Name: fabrication of a bioactive, pcl-based "self-fitting" shape memory polymer scaffold
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作者感谢得克萨斯州A与M大学工程试验站（TEES）对这项研究的财政支持。林赛指甲非常感谢来自得克萨斯州A与M大学路易斯·斯托克斯联盟少数人参与（LSAMP）和美国国家科学基金会（NSF）研究生研究奖学金计划（GRFP）的支持。张大伟感谢得克萨斯州A与M大学论文奖学金。

1.合成PCL-DA大分子单体<ol><li>运行丙烯酸酯化反应。 <ol><li>重20克的PCL二醇（Mn为=〜10,000g / mol的）的成250ml圆底烧瓶装配有聚四氟乙烯覆盖的磁力搅拌棒。 </li><li>化解PCL二醇在DCM。 <ol><li>添加120 mLlof DCM至烧瓶（浓度= 0.17克/毫升）。 </li><li>放置一个橡胶隔膜松散到烧瓶的颈部，以避免压力积聚，同时也防止DCM中蒸发。 </li><li>在〜250rpm下为约30分钟搅动溶液以完全溶解聚合物。 </li></ol></li><li>添加〜6.6​​毫克的4-二甲基氨基吡啶（DMAP）到溶液中，溶解并搅拌。 </li><li>放置一个橡胶隔膜牢固地插入烧瓶颈部。让溶液继续搅拌。 </li><li>通过橡胶隔膜，轻轻用正的 N 2压力针入口和一开放针吹扫烧瓶用N 2〜3分钟作为出口。 </li><li>取出N 2入口和出口。 </li><li>通过配备有穿过橡胶隔片插入一针的玻璃注射器添加0.56毫升（4.0毫摩尔）三乙胺（的Et 3 N）的溶液。 </li><li>通过配备有穿过橡胶隔片插入一针的玻璃注射器添加0.65 ml的丙烯酰氯滴加（8.0毫摩尔）。 </li><li>返回的 N 2入口到烧瓶中，并允许内容物在正N 2压力搅拌〜30分钟。 </li><li>预加热的油浴至55ºC。 </li><li>所分配的〜30分钟后，除去N 2入口和有冷凝器替换隔膜。 </li><li>淹没烧瓶到预加热的油浴中。 </li><li>允许烧瓶的内容物搅拌20小时。 </li><li>所分配的20小时后，除去从油浴中的烧瓶中，并允许内容​​物冷却至室温。 </li><li>使用旋转蒸发器，从烧瓶中除去DCM溶剂。 </li></ol></li><li> Purify粗PCL-DA产品。 <ol><li>向该烧瓶中，添加〜135毫升乙酸乙酯和溶解粗的PCL-DA。 </li><li>重力过滤通过滤纸将溶液倒入干净250ml圆底烧瓶中。 （注:溶液可增稠在滤纸上，不容易穿过如果是这样，仔细地施加温和热用加热枪。） </li><li>使用旋转蒸发器，除去乙酸乙酯从烧瓶溶剂。 </li><li>向该烧瓶中，添加140〜毫升DCM并溶解粗的PCL-DA。 </li><li>传送内容至500ml分液漏斗中。 </li><li>到漏斗中，添加13.5毫升2M碳酸钾（K 2 CO 3）。 </li><li>盖上漏斗。轻轻倒置漏斗和打旋轻轻一次或两次，照顾经由旋塞以释放压力混合两层。重复3次。 </li><li>替换用一层石蜡膜的盖，并允许该混合物分离O / N（〜12小时）。 </li><li>收集底部或加尼奇层放入250毫升锥形瓶中。 </li><li>添加〜5克无水硫酸镁（ 硫酸镁 ）到烧瓶中，轻轻地旋转。 </li><li>重力过滤通过定性滤纸和到一个干净的250ml圆底烧瓶中的混合物。 </li><li>使用旋转蒸发器，从烧瓶中除去DCM溶剂。 </li><li>在高真空下干​​燥，以除去残留的DCM。 （注:PCL-DA应避光保存。） </li><li>确认丙烯酸化用 1 H-NMR 22,23。 </li></ol></li></ol> 2.准备SMP脚手架（图1） <ol><li>制备熔盐模板。 <ol><li>使用425微米的筛子，直径获得的氯化钠（盐）颗粒〜460±70微米。 （注:平均粒径可以由扫描电子显微镜[SEM]图片包含的ImageJ软件确认。）14 </li><li>向3毫升的玻璃小瓶（ID = 12.9Hz MM），添加1.8克本预先过筛的NaCl。 </li><li>慢慢添加，分四份，7.5重量％（基于重量盐）去离子水（0.146克）到小瓶中。混合通过加入水每个部分的后一个金属刮刀。 </li><li>帽小瓶中，包裹在组织和放置垂直插入一个离心管中。离心15分钟，在3220×g下。 </li><li>取下盖子，让空气干燥O / N（〜12小时）。 </li></ol></li><li>在一个新的玻璃小瓶，准备了"单体溶液"相结合，0.15克每毫升DCM的PCL-DA的。 （注意:对于一种脚手架，〜1毫升溶液应制备）盖上盖子并混合溶液在高速在涡旋混合器上为约1分钟。 </li><li>在一个新的3毫升玻璃小瓶中，准备基于10重量％的2,2-二甲氧基-2-苯基苯乙酮（DMP）中的1-乙烯基-2-吡咯烷酮（NVP）一个"光引发剂溶液"。结合0.115克DMP在1ml的NVP。 （注:其一支架，〜180微升是必需的。）帽，包装在铝箔（阻挡光）和混合解决方案，在高速上的旋涡混合器对于〜1分钟。 （注意:如果在先进制备，该溶液应冷藏并避光。） </li><li>包裹含有大分子单体溶液（不包括帽）用铝箔小瓶（方框光），并通过移液管添加15体积％（基于大分子单体溶液的总体积）的光引发剂的溶液。