这项工作是由美国国家职业基金会（CBET-1336073至RV），ACS的石油研究基金（52345-DN17至RV），美国心脏协会（BGIA到JGJ），美国国家科学基金会（CAREER支持CBET-1055942至JGJ），健康/美国国家心脏，肺和血液研究所（1R21HL110330到JGJ），路易斯和桃子欧文和得克萨斯儿童医院的国家机构。

1.不结盟聚硅氧烷LCES的合成<ol><li>结合166.23毫克反应性液晶元（4-甲氧基苯基4-（3-丁烯氧基）苯甲酸酯），40毫克聚（hydromethylsiloxane），以及12.8毫克交联剂（1,4-二（10- undecenyloxybenzene）30 0.6无水毫升甲苯在一个小管形瓶（约13毫米直径和长度100毫米）装入带有搅拌棒，搅拌在35℃下该溶液25分钟使其溶解。 </li><li>在一个单独的小瓶中，制备1重量％二氯（1,5-环辛二烯）的二氯甲烷 - 铂（Ⅱ）催化剂的溶液。通过吸管从步骤1.1加入30微升的催化剂溶液试剂，搅拌均匀，并且将溶液倒入一个特制的3厘米（×2cm的×1厘米）矩形聚四氟乙烯（PTFE）的模具。覆盖在60℃下的在加热炉载玻片和地点松散模具30分钟，同时振摇周期性的前15分钟内，以除去气泡。 </li><li>从加热炉兼首席运营官删除模具l当通过浇注液态氮成一个小容器和2秒接触与液体氮的聚四氟乙烯模具底部液氮中。 <ol><li>一旦混合物冷却，小心地从模具使用金属铲去除弹性体和放置在PTFE板的顶部。修剪使用刀片的LCE的边缘和切割沿其长度LCE分成三个相等大小的块（约2.7厘米长和0.5厘米宽）。 </li></ol></li><li>由一端挂每一块到水平杆和附加10纸夹4.4克至LCE的另一端。使用磁带举行的地方LCE，并增加在10分钟为增量时间纸夹之一。挂LCE在室温下7天，并指出在长度和均匀性的变化。丢弃撕裂或断裂的样品。除去样品并在室温储存。 </li></ol> 2.电响应聚硅氧烷LCE纳米复合材料的制备<ol><li>为了通过分散的炭黑制备纳米复合材料LCE散装样品，首先重复步骤1.1 - 1.4以上。添加4.38毫克炭黑纳米粒子含有反应性液晶元，交联剂和硅氧烷反应溶液中。总共使用5回形针，而不是10装载的。 </li><li>为了增加额外的碳黑粒子的LCE表面，制备1％重量/在甲苯炭黑纳米粒子v溶液。超声处理20分钟以分散纳米颗粒，然后倒入分散到皮氏培养皿。从步骤2.1 6小时的纳米颗粒分散体的沉浸LCES。 </li><li> 6小时后，用移液管撤回从培养皿的溶液，并允许弹性体在空气中干燥。使用磁带或棉签轻轻擦拭表面超额碳粒子。 </li></ol> 3.环氧基可逆LCES的制备<ol><li>混合246.15毫克4,4&#39;-二缩水甘油基31，101毫克癸二酸，71.6毫克十六烷二酸，以及76毫克羧癸基封端的聚二的甲基硅氧烷在一个特制的3厘米（×2cm的×1厘米）的矩形模具PTFE。通过放置在180℃的加热板上加热样品。 <ol><li>添加11.48毫克（1,5,7-三氮杂二环[4.4.0]癸-5-烯）催化剂，并使用金属镊子预先被加热到180℃搅拌。继续反应，直到混合物形成凝胶，在大约20分钟，并定期搅拌以除去由反应产生的气泡。 </li></ol></li><li>从加热板取下PTFE舟，并允许冷却到室温。用剃刀刀片的弹性体从聚四氟乙烯模具分离。 </li><li>放置两种PTFE片材在180℃的聚合物按。从步骤3.2的PTFE片材之间放置弹性体和样品压缩至厚度为0.3 - 0.5毫米。继续在180℃加热4小时。 </li><li>取出样品，并冷却至室温。切取试样成矩形件（大约2.5厘米长0.5厘米宽）。用加热烘箱内聚酰亚胺胶带一端悬挂样品。附加12 PAperclips（8.88克）到样品的自由端。加热炉的温度设定为165℃CO / N或12 - 16小时。 </li><li>除去从加热炉中的高弹体，并注意在长度变化。热在电炉上的样品至80℃，以除去残余应力，然后冷却回室温。 </li></ol> 4.测试与表征LCES的<ol><li>通过在电炉上于120℃，摄像用照相机加热样品测量可逆菌株。注意冷却回到室温后在RT初始样品长度，加热至120℃后的样品长度，且长度。 LCES应约30％收缩并返回到它们的初始长度上冷却。 参见图1A和1B所示的例子的图像。 </li><li>通过在加热/共切削从各LCE和扫描一小块0℃至150℃分析用差示扫描量热（DSC）相变温度和玻璃化转变奥林·10℃/ min的速度32,33。 </li><li>量化液晶取向的通过X射线衍射测定的程度。将样品与2D成像能力的X射线衍射装置33参见图 2中所示示例的衍射图像。 