Los autores agradecen a Texas A &amp; M University Ingeniería y Estación Experimental (TEE) para el apoyo financiero de esta investigación. Lindsay Nail agradece el apoyo de la Universidad de Texas A &amp; M University Louis Stokes Alianza para la Participación de las Minorías (LSAMP) y la Fundación Nacional de Ciencia (NSF) de Posgrado Programa de Becas de Investigación (GRFP). Dawei Zhang agradece a la Universidad de Texas A &amp; M University Disertación compañerismo.

1. Sintetizar PCL-DA Macrómero <ol><li> Ejecute la reacción acrilación. <ol><li> Pesar 20 g de PCL-diol (M n = ~ 10.000 g / mol) en un matraz de 250 ml de fondo redondo equipado con una barra agitadora magnética de teflón cubierto. </li><li> Disolver el PCL-diol en DCM. <ol><li> Añadir 120 mLlof DCM al matraz (concentración = 0,17 g / ml). </li><li> Colocar un tapón de caucho de manera suelta en el cuello del matraz a fin de evitar la acumulación de presión mientras que también la prevención de la evaporación del DCM. </li><li> Solución del Stir por ~ 30 min a ~ 250 rpm para disolver completamente el polímero. </li></ol></li><li> Añadir ~ 6,6 mg de 4-dimetilaminopiridina (DMAP) a la solución y se disuelve con agitación. </li><li> Colocar un tapón de caucho firmemente en el cuello del matraz. Deje que la solución para continuar la agitación. </li><li> A través del tabique de caucho, purgar suavemente el matraz con N2 durante ~ 3 min utilizando una entrada de N2 aguja de presión positiva y una aguja abiertacomo una salida. </li><li> Retire la entrada y la salida N 2. </li><li> Añadir 0,56 ml (4,0 mmol) de trietilamina (Et 3 N) gota a gota mediante una jeringa de vidrio equipado con una aguja insertada a través del septo de caucho. </li><li> Añadir 0,65 ml (8,0 mmol) de cloruro de acriloílo gota a gota mediante una jeringa de vidrio equipado con una aguja insertada a través del septo de caucho. </li><li> Devolver la entrada de N 2 al matraz y permiten que el contenido en agitación bajo presión positiva de N 2 ~ 30 min. </li><li> Pre-calentar un baño de aceite a 55 ºC. </li><li> Después de que el asignado ~ 30 min, retire la entrada de N 2 y sustituir el septum con un condensador. </li><li> Sumergir el matraz en el baño de aceite precalentado. </li><li> Permitir que el contenido del matraz en agitación durante 20 h. </li><li> Después del 20 hr asignado, retire el matraz del baño de aceite y permiten que los contenidos se enfríen a temperatura ambiente. </li><li> Usando un evaporador rotatorio, retire DCM disolvente del matraz. </li></ol></li><li> Purify el producto PCL-DA crudo. <ol><li> Al matraz, añadir ~ 135 ml de acetato de etilo y se disuelve el crudo PCL-DA. </li><li> Gravedad filtrar la solución a través de papel de filtro en un matraz de fondo redondo de 250 ml limpio. (Nota: La solución puede espesar en el papel de filtro, que no pasa fácilmente a través de ser así, aplicar cuidadosamente calor templado, con una pistola de calor..) </li><li> Usando un evaporador rotatorio, retire acetato de etilo disolvente del matraz. </li><li> Al matraz, añadir ~ 140 ml de DCM y se disuelve el crudo PCL-DA. </li><li> Transferir contenido a una de 500 ml embudo de separación. </li><li> Para el embudo, añadir 13,5 ml de 2 M de carbonato de potasio (K 2 CO 3). </li><li> Tape el embudo. Mezclar suavemente las dos capas invirtiendo el embudo y se agita suavemente una o dos veces, teniendo cuidado para liberar la presión a través de la llave de paso. Repita 3 veces. </li><li> Vuelva a colocar la tapa con una capa de Parafilm y permitir que la mezcla se separe O / N (~ 12 h). </li><li> Recoge la parte inferior, ocapa ganic en un matraz Erlenmeyer de 250 ml. </li><li> Añadir ~ 5 g de sulfato de magnesio anhidro (MgSO4) al matraz y agitar suavemente. </li><li> Gravedad filtrar la mezcla a través de papel de filtro cualitativo y en un lugar limpio 250 ml matraz de fondo redondo. </li><li> Usando un evaporador rotatorio, retire DCM disolvente del matraz. </li><li> Seca bajo alto vacío para eliminar DCM residual. (Nota: PCL-DA debe guardarse lejos de la luz.) </li><li> Confirme acrilación con 1H NMR 22,23. </li></ol></li></ol> 2. Preparación de la SMP Andamios (Figura 1) <ol><li> Preparar la plantilla de sal fundida. <ol><li> Utilice un tamiz de 425 micras para obtener cloruro de sodio (NaCl) partículas ~ 460 ± 70 m de diámetro. (Nota: El tamaño promedio de partícula puede ser confirmado por microscopía electrónica de barrido [SEM] imágenes con el software ImageJ.) 