盖上盖子并混合溶液在高速在涡旋混合器上为约1分钟。 </li><li>用铝箔包装含有熔融盐模板（不包括帽）小瓶（方框光），并通过移液管添加预先制备的大分子单体/引发剂溶液（〜0.6 ml或直到模板被完全覆盖）。 </li><li>帽小瓶中，包裹在组织和放置垂直插入一个离心管中。离心10分钟，在1260×g离心来分发整个模板的大分子单体溶液。 </li><li>取下铝箔，开盖小瓶并暴露于UV光（365纳米，25瓦）下3分钟。风干O / N。 </li><li>删除"含盐的scaffol从具有得分和压裂玻璃瓶后上方镊子小瓶D"。 </li><li>在400毫升烧杯中，准备约200毫升水/乙醇溶剂（1:1体积:体积）。 </li><li>保持浸没在水/乙醇溶剂4天每日溶剂改变该支架。 </li><li>取下溶剂，空气干燥O / N的支架。 </li></ol> 3.应用聚多巴胺涂层以SMP脚手架（图1） <ol><li>在400毫升烧杯中装配有聚四氟乙烯覆盖搅拌棒，准备约200毫升的盐酸多巴胺溶液（在10mM Tris缓冲液2毫克/毫升，pH值= 8.5，25℃）。在搅拌〜150转。 </li><li>一半的距离通过该支架到所述支架，〜;放置一个一次性针（表= 20长度= 40毫米）。环绕所述针毂的线材。 </li><li>由锚定线到烧杯的边缘淹没该支架（与溶液表面上方的针毂）加入搅拌中的多巴胺溶液。 </li><li>通过将注射器插入针毂，并用它拉空气从支架的脱气脚手架。 （注:除气完成时，没有更多的空气可以被除去，该溶液已完全渗入该支架。） </li><li>保持浸没在16小时的搅拌多巴胺溶液中的脚手架。 </li><li>从溶液中除去所述支架和取出针。用DI水和干燥，在真空烘箱中在室温放置24小时冲洗。 </li><li>放置在一个85ºC烘箱该支架1小时。 </li><li>让脚手架冷却至室温。最终的圆柱形支架会〜6毫米直径×约5毫米的高度。 </li></ol> 4.评估"自我装配"行为<ol><li>制作"不规则CMF缺陷模型"使用硬质塑料，其厚度为约5毫米的片材。使用钻头来创建塑料片内的空隙，平均直径大于〜6毫米略少，这表现在图2A中。 </li><li>在AB埃克，热DI水（相当于本临床使用生理盐水）至〜60℃的高温。 </li><li>放置支架到烧杯〜60ºC水。使用镊子推水面下的脚手架，露出所有区域到水中。继续为〜2分钟或直到支架是明显软化（ 图2B）。 </li><li>取下烧杯中的脚手架，并立即按下（手动）到模型的缺陷。 </li><li>允许冷却至室温（〜5-10分钟）（图2C）。 </li><li>从缺陷除去以观察新的，固定的临时形状和相对更刚性的状态（图2D）的返回。 </li></ol> 5.测试形状记忆行为<ol><li>使用动态机械分析仪（DMA;例如TA仪器Q800如本文所用），运行在支架一个应变控制环状热机械压缩测试超过两个周期（N），来确定形状固定性（R f）和形状恢复（R R）（ 图3）。 <ol><li>平衡至60℃（T 高 ）5分钟。 </li><li>压缩到最大应变（ε 米 = 50％）以50％/分钟。 </li><li>保持在ε 米（5分钟）。 </li><li>冷却至25℃（T 低 ），并保持10分钟以固定暂时形状。 </li><li>除去负载。 </li><li>测量在无压力状态下的极限应变（εU）。 </li><li>再加热至60℃（T 高 ），并且维持10分钟，以恢复永久形状。 </li><li>测量回收的应变（εp）的 。 </li><li>同时仍然在60℃（T 高 ），由支架压缩到第 1次循环后回收的高度（N = 1）的50％开始第 2次循环（2 N =）。 </li><li>重复5.1.3-5.1.8对于N = 2。 </li><li>使用以下公式计算R f和R r表示 ，N = 1和2: 的 R F（N）= [εU（N）/εM] R R（N）= [ε 米- εP（N）] / [ε 米- εP（N-1）] </li></ol></li></ol> 6，可视化孔径和孔互连性<ol><li>使用扫描电子显微镜（SEM;例如一个FEI广达SEM如本文所用），观察孔径和孔互连性。 <ol><li>利用镊子以保持SMP支架，淹没在液体N 2 1分钟。 </li><li>从液体的 N 2和断裂以及一个干净的刀片支架的中间除去。 </li><li>使用碳纤维带，加盖SMP支架半一到样品舞台断裂面朝上。 </li><li>溅射涂层与金铂（〜4纳米）。 </li><li>捕获SEM图像在10-15千伏（图4A）推荐的加速电压。 </li></ol></li></ol> 7.测试其体外生物活性的<ol><li>到50毫升离心管中，加入约30毫升1X SBF 24。 </li><li>获得在其原始的，圆筒状成型永久形状的支架。切用干净的刀片一半的支架（跨圆边）。 </li><li>放置一个单独的支架一半到准备好的离心管和帽。 </li><li>保持所述管在37℃下在无SBF更改静态条件下的水浴。 </li><li> 14天后，取出从SBF和空气干燥的支架24小时。 </li><li>使用碳纤维带，加盖支​​架上的断裂面朝上的样品台。 </li><li>溅射涂层与金铂（〜4纳米）。 </li><li>捕获的SEM图像在重赞扬10-15千伏（ 图4B）加速电压。 </li></ol>