注意:衍射图像应当是各向异性的，这反映了LCE 33的对准。聚硅氧烷LCES是向列型和环氧基LCES表现出近晶相。 </li><li>测量LCE和长度变化的刚度，并使用动态力学分析（DMA）的宽度。记录长度和刚度的变化与温度的LCES和作为电势为LCE纳米复合材料的功能的功能。 <ol><li>对于热机械测量，用剃刀刀片手动剪切样品为2厘米×0.3厘米尺寸和张力夹具之间小心紧固英寸应用的1万力，以消除任何松弛。 <ol><li>热平衡，在30℃弗洛样品通过加热和冷却循环以5℃/分钟结婚。从30℃热样品到120℃。温度的变化产生在样品，其中在DMA测量期间被记录的长度和宽度的变化。见一个LCE样品的热测量图3A。 </li></ol></li><li>机电测量，手动剪切LCE纳米复合材料样品以2厘米×0.3厘米的尺寸，并在使用银环氧树脂的LCE纳米复合材料的相对端粘上的铜线。使用固定张力LCE纳米复合材料与锰1夹紧张。 <ol><li>通过铜线在一个电压范围内施加的电势从0 - 60伏，60赫兹的频率，和一个开/关的脉冲持续时间从0.1秒 - 30秒。 </li><li>记录形状的变化响应于的电势。应用的1万固定力去除松弛。在夹具的位置变化对应于塑造样品中的变化。见Figu重新3B为LCE纳米复合材料样品的机电测量。 </li></ol></li></ol></li></ol>通过LCE纳米复合材料的电刺激5.激活细胞培养<ol><li>治疗LCE纳米复合材料的一个表面之下的氧气等离子体30秒。自旋的甲苯浇铸聚苯乙烯的溶液300微升（1％重量/体积）3300的转速在等离子体清洁的表面的顶部1分钟。干燥在真空下，弹性体12小时，以除去甲苯，和治疗使用氧等离子体进行30秒的LCE纳米复合材料的聚苯乙烯包覆的表面。 </li><li>放置在70％的乙醇溶液LCE纳米复合材料30分钟以消毒的表面上。 <ol><li>洗用磷酸盐缓冲盐水的LCE纳米复合材料和LCE转移到干燥的培养皿与聚苯乙烯包覆侧朝上。通过在5毫升​​大鼠尾I型胶原溶液（50μg/ ml的在0.02N的乙酸）的浸渍涂层的LCE的整个表面。孵育LCEñanocomposite在37℃和5％CO 2的至少30分钟。 </li></ol></li><li>隔离乳鼠心肌细胞，并在高血清电镀媒体暂停如先前报道11。 <ol><li> 600000细胞/ cm 2 - 100,000的密度描述如上关于LCE基板的顶板细胞。约24小时后，将细胞转移到低血清维持培养基（DMEM，18.5％的M199，5％HS，1％FBS和抗生素）。允许心肌附加和增殖的LCE的表面上4天。 </li></ol></li><li>使用的3-D打印机和使用使用制造商的方案在图4所示的容器的概略制造定制容器设计。 注意:3D印刷容器是具有为60毫米×40mm的×20毫米和50毫米×30毫米×15 mm内尺寸的外尺寸的矩形容器。在两个侧面，有用于插入导电性碳棒两组为5毫米的孔。缺口周围的孔和到容器的顶部边缘ES允许用于放置一矩形塑料片横跨容器（52.5毫米×12毫米×4mm的尺寸）在两端保持在适当位置的LCE。孔之间的距离是在容器的一侧3毫米，和凹口位于孔的周围，如图4，这被设计成与上述的LCE衬底的尺寸相兼容。如图中材料补充导电性碳杆通过商业供应商获得。 <ol><li>通过跨血管插入孔炭棒和使用医用有机硅胶粘剂的地方举行。固化粘合剂O / N。 </li></ol></li><li>转印LCE纳米复合材料与心​​肌填充有细胞培养维持培养基并用连接到电​​源并联导电性碳棒定制3D印刷容器中。放置LCE整个炭棒和固定在一端，以确保电接触。 <ol><li>插入通过在三维容器中的凹口的​​矩形塑料片的一个或两个端部保持在适当位置的LCE，但松散放置此在LCE样品。通过40伏交流电的电势的一个5秒的应用开/关时间电刺激LCE为总共24小时。 </li></ol></li><li>染色使用钙黄绿素AM如先前11描述的活细胞膜。 </li><li>对于细胞核染色，覆盖含DAPI成像之前安装介质中的倒置荧光显微镜下的细胞。使用ImageJ的计数活细胞的数量和使用最佳拟合函数确定细胞对准的角度。 </li></ol> 6.主动细胞培养与使用LCES直接加热<ol><li>重复步骤5.1 - 5.3以上使用纯LCE没有炭黑粒子添加。这个过程也详细在现有出版物11中所述 。 </li><li>转移与心肌细胞LCE到Petri网ð细胞培养维持培养基和0.5"×2"卡普顿电阻加热器杂交。供应热量以通过接通电阻加热器12 W.循环加热和关闭电源以5秒的间隔的热量的至少24小时的LCE。 </li></ol>