14 </li><li> Para un vial de vidrio 3 ml (ID = 12.9 mm), añadir 1,8 g del NaCl previamente tamizada. </li><li> Se añade lentamente, en cuatro porciones, 7,5% en peso (basado en el peso de sal) de agua DI (0.146 g) al vial. Mezclar con una espátula de metal después de la adición de cada porción de agua. </li><li> Tapar el frasco, envuelva en el tejido y colocarlo verticalmente en un tubo de centrífuga. Centrifugar durante 15 min a 3220 x g. </li><li> Retire la tapa y dejar que se seque al aire O / N (~ 12 h). </li></ol></li><li> En un nuevo vial de vidrio, preparar una &quot;solución de macrómero&quot; combinando 0,15 g de PCL-DA por ml de DCM. (Nota:. Por un andamio, ~ 1 ml de solución deben estar preparados) tapa y mezcle la solución a alta velocidad en un mezclador de vórtice de ~ 1 min. </li><li> En un nuevo vial de vidrio de 3 ml, preparar una &quot;solución de fotoiniciador&quot; basado en 10% en peso de 2,2-dimetoxi-2-fenil acetofenona (DMP) en 1-vinil-2-pirrolidinona (NVP). Combine 0,115 g de DMP en 1 ml de NVP. (Nota: Por un andamio, ~ 180 l se requiere.) Cap, envolver en papel de aluminio (para bloquear la luz) y mezclar la solución a alta velocidad en un mezclador vortexpara ~ 1 min. (Nota: Si se prepara con antelación, la solución debe ser refrigerado y protegido de la luz.) </li><li> Envolver el frasco que contiene la solución de macrómero (excluyendo la tapa) con papel de aluminio (para bloquear la luz) y se añade mediante una pipeta 15 vol% (basado en el volumen total de la solución de macrómero) de la solución de fotoiniciador. Tapar y mezclar la solución a alta velocidad en un mezclador de vórtice de ~ 1 min. </li><li> Envolver el frasco que contiene la plantilla de sal fundida (excluyendo la tapa) con papel de aluminio (para bloquear la luz) y se añade mediante una pipeta la solución de macrómero / fotoiniciador preparado anteriormente (~ 0,6 ml o hasta que la plantilla está completamente cubierto). </li><li> Tapar el frasco, envuelva en el tejido y colocarlo verticalmente en un tubo de centrífuga. Centrifugar durante 10 min a 1.260 xg para distribuir la solución de macrómero en toda la plantilla. </li><li> Quite el papel de aluminio, destape el frasco y exponer a la luz UV (365 nm, 25 W) durante 3 min. O Aire seco / N. </li><li> Retire la &quot;scaffol contiene sald &quot;del vial con pinzas después de anotar y fractura de la parte superior de la ampolla de vidrio. </li><li> En un vaso de precipitados de 400 ml, ~ preparar 200 ml de una mezcla agua / disolvente de etanol (1: 1 vol: vol). </li><li> Mantener el andamio sumergido en el agua / disolvente de etanol durante 4 días con cambios de disolvente diarias. </li><li> Retire el andamio desde el disolvente y secar al aire O / N. </li></ol> 3. La aplicación de Polydopamine Revestimiento de SMP Andamios (Figura 1) <ol><li> En 400 ml vaso de precipitados equipado con una barra de agitación de teflón cubierto, preparar ~ 200 ml de una solución de clorhidrato de dopamina (2 mg / ml en 10 mM de tampón Tris, pH = 8,5, 25 ºC). Se agita a ~ 150 rpm. </li><li> Coloque una aguja desechable (longitud = 40 mm; galga = 20) en el armazón, ~ mitad de la distancia a través del andamio. Envuelva un alambre alrededor de la base de la aguja. </li><li> Sumergir el andamio (con el cubo de la aguja por encima de la superficie de la solución) en la solución de agitar la dopamina mediante el anclaje del cable para el borde del vaso de precipitados. </li><li> Desgasificar la andamio colocando una jeringa en el cubo de la aguja y su uso para extraer el aire fuera del andamio. (Nota: La desgasificación se completa cuando no más de aire se puede retiró y la solución se ha infiltrado completamente el andamio.) </li><li> Mantener el andamio sumergida en la solución de la dopamina de agitar durante 16 hr. </li><li> Retire el andamio de la solución y quitar la aguja. Enjuague con agua DI y seca en un horno de vacío a temperatura