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	<li>Neovius, E., Engstrand, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Craniofacial+reconstruction+with+bone+and+biomaterials:+review+over+the+last+11+years.">Craniofacial reconstruction with bone and biomaterials: review over the last 11 years.</a> J Plast Reconstr Aesthet Surg. 63, 1615-1623 (2010).</li><li>Elsalanty, M. E., Genecov, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+grafts+in+craniofacial+surgery.">Bone grafts in craniofacial surgery.</a> Craniomaxillofac Trauma Reconstr. 2, 125-134 (2009).</li><li>Hollister, S. J., 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=Engineering+craniofacial+scaffolds.">Engineering craniofacial scaffolds.</a> Orthod Craniofacial Res. 8, 162-173 (2005).</li><li>Albrektsson, T., Johansson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteoinduction,+osteoconduction+and+osseointegration.">Osteoinduction, osteoconduction and osseointegration.</a> Eur Spine J. 10, S96-S101 (2001).</li><li>Blokhuis, T. J., Arts, J. J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioactive+and+osteoinductive+bone+graft+substitutes:+Definitions,+facts+and+myths.">Bioactive and osteoinductive bone graft substitutes: Definitions, facts and myths.</a> Injury. 42, S26-S29 (1016).</li><li>Zhang, D., 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=A+bioactive+&#8220;self-fitting&#8221;+shape+memory+polymer+scaffold+with+potential+to+treat+cranio-maxillo+facial+bone+defects.">A bioactive &#8220;self-fitting&#8221; shape memory polymer scaffold with potential to treat cranio-maxillo facial bone defects.</a> Acta Biomater. 10, 4597-4605 (2014).</li><li>Lendlein, A., Kelch, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape-memory+polymers.">Shape-memory polymers.</a> Angew. Chem. Int. Ed. 41, 2034-2057 (2002).</li><li>Hu, J., Zhu, Y., Huang, H., Lu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+shape-memory+polymers:+Structure,+mechanism,+functionality,+modeling+and+applications.">Recent advances in shape-memory polymers: Structure, mechanism, functionality, modeling and applications.</a> Prog Polym Sci. 37, 1720-1763 (2012).</li><li>Middleton, J. C., Tipton, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+biodegradable+polymers+as+orthopedic+devices.">Synthetic biodegradable polymers as orthopedic devices.</a> Biomaterials. 21, 2335-2346 (2000).</li><li>Sun, H., Mei, L., Song, C., Cui, X., Wang, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+in+vivo+degradation,+absorption+and+excretion+of+PCL-based+implant.">The in vivo degradation, absorption and excretion of PCL-based implant.</a> Biomaterials. 27, 1735-1740 (2006).</li><li>Woodruff, M. A., Hutmacher, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+return+of+a+forgotten+polymer-Polycaprolactone+in+the+21st+century.">The return of a forgotten polymer-Polycaprolactone in the 21st century.</a> Prog Polym Sci. 35, 1217-1256 (2010).</li><li>Wang, S., Lu, L., Gruetzmacher, J. A., Currier, B. L., Yaszemski, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+characterizations+of+biodegradable+and+crosslinkable+poly(&#949;-caprolactone+fumarate),+poly(ethylene+glycol+fumarate),+and+their+amphiphilic+copolymer.">Synthesis and characterizations of biodegradable and crosslinkable poly(&#949;-caprolactone fumarate), poly(ethylene glycol fumarate), and their amphiphilic copolymer.</a> Biomaterials. 27, 832-841 (2006).</li><li>Zhang, D., Petersen, K. M., Grunlan, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inorganic-organic+shape+memory+polymer+(SMP)+foams+with+highly+tunable+properties.">Inorganic-organic shape memory polymer (SMP) foams with highly tunable properties.</a> ACS Appl Mater Interfaces. 5, 186-191 (2012).</li><li>Zhang, D., Burkes, W. L., Schoener, C. A., Grunlan, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Porous+inorganic-organic+shape+memory+polymers.">Porous inorganic-organic shape memory polymers.</a> Polymer. 53, 2935-2941 (2012).</li><li>Van der Stok, J., Van Lieshout, E. M., El-Massoudi, Y., Van Kralingen, G. H., Patka, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+substitutes+in+the+Netherlands-a+systematic+literature+review.">Bone substitutes in the Netherlands-a systematic literature review.</a> Acta Biomater. 7, 739-750 (2011).</li><li>Lee, H., Dellatore, S. M., Miller, W. M., Messersmith, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mussel-inspired+surface+chemistry+for+multifunctional+coatings.">Mussel-inspired surface chemistry for multifunctional coatings.</a> Science. 318, 426-430 (2007).</li><li>Hong, S., 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=Non-covalent+self-assembly+and+covalent+polymerization+co-contribute+to+polydopamine+formation.">Non-covalent self-assembly and covalent polymerization co-contribute to polydopamine formation.</a> Adv Funct Mater. 22, 4711-4717 (2012).</li><li>Ryu, J., Ku, S. H., Lee, H., Park, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mussel-inspired+polydopamine+coating+as+a+universal+route+to+hydroxyapatite+crystallization.">Mussel-inspired polydopamine coating as a universal route to hydroxyapatite crystallization.</a> Adv Funct Mater. 20, 2132-2139 (2010).</li><li>Lee, Y. B., 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=Polydopamine-mediated+immobilization+of+multiple+bioactive+molecules+for+the+development+of+functional+vascular+graft+materials.">Polydopamine-mediated immobilization of multiple bioactive molecules for the development of functional vascular graft materials.</a> Biomaterials. 33, 8343-8352 (2012).</li><li>Wu, C., Fan, W., Chang, J., Xiao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mussel-inspired+porous+SiO+2+scaffolds+with+improved+mineralization+and+cytocompatibility+for+drug+delivery+and+bone+tissue+engineering.">Mussel-inspired porous SiO 2 scaffolds with improved mineralization and cytocompatibility for drug delivery and bone tissue engineering.</a> J Mater Chem. 21, 18300-18307 (2011).</li><li>Ku, S. H., Ryu, J., Hong, S. K., Lee, H., Park, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=General+functionalization+route+for+cell+adhesion+on+non-wetting+surfaces.">General functionalization route for cell adhesion on non-wetting surfaces.</a> Biomaterials. 31, 2535-2541 (2010).</li><li>Schoener, C. A., Weyand, C. B., Murthy, R., Grunlan, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape+memory+polymers+with+silicon-containing+segments.">Shape memory polymers with silicon-containing segments.</a> J Mater Chem. 20, 1787-1793 (2010).</li><li>Zhang, D., Giese, M. L., Prukop, S. L., Grunlan, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly(&#949;-caprolactone)-based+shape+memory+polymers+with+variable+polydimethylsiloxane+soft+segment+lengths.">Poly(&#949;-caprolactone)-based shape memory polymers with variable polydimethylsiloxane soft segment lengths.</a> J Polym Sci Pol Chem. 49, 754-761 (2011).</li><li>Kokubo, T., Takadama, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+useful+is+SBF+in+predicting+in+vivo+bone+bioactivity.">How useful is SBF in predicting in vivo bone bioactivity.</a> Biomaterials. 27, 2907-2915 (2006).</li><li>Murphy, W. L., Dennis, R. G., Kileny, J. L., Mooney, 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=Salt+fusion:+an+approach+to+improve+pore+interconnectivity+within+tissue+engineering+scaffolds.">Salt fusion: an approach to improve pore interconnectivity within tissue engineering scaffolds.</a> Tissue Eng. 8, 43-52 (2002).</li><li>Yang, Q., Chen, L., Shen, X., Tan, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+polycaprolactone+tissue+engineering+scaffolds+by+improved+solvent+casting/particulate+leaching+method.">Preparation of polycaprolactone tissue engineering scaffolds by improved solvent casting/particulate leaching method.</a> J Macromol Sci Phys. 45, 1171-1181 (2006).</li><li>Madbouly, S. A., Kratz, K., Klein, F., L&#252;zow, K., Lendlein, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermomechanical+behaviour+of+biodegradable+shape-memory+polymer+foams.">Thermomechanical behaviour of biodegradable shape-memory polymer foams.</a> 1190, (2009).</li><li>Luo, X., Mather, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+characterization+of+shape+memory+elastomeric+composites.">Preparation and characterization of shape memory elastomeric composites.</a> Macromolecules. 42, 7251-7253 (2009).</li><li>Lendlein, A., Schmidt, A. M., Langer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AB-polymer+networks+based+on+oligo(&#603;-caprolactone)+segments+showing+shape-memory+properties.">AB-polymer networks based on oligo(&#603;-caprolactone) segments showing shape-memory properties.</a> Proc Natl Acad Sci. 98, 842-847 (2001).</li></ol>

