Degradation-Induced Actuation in Oxidation-Responsive Liquid Crystal Elastomers
Degradation-Induced Actuation in Oxidation-Responsive Liquid Crystal Elastomers
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DOI：
10.3390/cryst10050420
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发表时间：
2020-05-01
期刊：
影响因子：
2.7
通讯作者：
Ware, Taylor H.
中科院分区：
文献类型：
--
作者：
Javed, Mahjabeen;Tasmim, Seelay;Ware, Taylor H.
对特定生物条件表现出机械响应的刺激响应材料在响应性、植入性医疗设备方面具有相当大的兴趣。在这里，我们报告了氧化响应型液晶弹性体的合成、加工和表征，这些弹性体表现出可编程的形状变化，以响应活性氧物种。直接墨水写入(DIW)用于制备具有程序分子取向和各向异性力学性能的液晶弹性体(LCEs)。将LCE结构浸泡在不同的介质(氧化、碱性和生理盐水)中，在体温下测量其体外降解情况。氧化敏感的疏水性硫醚键转变为亲水的亚砜和砜基团。这些极性部分的引入导致聚合物网络在水环境中的各向异性膨胀，导致复杂的形状变化。3D打印的单轴带材在氧化介质中沿向列相导向器收缩8%，垂直膨胀16%，而打印的LCE沿方位变形成锥形，其厚度是其原始厚度的19倍。最终，这些LCEs会完全降解。相比之下，在碱性和生理盐水溶液中的LCE没有明显的反应。这些具有可编程形状变化的氧化响应型LCE可以在靶向给药系统和其他诊断和治疗工具中实现广泛的应用。
Stimuli-responsive materials that exhibit a mechanical response to specific biological conditions are of considerable interest for responsive, implantable medical devices. Herein, we report the synthesis, processing and characterization of oxidation-responsive liquid crystal elastomers that demonstrate programmable shape changes in response to reactive oxygen species. Direct ink writing (DIW) is used to fabricate Liquid Crystal Elastomers (LCEs) with programmed molecular orientation and anisotropic mechanical properties. LCE structures were immersed in different media (oxidative, basic and saline) at body temperature to measure in vitro degradation. Oxidation-sensitive hydrophobic thioether linkages transition to hydrophilic sulfoxide and sulfone groups. The introduction of these polar moieties brings about anisotropic swelling of the polymer network in an aqueous environment, inducing complex shape changes. 3D-printed uniaxial strips exhibit 8% contraction along the nematic director and 16% orthogonal expansion in oxidative media, while printed LCEs azimuthally deform into cones 19 times their original thickness. Ultimately, these LCEs degrade completely. In contrast, LCEs subjected to basic and saline solutions showed no apparent response. These oxidation-responsive LCEs with programmable shape changes may enable a wide range of applications in target specific drug delivery systems and other diagnostic and therapeutic tools.