ambiente durante 24 horas. </li><li> Coloque el andamio en un horno 85 ºC durante 1 hora. </li><li> Deje que el andamio se enfríe a temperatura ambiente. El andamio cilíndrica final será ~ 6 mm de diámetro x ~ 5 mm de altura. </li></ol> 4. Evaluar el comportamiento &quot;Auto-ajuste&quot; <ol><li> Prepare un &quot;modelo irregular defecto CMF&quot; usando una hoja de plástico rígido cuyo espesor es ~ 5 mm. Use un taladro para crear un vacío dentro de la lámina de plástico con un diámetro medio ligeramente menor que ~ 6 mm, como se demuestra en la Figura 2A. </li><li> En abEAKER, agua DI de calor (que representa el uso clínico de la solución salina) a una temperatura de 60 ºC ~. </li><li> Coloque el andamio en el vaso de ~ 60 ºC agua. Utilice pinzas para empujar el andamio por debajo de la superficie del agua, la exposición de todas las áreas para el agua. Continuar por unos 2 minutos o hasta que el andamio se suavizó notablemente (Figura 2B). </li><li> Retire el andamio desde el vaso de precipitados y pulse inmediatamente (a mano) en el defecto del modelo. </li><li> Dejar enfriar a temperatura ambiente (~ 5.10 min) (Figura 2C). </li><li> Retirar del defecto para observar la nueva forma temporal, fijo y el regreso del estado relativamente más rígida (Figura 2D). </li></ol> 5. Pruebas de comportamiento con memoria de forma <ol><li> El uso de un analizador mecánico dinámico (DMA; por ejemplo, un TA Instruments Q800 como se utiliza aquí), ejecutar una prueba mecánica cíclica térmica cepa controlado por compresión en un andamio durante dos ciclos (N) para determinar la fijeza de forma (R f) ydar forma a la recuperación (R r) (Figura 3). <ol><li> Equilibrar a 60 ° C (T alta) durante 5 min. </li><li> Comprimir a una deformación máxima (m ε = 50%) a 50% / min. </li><li> Retener en ε m (5 min). </li><li> Enfriar a 25 ° C (T baja) y mantener durante 10 minutos para fijar la forma temporal. </li><li> Retire la carga. </li><li> Mida la tensión máxima en el estado libre de estrés (ε u). </li><li> Vuelva a calentar a 60 ° C (T alta) y mantener durante 10 min para recuperar la forma permanente. </li><li> Mida la cepa recuperado (ε p). </li><li> Mientras todavía estaba en 60 ° C (T alta), iniciar el ciclo de nd 2 (N = 2) mediante la compresión del andamio a 50% de la altura recuperada después del ciclo st 1 (N = 1). </li><li> Repita 5.1.3-5.1.8 Para N = 2. </li><li> Calcular R f r y R para N = 1 y 2 usando las siguientes ecuaciones: R f (N) = [ε u (N) / ε m] R r (N) = [m ε - ε p (N)] / [m ε - ε p (N -1)] </li></ol></li></ol> 6. Visualización Tamaño de poro y la interconectividad de los poros <ol><li> Usando microscopía electrónica de barrido (SEM; por ejemplo, un FEI Quanta SEM tal como se utiliza en el presente documento), observar el tamaño de poro y la interconectividad de los poros. <ol><li> Usando las pinzas para sostener el andamio SMP, sumergirse en N2 líquido durante 1 minuto. </li><li> Remover de N 2 líquido y la fractura a lo largo de la mitad del andamio con una hoja de afeitar limpia. </li><li> Con cinta de carbono, colocar una de las mitades de andamios SMP sobre la muestraen escena con la superficie fracturada hacia arriba. </li><li> Pulverización catódica abrigo con Au-Pt (~ 4 nm). </li><li> Capturar la imagen SEM a un voltaje de aceleración recomendada del 10-15 kV (Figura 4A). </li></ol></li></ol> 7. Ensayos de bioactividad in vitro <ol><li> En un tubo de centrífuga de 50 ml, añadir ~ 30 ml de 1X SBF 24. </li><li> Obtener un andamio en su forma permanente original, cilíndrica moldeado. Cortar el andamio a la mitad (a lo largo del borde circular) usando una hoja limpia. </li><li> Coloque una media andamio individuo en el tubo de centrífuga preparado y gorra. </li><li> Mantener el tubo a 37 ° C en un baño de agua en condiciones estáticas sin cambios SBF. </li><li> Después de 14 días, retire el andamio desde el SBF y aire seco durante 24 horas. </li><li> Con cinta de carbono, colocar el andamio en el escenario de la muestra con la superficie fracturada hacia arriba. </li><li> Pulverización catódica abrigo con Au-Pt (~ 4 nm). </li><li> Capturar la imagen de SEM en una reelogiado voltaje de aceleración de 10 hasta 15 kV (Figura 4B). </li></ol>