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T., Wang, X., Liu, T., Keller, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible+and+Rapid+Laser+Actuation+of+Liquid+Crystalline+Elastomer+Micropillars+with+Inclusion+of+Gold+Nanoparticles.">Reversible and Rapid Laser Actuation of Liquid Crystalline Elastomer Micropillars with Inclusion of Gold Nanoparticles.</a> Adv. Funct. Mater. 25 (20), 3022-3032 (2015).</li><li>Marshall, J. E., Terentjev, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photo-sensitivity+of+dye-doped+liquid+crystal+elastomers.">Photo-sensitivity of dye-doped liquid crystal elastomers.</a> Soft Matter. 9 (35), 8547-8551 (2013).</li><li>Marshall, J. E., Ji, Y., Torras, N., Zinoviev, K., Terentjev, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon-nanotube+sensitized+nematic+elastomer+composites+for+IR-visible+photo-actuation.">Carbon-nanotube sensitized nematic elastomer composites for IR-visible photo-actuation.</a> Soft Matter. 8 (5), 1570-1574 (2012).</li><li>Camargo, C. J., Campanella, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localised+Actuation+in+Composites+Containing+Carbon+Nanotubes+and+Liquid+Crystalline+Elastomers.">Localised Actuation in Composites Containing Carbon Nanotubes and Liquid Crystalline Elastomers.</a> Macromol. Rapid Commun. 32, 1953-1959 (2011).</li><li>Ahir, S. V., Squires, A. M., Tajbakhsh, A. R., Terentjev, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared+actuation+in+aligned+polymer-nanotube+composites.">Infrared actuation in aligned polymer-nanotube composites.</a> Phys Rev B. 73 (8), 085420 (2006).</li><li>K&#252;pfer, J., Finkelmann, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nematic+liquid+single+crystal+elastomers.">Nematic liquid single crystal elastomers.</a> Macromol Chem Rapid Commun. 12 (12), 717-726 (1991).</li><li>Ali, S. A., Al-Muallem, H. A., Rahman, S. U., Saeed, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bis-isoxazolidines:+A+new+class+of+corrosion+inhibitors+of+mild+steel+in+acidic+media.">Bis-isoxazolidines: A new class of corrosion inhibitors of mild steel in acidic media.</a> Corros. Sci. 50 (11), 3070-3077 (2008).</li><li>Giamberjni, M., Amendola, E., Carfagna, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+Crystalline+Epoxy+Thermosets.">Liquid Crystalline Epoxy Thermosets.</a> Mol. Cryst. Liq. Cryst. Sci. Technol. Sect. Mol. Cryst. Liq. Cryst. 266 (1), 9-22 (1995).</li><li>Agrawal, A., Luchette, P., Palffy-Muhoray, P., Biswal, S. L., Chapman, W. G., Verduzco, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+wrinkling+in+liquid+crystal+elastomers.">Surface wrinkling in liquid crystal elastomers.</a> Soft Matter. 8 (27), 7138-7142 (2012).</li><li>Agrawal, A., Chipara, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+self-stiffening+in+liquid+crystal+elastomers.">Dynamic self-stiffening in liquid crystal elastomers.</a> Nat Commun. 4, 1739 (2013).</li><li>Sharma, A., Neshat, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodegradable+and+Porous+Liquid+Crystal+Elastomer+Scaffolds+for+Spatial+Cell+Cultures.">Biodegradable and Porous Liquid Crystal Elastomer Scaffolds for Spatial Cell Cultures.</a> Macromol. Biosci. 15 (2), 200-214 (2015).</li><li>Yeh, L. C., Dai, C. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neat+poly(ortho-methoxyaniline)+electrospun+nanofibers+for+neural+stem+cell+differentiation.">Neat poly(ortho-methoxyaniline) electrospun nanofibers for neural stem cell differentiation.</a> J. Mater. Chem. B. 1, 5469-5477 (2013).</li><li>Krause, S., Dersch, R., Wendorff, J. H., Finkelmann, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photocrosslinkable+Liquid+Crystal+Main-Chain+Polymers:+Thin+Films+and+Electrospinning.">Photocrosslinkable Liquid Crystal Main-Chain Polymers: Thin Films and Electrospinning.</a> Macromol. Rapid Commun. 28 (21), 2062-2068 (2007).</li><li>Liu, D., Broer, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light+controlled+friction+at+a+liquid+crystal+polymer+coating+with+switchable+patterning.">Light controlled friction at a liquid crystal polymer coating with switchable patterning.</a> Soft Matter. 10 (40), 7952-7958 (2014).</li></ol>