The authors have nothing to disclose.

这个协议描述了一种聚多巴胺涂覆的，PCL-基于支架，其自入行为的制备，以及骨诱导性和生物活性，使得在不规则CMF骨缺损的治疗兴趣它。该协议的各方面可以被改变，以改变各种支架功能。 该协议开始于PCL二醇，允许UV固化的丙烯酸酯化。在所报告的实例中，PCL二醇Mn为是〜10,000g / mol的。然而，通过适当地调整丙烯酰氯量和的Et 3 N的PCL-DA了PCL二醇可以被用?...

目前考虑的颅颌面（CMF）骨缺损治疗的金标准，收获的自体移植的移植是由复杂的移植手术，供体部位发病率和有限1阻碍。一个特别困难被整形并紧紧固定在刚性移植到缺陷，以获得骨整合和预防移植物吸收。组织工程已被调查作为一种替代战略，以自体移植和人工合成骨替代品（ 如骨水泥）2,3。关键的组织工程方法的成功是一组特定属性的支架。第一，为了实现骨整合，支架必须形成与相邻的骨组织4紧密接触。该支架也应该是骨传导，允许细胞迁移，营养扩散和neotissue沉积4,5。这种行为通常是实现了与可生物降解的SCAffolds表现出高度互联的孔结构。最后，该支架应的生物活性，以促进融合和粘接与周围骨组织5。 在这里，我们提出了一个协议，准备组织工程支架具有这些属性。重要的是，这种支架显示能力的"自我适应"到，由于其形状记忆行为6不规则的CMF缺陷。温敏形状记忆聚合物（SMP系统）是已知的在暴露于经受形状改变以加热7,8。中小事务所是由"netpoints"（即化学或物理交联），这决定了永久的形状和"转换段"，它保持暂时形状，并恢复永久的形状。开关段表现出相应于任一所述的玻璃化转变（T 克 ）热转变温度（T 反式）或熔融聚合物的转变（Tm值）。由于其结果，污水收集可以顺序变形为暂时形状在T&gt; T 反式，在T &lt;T 反式固定在暂时形状，并恢复到在T&gt; T 反式的永久形状。因此，SMP支架可以实现"自我装配"中的CMF缺陷如下6。曝光后，以温盐水（T&gt; T 转 ），一个SMP支架将成为延展性，允许一个一般制造的圆筒状的支架是用手压成不规则的缺陷，具有形状恢复促进扩大脚手架的缺陷边界。在冷却（T &lt;T 反式），脚手架将回到其相对更为刚性的状态，具有形状固定性保持缺陷在其新的临时形状。在这个协议中，将SMP支架选自聚己内酯（PCL）中制备，可生物降解的聚合物广泛研究的组织再生和其它生物医学应用9-11。对于形状记忆，日PCL电子Tm值用作经t 反式和43之后60°C之间变化，取决于在PCL 12的分子量。在这个协议中，支架的Ť 反式 （即Tm值）是56.6±0.3ºC6。 为了达到骨传导性，协议的开发，使PCL基的SMP支架与基于溶剂的铸造颗粒淋（SCPL）方法6,13,14高度互连的孔。聚己内酯丙烯酸酯（PCL-DA）（Mn为=〜10,000g / mol的）得到使用，以允许快速，光化学交联和溶解于二氯甲烷（DCM），以允许溶剂浇铸在盐模板。以下光化学固化和溶剂蒸发，盐模板除去浸出到水中。平均盐大小调节支架孔径。重要的是，该盐模板融合用水之前溶剂浇铸实现孔隙interconnectiviTY。 生物活性传授给了SMP的支架原位形成聚多巴胺涂到孔壁6。生物活性通常通过包含玻璃或玻璃-陶瓷填料15引入到支架。但是，这些可能引起不必要的易碎的机械性能。多巴胺已经显示，以形成对各种基材16-19中粘附，薄聚多巴胺层。在这个协议中，将SMP支架进行多巴胺的弱碱性溶液（pH = 8.5），以形成聚多巴胺的所有孔壁表面6 nanothick涂层。除了 ​​增强表面的亲水性以改进细胞粘附和传播，聚多巴胺已被证明是生物活性在形成的羟基磷灰石（HAP）在暴露于模拟体液（SBF）18,20,21的条款。在最后的步骤，将涂覆的支架被暴露在85℃（T&gt;Ť 反式）的wh热处理ICH导致脚手架致密化。热处理是前面提到的是为支架的形状记忆行为所必需的，或许是由于PCL结晶 ​​区域重组，以更接近14。 我们另外描述的方法中的不规则缺陷模型的自装配行为表征，形状记忆行为而言 ​​应变控制环状热机械压缩试验（即形状恢复和形状固定性），孔的形态，并在体外生物活性 。策略定制支架性能也提出了。