<ol>
	<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.

Este protocolo describe la preparación de un andamio a base de PCL polydopamine recubiertos cuya auto-ajuste de la conducta, así como osteoinductividad y bioactividad, hace que sea de interés en el tratamiento de defectos óseos irregulares CMF. Aspectos del protocolo pueden ser alterados para cambiar varias características de andamios. El protocolo comienza con acrilación de un PCL-diol para permitir la cura UV. En el ejemplo se informó, el ​​PCL-diol M n es de ~ 10.000...

Actualmente considerado el estándar de oro de cráneo-maxilofacial (CMF) tratamientos de defectos de hueso, el trasplante de injertos autólogos recolectados se ve obstaculizado por procedimientos de injerto complejos, morbilidad del sitio donante y la disponibilidad limitada de 1. Una dificultad particular se perfila y se fija el autoinjerto rígida firmemente en el defecto a fin de obtener la oseointegración y para evitar la reabsorción del injerto. La ingeniería de tejidos se ha investigado como una estrategia alternativa al autoinjerto y sustitutos óseos sintéticos (por ejemplo, cemento óseo) 2,3. Fundamental para el éxito de un enfoque de la ingeniería de tejidos es un andamiaje con un conjunto específico de propiedades. En primer lugar, a fin de lograr la osteointegración, el andamio debe formar un estrecho contacto con el tejido óseo adyacente 4. El andamio también debe ser osteoconductiva, permitiendo la migración celular, difusión de nutrientes y 4,5 deposición neotejido. Este comportamiento se consigue generalmente con sca biodegradablesffolds exhiben una morfología de poro altamente interconectado. Por último, el andamio debe ser bioactivo con el fin de promover la integración y la unión con el tejido óseo circundante 5. A continuación, presentamos un protocolo para preparar un andamio ingeniería de tejidos con estas propiedades. Es importante destacar que este andamio exhibe la capacidad de &quot;auto-ajuste&quot; en defectos irregulares CMF debido a su comportamiento de memoria de forma 6. Polímeros con memoria de forma termosensible (SMPS) se sabe que someterse a cambio de forma cuando se expone al calor 7,8. SMP se componen de &quot;NETPoints&quot; (es decir, químicas o reticulaciones físicas) que determinan la forma permanente y &quot;segmentos de conexión&quot; que mantienen la forma temporal y recuperan la forma permanente. Los segmentos de conmutación presentan una temperatura de transición térmica (T trans) que corresponde a cualquiera de la transición vítrea (Tg) o se funden de transición (Tm) del polímero. ComoEn consecuencia, las SMP puede ser secuencial deforma en una forma temporal en T&gt; T trans, fijo en forma temporal en T &lt;T trans, y se recuperó a la forma permanente en T&gt; T trans. Así, un andamio de SMP podría lograr &quot;auto-ajuste&quot; dentro de un defecto recurrente de la siguiente 6. Después de la exposición al calor de solución salina (T&gt; T trans), un andamio de SMP se convertiría maleable, permitiendo un andamio cilíndrica genéricamente preparado para estar en un defecto irregular presionado a mano, con la recuperación de la forma promover la expansión del