modulus but with an increase in the rate of degradation.
摘要：
由UV可固化的聚（ε-己内酯）（PCL）大分子单体制备的热响应形状记忆聚合物（SMPs）具有创建自适应骨支架的潜力，自膨式阴道支架,和其他变形装置。为确保展开期间的组织安全,形状致动温度(即，对于由线性PCL-DA（Mn〜10kgmol-1）制备的支架，PCL）的熔融转变温度或Tm必须从〜55°C降低。此外，提高生物降解速率将是有利的，促进骨组织愈合，并可能消除支架取出的需要。在这里，制备了一系列六种可UV固化的PCL大分子单体，它们具有线性或4臂星形结构，Mns分别为10、7.5和5kgmol-1，随后制成六种多孔支架组合物（10k，7.5k，5k，10k★,7.5k★,和5k★)通过溶剂浇铸颗粒浸出(SCPL)。与相应的线性-PCL-二丙烯酸酯（线性-PCL-DA）大分子单体形成的支架相比，由星形-PCL-四丙烯酸酯（星形-PCL-TA）大分子单体产生的支架的Tm显着降低，Mn降低。制备具有所需降低的Tm曲线的支架:37°C