The authors have nothing to disclose.

In order to produce monodomain LCEs, the LCEs need to be uniaxially loaded during crosslinking. This is challenging in practice because the LCE is loaded when it is only partially crosslinked, and therefore is not mechanically robust and can easily break or tear. The procedure described above (steps 1.1 - 1.4) can produce monodomain LCEs consistently. One critical step is the removal of the LCE from the PTFE mold for loading at the appropriate time. If the LCE is removed too quickly, it will easily break or tear. On the...

可以表现出快速的，可逆的，可编程的形状改变的材料是可取的一些新兴的应用1-9。形状响应支架可以帮助伤口愈合，治疗7。人工机器人可以在勘探或在有害或不安全的人类10环境中执行任务的帮助。形状响应弹性体是所希望的用于在活性细胞培养物，其中细胞在活性环境中培养的用11-14其它应用包括包装，传感，和药物递送。 液晶弹性体（LCE）与液晶订货15-20的聚合物网络。 LCES通过柔性聚合物网络与被称为介晶液晶分子相结合进行。 LCES的响应是从液晶秩序的偶合而得到影响介晶的排序的聚合物网络中的菌株，并刺激将基因率网的菌株，反之亦然。为了实现在没有外部负载的大的和可逆的形状变化，介晶必须在LCE单个方向对准。在LCES工作的一个常见实用的挑战是产生单畴LCES。另一个挑战是产生形状的变化响应于刺激其他比直接加热。这可以通过增加纳米颗粒或染料来LCE网络21-28来完成。 这里，我们证明单畴LCES和LCE纳米复合材料的制备。首先，我们证明了使用两步法首先由枯否等报道单畴LCES 的制备。29，这仍然是一种制备单畴LCES，但实现取向均匀性和一致性的样品之间是具有挑战性的最流行 ​​的和公知的方法。我们证明可以使用标准的实验室设备很容易实现的方法，包括抽样的全部细节处理和准备。下一步，我们表明导电炭黑纳米颗粒如何可以被添加到LCES以产生导电性，电响应LCES。然后我们证明环氧基LCES的合成和对准。这些材料表现出可交换网络键，并且可以通过加热到高温，并施加均匀的载荷对齐。所有LCES通过宏观样品成像，X射线衍射测量和动态力学分析表征。最后，我们证明LCES为活跃细胞培养形状响应衬底中的一个潜在的应用。

<table><tbody><tr><td>4-methoxyphenyl 4-(3-butenyloxy)benzoate</td><td>TCI America</td><td>M2106</td><td>Reactive mesogen</td></tr><tr><td>poly(methylhydrosiloxane)</td><td>Gelest</td><td>HMS-993</td><td>Reactive polysiloxane</td></tr><tr><td>1,4-di(10-undecenyloxybenzene)</td><td>N/A</td><td>N/A</td><td>see: Ali, S. A., Al-Muallem, H. A., Rahman, S. U. &amp;amp; Saeed, M. T. Bis-isoxazolidines: A new class of corrosion inhibitors of mild steel in acidic media. Corrosion Science. 50 (11), 3070&amp;ndash;3077, doi:10.1016/j.corsci.2008.08.011 (2008)</td></tr><tr><td>(dichloro(1,5-cyclooctadiene)-platinum(II)&amp;nbsp;</td><td>Sigma Aldrich</td><td>244937</td><td>Pt catalyst</td></tr><tr><td>PTFE mold</td><td>N/A</td><td>N/A</td><td>fabricated at Rice machine shop</td></tr><tr><td>carbon black nanoparticles</td><td>Cabot</td><td>VULCAN&amp;reg;&amp;nbsp;XC72R</td><td>used in the synthesis of LCE nanocomposites</td></tr><tr><td>polystyrene</td><td>Sigma Aldrich</td><td>331651</td><td>linear polystyrene&amp;nbsp;</td></tr><tr><td>4,4&#039;-diglycidyloxybiphenyl</td><td>N/A</td><td>N/A</td><td>see:&amp;nbsp; Giamberjni, M., Amendola, E. &amp;amp; Carfagna, C. Liquid Crystalline Epoxy Thermosets. Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals. 266 (1), 9&amp;ndash;22, doi:10.1080/10587259508033628 (1995).</td></tr><tr><td>sebacic acid</td><td>Sigma Aldrich</td><td>283258</td><td>C8 linking group for epoxy-LCE synthesis</td></tr><tr><td>hexadecanedioic acid</td><td>Sigma Aldrich</td><td>177504</td><td>C16 linking group for epoxy-LCE synthesis</td></tr><tr><td>carboxydecyl-terminated polydimethylsiloxane</td><td>Gelest</td><td>DMS-B12</td><td>Siloxane linking group for epoxy-LCE synthesis</td></tr><tr><td>1,5,7-triazabicyclo[4.4.0] dec-5-ene</td><td>Sigma Aldrich</td><td>345571</td><td>catalyst for reversible LCEs</td></tr><tr><td>carbon rods</td><td>Ladd Research&amp;nbsp;</td><td>30250</td><td>used in cell culture experiments</td></tr><tr><td>medical grade silicone adhesive</td><td>Silbione</td><td>MED ADH 4100 RTV</td><td>used to adhere carbon rods to vessel</td></tr></tbody></table>