andamio hasta el límite del defecto. Después de la refrigeración (T &lt;T trans), el andamio volvería a su estado relativamente más rígida, con forma de fijeza mantener su nueva forma temporal dentro del defecto. En este protocolo, un andamio SMP se prepara a partir de policaprolactona (PCL), un polímero biodegradable estudió extensivamente para la regeneración de tejidos y otras aplicaciones biomédicas 9-11. Para memoria de forma, THe T m de PCL sirve como el T trans y varía entre 43 y 60 ºC, dependiendo del peso molecular de la PCL 12. En este protocolo, el T trans (es decir Tm) del andamio es 56,6 ± 0,3 ºC 6. A fin de lograr osteoconductividad, se desarrolló un protocolo para hacer andamios SMP basados ​​en PCL con poros interconectados altamente basa en un método de fundición a presión de partículas de disolvente-lixiviación (SCPL) 6,13,14. Diacrilato de policaprolactona (PCL-DA) (M n = ~ 10.000 g / mol) se utilizó para permitir el rápido, la reticulación fotoquímica y se disolvió en diclorometano (DCM) para permitir disolvente a presión sobre la plantilla sal. Después de cura fotoquímica y evaporación del disolvente, la plantilla sal se separó por lixiviación en agua. El tamaño medio de la sal regula el tamaño de los poros del andamio. Es importante destacar que la plantilla de la sal se fusionó con agua antes de disolvente de fundición a presión para lograr interconnectivi de porodad. La bioactividad se imparte al andamio SMP por la formación in situ de un recubrimiento polydopamine en paredes de los poros 6. La bioactividad es a menudo introducido en andamios por la inclusión de vidrio o de cerámica de vidrio rellenos 15. Sin embargo, estos pueden dar lugar a propiedades mecánicas frágiles no deseados. La dopamina se ha demostrado para formar una capa adherente polydopamine, delgada sobre una variedad de sustratos 16-19. En este protocolo, el andamio SMP se sometió a una solución ligeramente básica (pH = 8.5) de la dopamina para formar un recubrimiento de nanothick polydopamine en todas las superficies de pared de poro 6. Además de mejorar la hidrofilia de la superficie para mejorar la adhesión celular y la propagación, polydopamine ha demostrado ser bioactivo en términos de formación de hidroxiapatita (HAp) tras la exposición a fluido corporal simulado (SBF) 18,20,21. En un último paso, el andamiaje recubierto se expone a un tratamiento térmico a 85 ºC (T&gt; T trans) which conduce al andamio densificación. El tratamiento térmico se señaló anteriormente a ser esencial para el comportamiento de memoria de forma de andamio, tal vez debido a dominios cristalinos PCL reorganizar a mayor proximidad 14. Tenemos, además, describen los métodos para caracterizar el comportamiento de auto-ajuste dentro de un defecto modelo irregular, moldear el comportamiento de memoria en términos ensayos de compresión mecánica cíclica térmicos de deformación controlada (es decir, recuperación de la forma y la forma de fijeza), poro morfología, y en la bioactividad in vitro. También se presentan estrategias para adaptar las propiedades de andamios.

<table border="0" cellpadding="0" cellspacing="0">
	<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.