<table><tbody><tr><td>Polycaprolactone-diol (Mn ~ 10,000 g/mol)</td><td>Sigma-Aldrich</td><td>440752</td><td></td></tr><tr><td>Dichloromethane (DCM)</td><td>Sigma-Aldrich</td><td>D65100</td><td>Dried over 4A molecular sieves</td></tr><tr><td>4-dimethylaminopyridine (DMAP)</td><td>Sigma-Aldrich</td><td>D5640</td><td></td></tr><tr><td>Triethylamine (Et3N)</td><td>Sigma-Aldrich</td><td>T0886</td><td></td></tr><tr><td>Acryloyl chloride</td><td>Sigma-Aldrich</td><td>A24109</td><td></td></tr><tr><td>Ethyl acetate</td><td>Sigma-Aldrich</td><td>319902</td><td></td></tr><tr><td>Potassium carbonate (K2CO3)</td><td>Sigma-Aldrich</td><td>209619</td><td></td></tr><tr><td>Anhydrous magnesium sulfate (MgSO4)</td><td>Fisher</td><td>M65</td><td></td></tr><tr><td>Sodium chloride (NaCl)</td><td>Sigma-Aldrich</td><td>S9888</td><td></td></tr><tr><td>2,2-dimethoxy-2-phenyl acetophenone (DMP)</td><td>Sigma-Aldrich</td><td>196118</td><td></td></tr><tr><td>1-vinyl-2-pyrrolidinone (NVP)</td><td>Sigma-Aldrich</td><td>V3409</td><td></td></tr><tr><td>Ethanol</td><td>Sigma-Aldrich</td><td>459844</td><td></td></tr><tr><td>Dopamine hydrochloride</td><td>Sigma-Aldrich</td><td>H8502</td><td></td></tr><tr><td>Tris buffer (2mol/L)</td><td>Fisher</td><td>BP1759</td><td>Used at 10 mM concentration, pH = 8.5</td></tr><tr><td>Sieve</td><td>VWR</td><td>47729-972</td><td></td></tr><tr><td>UV-Transilluminator (365 nm, 25 W)</td><td>UVP</td><td>95-0426-02</td><td></td></tr><tr><td>Centrifuge</td><td>Eppendorf</td><td>5810 R</td><td></td></tr><tr><td>Dynamic Mechanical Analyzer (DMA)</td><td>TA Instruments</td><td>Q800</td><td></td></tr><tr><td>High Resolution Sputter Coater</td><td>Cressington</td><td>208HR</td><td></td></tr><tr><td>Scanning Electron Microscope (SEM)</td><td>FEI</td><td>Quanta 600</td><td></td></tr></tbody></table>

fabrication of a bioactive, pcl-based "self-fitting" shape memory polymer scaffold

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to the success of this approach is a scaffold that is able to conformally fit within an irregular defect while also having the requisite biodegradability, pore interconnectivity and bioactivity. By nature of their shape recovery and fixity properties, shape memory polymer (SMP) scaffolds could achieve defect &#8220;self-fitting.&#8221; In this way, following exposure to warm saline (~60 &#186;C), the SMP scaffold would become malleable, permitting it to be hand-pressed into an irregular defect. Subsequent cooling (~37 &#186;C) would return the scaffold to its relatively rigid state within the defect. To meet these requirements, this protocol describes the preparation of SMP scaffolds prepared via the photochemical cure of biodegradable polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method. A fused salt template is utilized to achieve pore interconnectivity. To realize bioactivity, a polydopamine coating is applied to the surface of the scaffold pore walls. Characterization of self-fitting and shape memory behaviors, pore interconnectivity and in vitro bioactivity are also described.

将所得的PCL基SMP支架是能够自我装配到一个模型CMF缺陷（图2）的。短暂暴露后温热盐水（〜60℃），圆柱形支架软化允许支架进行手动压入并展开模型缺损内。冷却至RT后，支架被固定到被从缺陷保留在除去其新的临时形状。 一个SMP支架材料的形状记忆行为由应变控制环状热机械压缩试验在形状固定性（R f）和形状恢复（R R）（图3）...

Watch this Scientific Journal Video about Fabrication of a Bioactive, PCL-based "Self-fitting" Shape Memory Polymer Scaffold at JoVE.com

Fabrication of a Bioactive, PCL-based "Self-fitting" Shape Memory Polymer Scaffold

Scaffolds capable of fitting within cranio-maxillofacial (CMF) bone defects while exhibiting osteoconductivity and bioactivity are of interest. This protocol describes the preparation of a shape memory scaffold based on polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method employing a fused salt template and application of a bioactive polydopamine coating.

生物活性，PCL为基础的"自我装配"形状记忆聚合物支架的制备

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to ...

fabrication-bioactive-pcl-based-self-fitting-shape-memory-polymer

Research

JoVE Journal

Bioengineering

12.6K 次观看.  Texas A&M University. Scaffolds capable of fitting within cranio-maxillofacial (CMF) bone defects while exhibiting osteoconductivity and bioactivity are of interest. This protocol describes the preparation of a shape memory scaffold based on polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method employing a fused salt template and application of a bioactive polydopamine coating.