preparation of monodomain liquid crystal elastomers and liquid crystal elastomer nanocomposites

LCES是形状响应材料具有完全可逆的形状变化和在医学应用潜力，组织工程，人工肌肉，并作为软机器人。这里，我们证明形状响应液晶弹性体（LCES）和LCE纳米复合材料的制备其形状的响应的表征，机械性能，和显微组织沿。两种类型LCES的 - 聚硅氧烷 - 基和环氧基 - 合成，对齐，和特征。基于聚硅氧烷的LCES通过两个交联步骤中，所施加的负载下的第二次制备，产生单畴LCES。聚硅氧烷LCE纳米复合材料是通过加入导电性炭黑纳米粒子的制备，无论是在整个批量的LCE的并向LCE表面。基于环氧LCES通过可逆酯化反应制备。基于环氧LCES通过一个单轴负载在升高（160℃）t时应用对准emperatures。对准LCES和LCE纳米复合材料使用的成像，二维X射线衍射测量，差示扫描量热法，和动态力学分析的组合，其特征相对于可逆应变，机械刚度，以及液晶排序。 LCES和LCE纳米复合材料可以用热和/或电势被刺激可控产生在细胞培养基的菌株，我们证明LCES的应用作为使用定做装置用于细胞培养的形状响应衬底。

单畴LCES的形状响应由于与液晶有序网络结构的耦合。加热LCES导致在液晶有序参数的降低，产生沿主取向方向上的聚合物网络的缩写。这很容易通过放置一个LCE在电炉上可视化， 如图1A和1B。在从室温，沿着样品的长度LCE合同，上述各向同性转变温度收缩加热是一个最大值。样本也将成为上述各向同性转变温度光学透明的，而有些朦胧为低于各向?...

Watch this Scientific Journal Video about Preparation of Monodomain Liquid Crystal Elastomers and Liquid Crystal Elastomer Nanocomposites at JoVE.com

Preparation of Monodomain Liquid Crystal Elastomers and Liquid Crystal Elastomer Nanocomposites

单域液晶的弹性体和液晶橡胶纳米复合材料的制备

We demonstrate the preparation of siloxane-based and epoxy-based liquid crystal elastomers (LCEs) and LCE nanocomposites. The LCEs are characterized with respect to reversible strain, liquid crystal ordering, and stiffness. As a potential application, we demonstrate their use as shape-responsive substrates in a custom device for active cell culture.

LCEs are shape-responsive materials with fully reversible shape change and potential applications in medicine, tissue engineering, artificial muscles, and ...

preparation-monodomain-liquid-crystal-elastomers-liquid-crystal

Research

JoVE Journal

Bioengineering

12.5K 次观看.  Rice University. We demonstrate the preparation of siloxane-based and epoxy-based liquid crystal elastomers (LCEs) and LCE nanocomposites. The LCEs are characterized with respect to reversible strain, liquid crystal ordering, and stiffness. As a potential application, we demonstrate their use as shape-responsive substrates in a custom device for active cell culture.