El andamio SMP basados ​​en PCL resultante es capaz de auto-ajuste en un modelo CMF defecto (Figura 2). Después de una breve exposición a calentar solución salina (~ 60 ° C), el andamio cilíndrica suaviza permitiendo que el andamio para ser presionado manualmente en y expandir dentro del defecto modelo. Después de enfriar a RT, el andamio se fija en su nueva forma temporal que se retiene después de la retirada del defecto. El comportamiento de memoria de forma de ...

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 &quot;Self-fitting&quot; 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.

La fabricación de una memoria de forma &quot;Auto-ajuste&quot; basado en PCL Bioactivos, Polymer Andamios

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

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

12.5K vistas.  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.

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

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.

Los polímeros con memoria de forma para el cultivo celular activo

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 ...

Investigación

Bioingeniería

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, 'SurgiLux': Preparation and Demonstration

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures can act as a nidus for infection and in many procedures are unable to effect wound repair or interfere with functional tissue regeneration.1 Surgical glues and adhesives, such as those based on fibrin and cyanoacrylates, have been developed as alternatives to sutures for the repair of such wounds. However, current commercial adhesives also have significant disadvantages, ranging from viral and prion transfer and a lack of repair strength as with the fibrin glues, to tissue toxicity and a lack of biocompatibility for the cyanoacrylate based adhesives. Furthermore, currently available surgical adhesives tend to be gel-based and can have extended curing times which limit their application.2 Similarly, the use of UV lasers to facilitate cross-linking mechanisms in protein-based or albumin 'solders' can lead to DNA damage while laser tissue welding (LTW) predisposes thermal damage to tissues.3 Despite their disadvantages, adhesives and LTW have captured approximately 30% of the wound closure market reported to be in excess of US $5 billion per annum, a significant testament to the need for sutureless technology.4
In the pursuit of sutureless technology we have utilized chitosan as a biomaterial for the development of a flexible, thin film, laser-activated surgical adhesive termed 'SurgiLux'. This novel bioadhesive uses a unique combination of biomaterials and photonics that are FDA approved and successfully used in a variety of biomedical applications and products. SurgiLux overcomes all the disadvantages associated with sutures and current surgical adhesives (see Table 1).
In this presentation we report the relatively simple protocol for the fabrication of SurgiLux and demonstrate its laser activation and tissue weld strength. SurgiLux films adhere to collagenous tissue without chemical modification such as cross-linking and through irradiation using a comparatively low-powered (120 mW) infrared laser instead of UV light. Chitosan films have a natural but weak adhesive attraction to collagen (~3 KPa), laser activation of the chitosan based SurgiLux films emphasizes the strength of this adhesion through polymer chain interactions as a consequence of transient thermal expansion.5 Without this 'activation' process, SurgiLux films are readily removed.6-9 SurgiLux has been tested both in vitro and in vivo on a variety of tissues including nerve, intestine, dura mater and cornea. In all cases it demonstrated good biocompatibility and negligible thermal damage as a consequence of irradiation.6-10

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, &#039;SurgiLux&#039;: Preparation and Demonstration

The fabrication of a novel, flexible thin film surgical adhesive from FDA approved ingredients, chitosan and indocyanine green is described. Bonding of this adhesive to collagenous tissue through a simple activation process with a low-powered infra-red laser is demonstrated.

A Based Chitosan, Laser adhesivo activado Thin Film quirúrgica, &#39;SURGILUX&#39; Preparación y Demostración

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures ...

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. 
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

A method is discussed by which the in vivo mechanical behavior of stimuli-responsive materials is monitored as a function of time. Samples are tested ex vivo using a microtensile tester with environmental controls to simulate the physiological environment. This work further promotes understanding the in vivo behavior of our material.