视频: Fabrication of a Bioactive, PCL-based "Self-fitting" Shape Memory Polymer Scaffold

Elastomeric PGS Scaffolds in Arterial Tissue Engineering

Cardiovascular disease is one of the leading cause of mortality in the US and especially, coronary artery disease increases with an aging population and increasing obesity1. Currently, bypass surgery using autologous vessels, allografts, and synthetic grafts are known as a commonly used for arterial substitutes2. However, these grafts have limited applications when an inner diameter of arteries is less than 6 mm due to low availability, thrombotic complications, compliance mismatch, and late intimal hyperplasia3,4. To overcome these limitations, tissue engineering has been successfully applied as a promising alternative to develop small-diameter arterial constructs that are nonthrombogenic, robust, and compliant. Several previous studies have developed small-diameter arterial constructs with tri-lamellar structure, excellent mechanical properties and burst pressure comparable to native arteries5,6. While high tensile strength and burst pressure by increasing collagen production from a rigid material or cell sheet scaffold, these constructs still had low elastin production and compliance, which is a major problem to cause graft failure after implantation. Considering these issues, we hypothesized that an elastometric biomaterial combined with mechanical conditioning would provide elasticity and conduct mechanical signals more efficiently to vascular cells, which increase extracellular matrix production and support cellular orientation.
The objective of this report is to introduce a fabrication technique of porous tubular scaffolds and a dynamic mechanical conditioning for applying them to arterial tissue engineering. We used a biodegradable elastomer, poly (glycerol sebacate) (PGS)7 for fabricating porous tubular scaffolds from the salt fusion method. Adult primary baboon smooth muscle cells (SMCs) were seeded on the lumen of scaffolds, which cultured in our designed pulsatile flow bioreactor for 3 weeks. PGS scaffolds had consistent thickness and randomly distributed macro- and micro-pores. Mechanical conditioning from pulsatile flow bioreactor supported SMC orientation and enhanced ECM production in scaffolds. These results suggest that elastomeric scaffolds and mechanical conditioning of bioreactor culture may be a promising method for arterial tissue engineering.

Elastomeric PGS scaffolds with vascular smooth muscle cells cultured in a pulsatile flow bioreactor may lead to promising small-diameter arterial constructs with native ECM production in a relatively short culture period.

弹性PGS的动脉组织工程支架

Cardiovascular disease is one of the leading cause of mortality in the US and especially, coronary artery disease increases with an aging population and ...

科研

生物工程

Shape Memory Polymers for Active Cell Culture

Shape memory polymers (SMPs) are a class of "smart" materials that have the ability to change from a fixed, temporary shape to a pre-determined permanent shape upon the application of a stimulus such as heat1-5. In a typical shape memory cycle, the SMP is first deformed at an elevated temperature that is higher than its transition temperature, Ttrans [either the melting temperature (Tm) or the glass transition temperature (Tg)]. The deformation is elastic in nature and mainly leads to a reduction in conformational entropy of the constituent network chains (following the rubber elasticity theory). The deformed SMP is then cooled to a temperature below its Ttrans while maintaining the external strain or stress constant. During cooling, the material transitions to a more rigid state (semi-crystalline or glassy), which kinetically traps or "freezes" the material in this low-entropy state leading to macroscopic shape fixing. Shape recovery is triggered by continuously heating the material through Ttrans under a stress-free (unconstrained) condition. By allowing the network chains (with regained mobility) to relax to their thermodynamically favored, maximal-entropy state, the material changes from the temporary shape to the permanent shape.
Cells are capable of surveying the mechanical properties of their surrounding environment6. The mechanisms through which mechanical interactions between cells and their physical environment control cell behavior are areas of active research. Substrates of defined topography have emerged as powerful tools in the investigation of these mechanisms. Mesoscale, microscale, and nanoscale patterns of substrate topography have been shown to direct cell alignment, cell adhesion, and cell traction forces7-14. These findings have underscored the potential for substrate topography to control and assay the mechanical interactions between cells and their physical environment during cell culture, but the substrates used to date have generally been passive and could not be programmed to change significantly during culture. This physical stasis has limited the potential of topographic substrates to control cells in culture.
Here, active cell culture (ACC) SMP substrates are introduced that employ surface shape memory to provide programmed control of substrate topography and deformation. These substrates demonstrate the ability to transition from a temporary grooved topography to a second, nearly flat memorized topography. This change in topography can be used to control cell behavior under standard cell culture conditions.

A method for developing cell culture substrates with the ability to change topography during culture is described. The method makes use of smart materials known as shape memory polymers that have the ability to memorize a permanent shape. This concept is adaptable to a wide range of materials and applications.

形状记忆聚合物主动细胞培养

Shape memory polymers (SMPs) are a class of "smart" materials that have the ability to change from a fixed, temporary shape to a pre-determined permanent ...

Postproduction Processing of Electrospun Fibres for Tissue Engineering

Electrospinning is a commonly used and versatile method to produce scaffolds (often biodegradable) for 3D tissue engineering.1, 2, 3 Many tissues in vivo undergo biaxial distension to varying extents such as skin, bladder, pelvic floor and even the hard palate as children grow. In producing scaffolds for these purposes there is a need to develop scaffolds of appropriate biomechanical properties (whether achieved without or with cells) and which are sterile for clinical use. The focus of this paper is not how to establish basic electrospinning parameters (as there is extensive literature on electrospinning) but on how to modify spun scaffolds post production to make them fit for tissue engineering purposes - here thickness, mechanical properties and sterilisation (required for clinical use) are considered and we also describe how cells can be cultured on scaffolds and subjected to biaxial strain to condition them for specific applications.
Electrospinning tends to produce thin sheets; as the electrospinning collector becomes coated with insulating fibres it becomes a poor conductor such that fibres no longer deposit on it. Hence we describe approaches to produce thicker structures by heat or vapour annealing increasing the strength of scaffolds but not necessarily the elasticity. Sequential spinning of scaffolds of different polymers to achieve complex scaffolds is also described. Sterilisation methodologies can adversely affect strength and elasticity of scaffolds. We compare three methods for their effects on the biomechanical properties on electrospun scaffolds of poly lactic-co-glycolic acid (PLGA).
Imaging of cells on scaffolds and assessment of production of extracellular matrix (ECM) proteins by cells on scaffolds is described. Culturing cells on scaffolds in vitro can improve scaffold strength and elasticity but the tissue engineering literature shows that cells often fail to produce appropriate ECM when cultured under static conditions. There are few commercial systems available that allow one to culture cells on scaffolds under dynamic conditioning regimes - one example is the Bose Electroforce 3100 which can be used to exert a conditioning programme on cells in scaffolds held using mechanical grips within a media filled chamber.4 An approach to a budget cell culture bioreactor for controlled distortion in 2 dimensions is described. We show that cells can be induced to produce elastin under these conditions. Finally assessment of the biomechanical properties of processed scaffolds cultured with or without cells is described.