视频: Preparation of Monodomain Liquid Crystal Elastomers and Liquid Crystal Elastomer Nanocomposites

Utilization of Plasmonic and Photonic Crystal Nanostructures for Enhanced Micro- and Nanoparticle Manipulation

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological research. Perhaps the most widely used physical force to achieve noninvasive manipulation of small particles has been dielectrophoresis(DEP).1 However, DEP on its own lacks the versatility and precision that are desired when manipulating cells since it is traditionally done with stationary electrodes. Optical tweezers, which utilize a three dimensional electromagnetic field gradient to exert forces on small particles, achieve this desired versatility and precision.2 However, a major drawback of this approach is the high radiation intensity required to achieve the necessary force to trap a particle which can damage biological samples.3 A solution that allows trapping and sorting with lower optical intensities are optoelectronic tweezers (OET) but OET's have limitations with fine manipulation of small particles; being DEP-based technology also puts constraint on the property of the solution.4,5
This video article will describe two methods that decrease the intensity of the radiation needed for optical manipulation of living cells and also describe a method for orientation control. The first method is plasmonic tweezers which use a random gold nanoparticle (AuNP) array as a substrate for the sample as shown in Figure 1. The AuNP array converts the incident photons into localized surface plasmons (LSP) which consist of resonant dipole moments that radiate and generate a patterned radiation field with a large gradient in the cell solution. Initial work on surface plasmon enhanced trapping by Righini et al and our own modeling have shown the fields generated by the plasmonic substrate reduce the initial intensity required by enhancing the gradient field that traps the particle.6,7,8 The plasmonic approach allows for fine orientation control of ellipsoidal particles and cells with low optical intensities because of more efficient optical energy conversion into mechanical energy and a dipole-dependent radiation field. These fields are shown in figure 2 and the low trapping intensities are detailed in figures 4 and 5. The main problems with plasmonic tweezers are that the LSP's generate a considerable amount of heat and the trapping is only two dimensional. This heat generates convective flows and thermophoresis which can be powerful enough to expel submicron particles from the trap.9,10 The second approach that we will describe is utilizing periodic dielectric nanostructures to scatter incident light very efficiently into diffraction modes, as shown in figure 6.11 Ideally, one would make this structure out of a dielectric material to avoid the same heating problems experienced with the plasmonic tweezers but in our approach an aluminum-coated diffraction grating is used as a one-dimensional periodic dielectric nanostructure. Although it is not a semiconductor, it did not experience significant heating and effectively trapped small particles with low trapping intensities, as shown in figure 7. Alignment of particles with the grating substrate conceptually validates the proposition that a 2-D photonic crystal could allow precise rotation of non-spherical micron sized particles.10 The efficiencies of these optical traps are increased due to the enhanced fields produced by the nanostructures described in this paper.

Plasmonic tweezers and photonic crystal nanostructures are shown to produce useful enhancements in the efficiency and orientation control of optically trapping micro- and nano-particles.

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological ...

科研

生物工程

Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including numerous stereoisomers1,2. These metabolites can be formed from free or esterified fatty acids. Many of these oxidized metabolites have biological activity and have been implicated in various diseases including cardiovascular and neurodegenerative diseases, asthma, and cancer3-7. Oxidized bioactive lipids can be formed enzymatically or by reactive oxygen species (ROS). Enzymes that metabolize fatty acids include cyclooxygenase (COX), lipoxygenase (LO), and cytochromes P450 (CYPs)1,8. Enzymatic metabolism results in enantioselective formation whereas ROS oxidation results in the racemic formation of products.
While this protocol focuses primarily on the analysis of AA- and some LA-derived bioactive metabolites; it could be easily applied to metabolites of other fatty acids. Bioactive lipids are extracted from cell lysate or media using liquid-liquid (l-l) extraction. At the beginning of the l-l extraction process, stable isotope internal standards are added to account for errors during sample preparation. Stable isotope dilution (SID) also accounts for any differences, such as ion suppression, that metabolites may experience during the mass spectrometry (MS) analysis9. After the extraction, derivatization with an electron capture (EC) reagent, pentafluorylbenzyl bromide (PFB) is employed to increase detection sensitivity10,11. Multiple reaction monitoring (MRM) is used to increase the selectivity of the MS analysis. Before MS analysis, lipids are separated using chiral normal phase high performance liquid chromatography (HPLC). The HPLC conditions are optimized to separate the enantiomers and various stereoisomers of the monitored lipids12. This specific LC-MS method monitors prostaglandins (PGs), isoprostanes (isoPs), hydroxyeicosatetraenoic acids (HETEs), hydroxyoctadecadienoic acids (HODEs), oxoeicosatetraenoic acids (oxoETEs) and oxooctadecadienoic acids (oxoODEs); however, the HPLC and MS parameters can be optimized to include any fatty acid metabolites13.
Most of the currently available bioanalytical methods do not take into account the separate quantification of enantiomers. This is extremely important when trying to deduce whether or not the metabolites were formed enzymatically or by ROS. Additionally, the ratios of the enantiomers may provide evidence for a specific enzymatic pathway of formation. The use of SID allows for accurate quantification of metabolites and accounts for any sample loss during preparation as well as the differences experienced during ionization. Using the PFB electron capture reagent increases the sensitivity of detection by two orders of magnitude over conventional APCI methods. Overall, this method, SID-LC-EC-atmospheric pressure chemical ionization APCI-MRM/MS, is one of the most sensitive, selective, and accurate methods of quantification for bioactive lipids.

This protocol will demonstrate the extraction and analysis of free and esterified bioactive fatty acids from cells. Fatty acids are accurately quantified using stable isotope dilution, chiral liquid chromatography, electron capture atmospheric chemical ionization multiple reaction monitoring mass spectrometry (SID-LC-ECAPCI-MRM/MS).

有针对性的稳定同位素稀释液相色谱 - 质谱法分析细胞脂质提取

The metabolism of fatty acids, such as arachidonic acid (AA) and linoleic acid (LA), results in the formation of oxidized bioactive lipids, including ...

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials.

A novel methodology is presented to synthesize and program main-chain liquid-crystalline elastomers using commercially available starting monomers. A wide range of thermomechanical properties was tailored by adjusting the amount of crosslinker, while the actuation performance was dependent on the amount of applied strain during programming.

的可编程主链液晶性弹性体用双级硫醇丙烯酸酯反应合成

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline ...

化学

In situ TEM of Biological Assemblies in Liquid

Researchers regularly use Transmission Electron Microscopes (TEMs) to examine biological entities and to assess new materials. Here, we describe an additional application for these instruments- viewing viral assemblies in a liquid environment. This exciting and novel method of visualizing biological structures utilizes a recently developed microfluidic-based specimen holder. Our video article demonstrates how to assemble and use a microfluidic holder to image liquid specimens within a TEM. In particular, we use simian rotavirus double-layered particles (DLPs) as our model system. We also describe steps to coat the surface of the liquid chamber with affinity biofilms that tether DLPs to the viewing window. This permits us to image assemblies in a manner that is suitable for 3D structure determination. Thus, we present a first glimpse of subviral particles in a native liquid environment.

In situ TEM of Biological Assemblies in Liquid

Here we describe a procedure to image viral complexes in liquid at nanometer resolution using a transmission electron microscope.

就地 液体生物组件的 TEM

Researchers regularly use Transmission Electron Microscopes (TEMs) to examine biological entities and to assess new materials. Here, we describe an ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

光诱导的宏观振荡运动液晶网络的制备

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

工程学

Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.

We have devised a method for low-cost and rapid prototyping of liquid elastomer rubber injection molded devices by using fused deposition modeling 3D printers for mold design and a modified desiccator as a liquid injection system.

医疗器械的使用3D印刷模具的液体注射成型快速，低成本原型

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using ...

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational spectroscopy and time-resolved electron diffraction. Liquid crystal phase is an important state of matter that exists between the solid and liquid phases and it is common in natural systems as well as in organic electronics. Liquid crystals are orientationally ordered but loosely packed, and therefore, the internal conformations and alignments of the molecular components of LCs can be modified by external stimuli. Although advanced time-resolved diffraction techniques have revealed picosecond-scale molecular dynamics of single crystals and polycrystals, direct observations of packing structures and ultrafast dynamics of soft materials have been hampered by blurry diffraction patterns. Here, we report time-resolved IR vibrational spectroscopy and electron diffractometry to acquire ultrafast snapshots of a columnar LC material bearing a photoactive core moiety. Differential-detection analyses of the combination of time-resolved IR vibrational spectroscopy and electron diffraction are powerful tools for characterizing structures and photoinduced dynamics of soft materials.

Here, we present the protocols of differential-detection analyses of time-resolved infrared vibrational spectroscopy and electron diffraction which enable observations of the deformations of local structures around photoexcited molecules in a columnar liquid crystal, giving an atomic perspective on the relationship between the structure and the dynamics of this photoactive material.

观测 Photoresponsive 液晶结构动力学的新方法

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational ...

Microfluidic Preparation of Liquid Crystalline Elastomer Actuators

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation usually consists in the formation of droplets containing low molar mass liquid crystals at elevated temperatures. Subsequently, these particle precursors are oriented in the flow field of the capillary and solidified by a crosslinking polymerization, which produces the final actuating particles. The optimization of the process is necessary to obtain the actuating particles and the proper variation of the process parameters (temperature and flow rate) and allows variations of size and shape (from oblate to strongly prolate morphologies) as well as the magnitude of actuation. In addition, it is possible to vary the type of actuation from elongation to contraction depending on the director profile induced to the droplets during the flow in the capillary, which again depends on the microfluidic process and its parameters. Furthermore, particles of more complex shapes, like core-shell structures or Janus particles, can be prepared by adjusting the setup. By the variation of the chemical structure and the mode of crosslinking (solidification) of the liquid crystalline elastomer, it is also possible to prepare actuating particles triggered by heat or UV-vis irradiation.