Electrospun scaffolds can be processed post production for tissue engineering applications. Here we describe methods for spinning complex scaffolds (by consecutive spinning), for making thicker scaffolds (by multi-layering using heat or vapour annealing), for achieving sterility (aseptic production or sterilisation post production) and for achieving appropriate biomechanical properties.

静电纤维组织工程的后期处理

Electrospinning is a commonly used and versatile method to produce  scaffolds (often biodegradable) for 3D tissue engineering.1, 2, 3 Many tissues in vivo ...

Composite Scaffolds of Interfacial Polyelectrolyte Fibers for Temporally Controlled Release of Biomolecules

Various scaffolds used in tissue engineering require a controlled biochemical environment to mimic the physiological cell niche. Interfacial polyelectrolyte complexation (IPC) fibers can be used for controlled delivery of various biological agents such as small molecule drugs, cells, proteins and growth factors. The simplicity of the methodology in making IPC fibers gives flexibility in its application for controlled biomolecule delivery. Here, we describe a method of incorporating IPC fibers into two different polymeric scaffolds, hydrophilic polysaccharide and hydrophobic polycaprolactone, to create a multi-component composite scaffold. We showed that IPC fibers can be easily embedded into these polymeric structures, enhancing the capability for sustained release and improved preservation of biomolecules. We also created a composite polymeric scaffold with topographical cues and sustained biochemical release that can have synergistic effects on cell behavior. Composite polymeric scaffolds with IPC fibers represent a novel and simple method of recreating the cellular niche.

Scaffolds for tissue engineering need to recapitulate the complex biochemical and biophysical microenvironment of the cellular niche. Here, we show the use of interfacial polyelectrolyte complexation fibers as a platform to create composite, multi-component polymeric scaffolds with sustained biochemical release.

界面聚电解质纤维的生物分子在时间控释复合支架

Various scaffolds used in tissue engineering require a controlled biochemical environment to mimic the physiological cell niche. Interfacial ...

Three-dimensional Biomimetic Technology: Novel Biorubber Creates Defined Micro- and Macro-scale Architectures in Collagen Hydrogels

Tissue scaffolds play a crucial role in the tissue regeneration process. The ideal scaffold must fulfill several requirements such as having proper composition, targeted modulus, and well-defined architectural features. Biomaterials that recapitulate the intrinsic architecture of in vivo tissue are vital for studying diseases as well as to facilitate the regeneration of lost and malformed soft tissue. A novel biofabrication technique was developed which combines state of the art imaging, three-dimensional (3D) printing, and selective enzymatic activity to create a new generation of biomaterials for research and clinical application. The developed material, Bovine Serum Albumin rubber, is reaction injected into a mold that upholds specific geometrical features. This sacrificial material allows the adequate transfer of architectural features to a natural scaffold material. The prototype consists of a 3D collagen scaffold with 4 and 3 mm channels that represent a branched architecture. This paper emphasizes the use of this biofabrication technique for the generation of natural constructs. This protocol utilizes a computer-aided software (CAD) to manufacture a solid mold which will be reaction injected with BSA rubber followed by the enzymatic digestion of the rubber, leaving its architectural features within the scaffold material.

An innovative biofabrication technique was developed to engineer three-dimensional constructs that resemble the architectural features, components, and mechanical properties of in vivo tissue. This technique features a newly developed sacrificial material, BSA rubber, which transfers detailed spatial features, reproducing the in vivo architectures of a wide variety of tissues.

三维仿生技术:新型Biorubber创建自定义微观和宏观尺度架构的胶原凝胶

Tissue scaffolds play a crucial role in the tissue regeneration process. The ideal scaffold must fulfill several requirements such as having proper ...

Synthesis of Thermogelling Poly(N-isopropylacrylamide)-graft-chondroitin Sulfate Composites with Alginate Microparticles for Tissue Engineering

Injectable biomaterials are defined as implantable materials that can be introduced into the body as a liquid and solidify in situ. Such materials offer the clinical advantages of being implanted minimally invasively and easily forming space-filling solids in irregularly shaped defects. Injectable biomaterials have been widely investigated as scaffolds for tissue engineering. However, for the repair of certain load-bearing areas in the body, such as the intervertebral disc, scaffolds should possess adhesive properties. This will minimize the risk of dislocation during motion and ensure intimate contact with the surrounding tissue, providing adequate transmission of forces. Here, we describe the preparation and characterization of a scaffold composed of thermally sensitive poly(N-isopropylacrylamide)-graft-chondroitin sulfate (PNIPAAM-g-CS) and alginate microparticles. The PNIPAAm-g-CS copolymer forms a viscous solution in water at RT, into which alginate particles are suspended to enhance adhesion. Above the lower critical solution temperature (LCST), around 30 &#176;C, the copolymer forms a solid gel around the microparticles. We have adapted standard biomaterials characterization procedures to take into account the reversible phase transition of PNIPAAm-g-CS. Results indicate that the incorporation of 50 or 75 mg/ml&#160;alginate particles into 5% (w/v) PNIPAAm-g-CS solutions quadruple the adhesive tensile strength of PNIPAAm-gCS alone (p&#60;0.05). The incorporation of alginate microparticles also significantly increases swelling capacity of PNIPAAm-g-CS (p&#60;0.05), helping to maintain a space-filling gel within tissue defects. Finally, results of the in vitro toxicology assay kit, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and Live/Dead viability assay indicate that the adhesive is capable of supporting the survival and proliferation of encapsulated Human Embryonic Kidney (HEK) 293 cells over 5 days.