This article describes the microfluidic process and parameters to prepare actuating particles from liquid crystalline elastomers. This process allows the preparation of actuating particles and the variation of their size and shape (from oblate to strongly prolate, core-shell, and Janus morphologies) as well as the magnitude of actuation.

液晶弹性体致动器的微流控制备

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation ...

Generation of Scalable, Metallic High-Aspect Ratio Nanocomposites in a Biological Liquid Medium

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper and cystine, with either copper nanoparticles (CNPs) or copper sulfate contributing the metallic component. Synthesis is carried out in liquid under biological conditions (37 &#176;C) and the self-assembled composites form after 24 hr. Once formed, these composites are highly stable in both liquid media and in a dried form. The composites scale from the nano- to micro- range in length, and from a few microns to 25 nm in diameter. Field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) demonstrated that sulfur was present in the NP-derived linear structures, while it was absent from the starting CNP material, thus confirming cystine as the source of sulfur in the final nanocomposites. During synthesis of these linear nano- and micro-composites, a diverse range of lengths of structures is formed in the synthesis vessel. Sonication of the liquid mixture after synthesis was demonstrated to assist in controlling average size of the structures by diminishing the average length with increased time of sonication. Since the formed structures are highly stable, do not agglomerate, and are formed in liquid phase, centrifugation may also be used to assist in concentrating and segregating formed composites.

Here we present a protocol to synthesize novel, high-aspect ratio biocomposites under biological conditions and in liquid media. The biocomposites scale from nanometers to micrometers in diameter and length, respectively. Copper nanoparticles (CNPs) and copper sulfate combined with cystine are the key components for the synthesis.

可扩展的，金属的高宽比纳米复合材料在生物液体中产生

The goal of this protocol is to describe the synthesis of two novel biocomposites with high-aspect ratio structures. The biocomposites consist of copper ...

Synthesis of Biocompatible Liquid Crystal Elastomer Foams as Cell Scaffolds for 3D Spatial Cell Cultures

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block co-polymers featuring cholesterol units as side-chain pendant groups, resulting in smectic-A (SmA) liquid crystal elastomers (LCEs). Foam-like scaffolds, prepared using metal templates, feature interconnected microchannels, making them suitable as 3D cell culture scaffolds. The combined properties of the regular structure of the metal foam and of the elastomer result in a 3D cell scaffold that promotes not only higher cell proliferation compared to conventional porous templated films, but also better management of mass transport (i.e., nutrients, gases, waste, etc.). The nature of the metal template allows for the easy manipulation of foam shapes (i.e., rolls or films) and for the preparation of scaffolds of different pore sizes for different cell studies while preserving the interconnected porous nature of the template. The etching process does not affect the chemistry of the elastomers, preserving their biocompatible and biodegradable nature. We show that these smectic LCEs, when grown for extensive time periods, enable the study of clinically relevant and complex tissue constructs while promoting the growth and proliferation of cells.

This study presents a methodology to prepare 3D, biodegradable, foam-like cell scaffolds based on biocompatible side-chain liquid crystal elastomers (LCEs). Confocal microscopy experiments show that foam-like LCEs allow for cell attachment, proliferation, and the spontaneous alignment of C2C12s myoblasts.

生物相容的液晶弹性体泡沫的合成中用作细胞支架的三维空间细胞培养

Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block ...

单域液晶的弹性体和液晶橡胶纳米复合材料的制备

摘要

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此视频中的章节

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

有针对性的稳定同位素稀释液相色谱 - 质谱法分析细胞脂质提取

的可编程主链液晶性弹性体用双级硫醇丙烯酸酯反应合成

就地液体生物组件的 TEM

光诱导的宏观振荡运动液晶网络的制备

医疗器械的使用3D印刷模具的液体注射成型快速，低成本原型

观测 Photoresponsive 液晶结构动力学的新方法

液晶弹性体致动器的微流控制备

可扩展的，金属的高宽比纳米复合材料在生物液体中产生

生物相容的液晶弹性体泡沫的合成中用作细胞支架的三维空间细胞培养

单域液晶的弹性体和液晶橡胶纳米复合材料的制备

摘要

探索更多视频

此视频中的章节

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

有针对性的稳定同位素稀释液相色谱 - 质谱法分析细胞脂质提取

的可编程主链液晶性弹性体用双级硫醇丙烯酸酯反应合成

就地 液体生物组件的 TEM

光诱导的宏观振荡运动液晶网络的制备

医疗器械的使用3D印刷模具的液体注射成型快速，低成本原型

观测 Photoresponsive 液晶结构动力学的新方法

液晶弹性体致动器的微流控制备

可扩展的，金属的高宽比纳米复合材料在生物液体中产生

生物相容的液晶弹性体泡沫的合成中用作细胞支架的三维空间细胞培养

就地液体生物组件的 TEM