Synthesis of Thermogelling PolyN-isopropylacrylamide-graft-chondroitin Sulfate Composites with Alginate Microparticles for Tissue Engineering

An injectable tissue engineering scaffold composed of poly(N-isopropylacrylamide)-graft-chondroitin sulfate (PNIPAAm-g-CS)-containing alginate microparticles was prepared. The adhesive strength, swelling properties and in vitro biocompatibility are analyzed in this study. The characterization techniques developed here may be applicable to other thermogelling systems.

组织工程热胶凝聚（N-异丙基丙烯酰胺） - 接枝 - 硫酸软骨素复合材料的海藻酸钠微粒的合成

Injectable biomaterials are defined as implantable materials that can be introduced into the body as a liquid and solidify in situ. Such materials offer ...

A Facile and Eco-friendly Route to Fabricate Poly(Lactic Acid) Scaffolds with Graded Pore Size

Over the recent years, functionally graded scaffolds (FGS) gaineda crucial role for manufacturing of devices for tissue engineering. The importance of this new field of biomaterials research is due to the necessity to develop implants capable of mimicking the complex functionality of the various tissues, including a continuous change from one structure or composition to another. In this latter context, one topic of main interest concerns the design of appropriate scaffolds for bone-cartilage interface tissue. In this study, three-layered scaffolds with graded pore size were achieved by melt mixing poly(lactic acid) (PLA), sodium chloride (NaCl) and polyethylene glycol (PEG). Pore size distributions were controlled by NaCl granulometry and PEG solvation. Scaffolds were characterized from a morphological and mechanical point of view. A correlation between the preparation method, the pore architecture and compressive mechanical behavior was found. The interface adhesion strength was quantitatively evaluated by using a custom-designed interfacial strength test. Furthermore, in order to imitate the human physiology, mechanical tests were also performed in phosphate buffered saline (PBS) solution at 37 &#176;C. The method herein presented provides a high control of porosity, pore size distribution and mechanical performance, thus offering the possibility to fabricate three-layered scaffolds with tailored properties by following a simple and eco-friendly route.

A Facile and Eco-friendly Route to Fabricate PolyLactic Acid Scaffolds with Graded Pore Size

In this work, poly(lactic acid)/polyethylene glycol (PLA/PEG) scaffolds were prepared by using a combination of melt mixing and selective leaching. The method herein discussed permitted to develop three-layer scaffolds by highly controlling both porosity and pore size. The mechanical properties were also evaluated in a physiological environment.

的简便和环保路线制造聚乳酸支架与分级孔径

Over the recent years, functionally graded scaffolds (FGS) gaineda crucial role for manufacturing of devices for tissue engineering. The importance of ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

用于组织工程应用的三维聚 (ε-内) 支架的熔体静电纺丝

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Novel Process for 3D Printing Decellularized Matrices

3D bioprinting aims to create custom scaffolds that are biologically active and accommodate the desired size and geometry. A thermoplastic backbone can provide mechanical stability similar to native tissue while biologic agents offer compositional cues to progenitor cells, leading to their migration, proliferation, and differentiation to reconstitute the original tissues/organs1,2. Unfortunately, many 3D printing compatible, bioresorbable polymers (such as polylactic acid, PLA) are printed at temperatures of 210 &#176;C or higher - temperatures that are detrimental to biologics. On the other hand, polycaprolactone (PCL), a different type of polyester, is a bioresorbable, 3D printable material that has a gentler printing temperature of 65 &#176;C. Therefore, it was hypothesized that decellularized extracellular matrix (DM) contained within a thermally protective PLA barrier could be printed within PCL filament and remain in its functional conformation. In this work, osteochondral repair was the application for which the hypothesis was tested. As such, porcine cartilage was decellularized and encapsulated in polylactic acid (PLA) microspheres which were then extruded with polycaprolactone (PCL) into filament to produce 3D constructs via fused deposition modeling. The constructs with or without the microspheres (PLA-DM/PCL and PCL(-), respectively) were evaluated for differences in surface features.

This protocol describes the production of polycaprolactone (PCL) filament with embedded polylactic acid (PLA) microspheres which contain decellularized matrices (DM) for 3D printing of structural tissue engineering constructs.

一种新的三维打印解光矩阵处理方法

3D bioprinting aims to create custom scaffolds that are biologically active and accommodate the desired size and geometry. A thermoplastic backbone can ...

Controlling Electrospun Polymer Morphology for Tissue Engineering Demonstrated Using hepG2 Cell Line

Electrospinning affords researchers the opportunity to fabricate reproducible micro to nanoscale polymer fibers. The 3D fibrous architecture of electrospun polymers is regarded as a structural imitation of the extracellular matrix (ECM). Hence, electrospun fibers fabricated from biocompatible polymers have been widely investigated by tissue engineering researchers for their potential role as an artificial ECM for guiding tissue growth both in vitro and in vivo. All cells are acutely sensitive to their mechanical environment. This has been demonstrated by the discovery of multiple mechanotransduction pathways intrinsically linked to the cytoskeletal actin filaments. The cytoskeleton acts as a mechanical sensor that can direct the functionality and differentiation of the host cell depending on the stiffness and morphology of its substrate. Electrospun fibers can be tuned both in terms of fiber size and morphology to easily modulate the mechanical environment within a fibrous polymer scaffold. Here, methods for electrospinning polycaprolactone (PCL) for three distinct morphologies at two different fiber diameters are described. The morphological fiber categories consist of randomly oriented fibers, aligned fibers, and porous cryogenically spun fibers, with 1 &#181;m and 5 &#181;m diameters. The methods detailed within this study are proposed as a platform for investigating the effect of electrospun fiber architecture on tissue generation. Understanding these effects will allow researchers to optimize the mechanical properties of electrospun fibers and demonstrate the potential of this technology more thoroughly.

This method provides the means to test different polycaprolactone fiber morphologies and topographies for the purpose of tissue engineering. Small and large fibers are fabricated with random orientations, aligned orientations, and also porous cryogenically electrospun structures and used as platforms for cell culture.