Prueba Microtracción ambientalmente controlado mecánicamente de adaptación nanocompuestos poliméricos para<em&gt; Ex vivo</em&gt; Caracterización

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

A &#8220;sheath&#8221; fluid passing through a microfluidic channel at low Reynolds number can be directed around another &#8220;core&#8221; stream and used to dictate the shape as well as the diameter of a core stream.&#160;Grooves in the top and bottom of a microfluidic channel were designed to direct the sheath fluid and shape the core fluid.&#160;By matching the viscosity and hydrophilicity of the sheath and core fluids, the interfacial effects are minimized and complex fluid shapes can be formed.&#160;Controlling the relative flow rates of the sheath and core fluids determines the cross-sectional area of the core fluid.&#160;Fibers have been produced with sizes ranging from 300 nm to ~1 mm, and fiber cross-sections can be round, flat, square, or complex as in the case with double anchor fibers. Polymerization of the core fluid downstream from the shaping region solidifies the fibers.&#160;Photoinitiated click chemistries are well suited for rapid polymerization of the core fluid by irradiation with ultraviolet light.&#160;Fibers with a wide variety of shapes have been produced from a list of polymers including liquid crystals, poly(methylmethacrylate), thiol-ene and thiol-yne resins, polyethylene glycol, and hydrogel derivatives. Minimal shear during the shaping process and mild polymerization conditions also makes the fabrication process well suited for encapsulation of cells and other biological components.

Two adjacent fluids passing through a grooved microfluidic channel can be directed to form a sheath around a prepolymer core; thereby&#160;determining both shape and cross-section. Photoinitiated polymerization, such as thiol click chemistry, is well suited for rapidly solidifying the core fluid into a microfiber with predetermined size and shape.

Fabricación Microfluídica De Fibras Poliméricas Y Biohíbridas Con Tamaño y Forma Prediseñados

A &#8220;sheath&#8221; fluid passing through a microfluidic channel at low Reynolds number can be directed around another &#8220;core&#8221; stream and ...

Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose and short sisal fibers are dispersed into a water suspension containing bacterial cellulose. The fiber and nanocellulose suspension is then filtered (using vacuum or gravity) and the wet filter cake pressed to squeeze out any excess water, followed by a drying step. This will result in the hornification of the bacterial cellulose network, holding the loose natural fibers together.
Our method is specially suited for the manufacturing of rigid and robust preforms of hydrophilic fibers. The porous and hydrophilic nature of such fibers results in significant water uptake, drawing in the bacterial cellulose dispersed in the suspension. The bacterial cellulose will then be filtered against the surface of these fibers, forming a bacterial cellulose coating. When the loose fiber-bacterial cellulose suspension is filtered and dried, the adjacent bacterial cellulose forms a network and hornified to hold the otherwise loose fibers together.
The introduction of bacterial cellulose into the preform resulted in a significant increase of the mechanical properties of the fiber preforms. This can be attributed to the high stiffness and strength of the bacterial cellulose network. With this preform, renewable high performance hierarchical composites can also be manufactured by using conventional composite production methods, such as resin film infusion (RFI) or resin transfer molding (RTM). Here, we also describe the manufacturing of renewable hierarchical composites using double bag vacuum assisted resin infusion.

We present a novel method of manufacturing rigid and robust short natural fiber preforms using a papermaking process. Bacterial cellulose acts simultaneously as the binder for the loose fibers and provides rigidity to the fiber preforms. These preforms can be infused with a resin to produce truly green hierarchical composites.

Fabricación De robustos Fibra Natural Preformas Utilizando bacteriana celulosa como Carpeta

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose ...

Fabrication of Mechanically Tunable and Bioactive Metal Scaffolds for Biomedical Applications

Biometal systems have been widely used for biomedical applications, in particular, as load-bearing materials. However, major challenges are high stiffness and low bioactivity of metals. In this study, we have developed a new method towards fabricating a new type of bioactive and mechanically reliable porous metal scaffolds-densified porous Ti scaffolds. The method consists of two fabrication processes, 1) the fabrication of porous Ti scaffolds by dynamic freeze casting, and 2) coating and densification of the porous scaffolds. The dynamic freeze casting method to fabricate porous Ti scaffolds allowed the densification of porous scaffolds by minimizing the chemical contamination and structural defects. The densification process is distinctive for three reasons. First, the densification process is simple, because it requires a control of only one parameter (degree of densification). Second, it is effective, as it achieves mechanical enhancement and sustainable release of biomolecules from porous scaffolds. Third, it has broad applications, as it is also applicable to the fabrication of functionally graded porous scaffolds by spatially varied strain during densification.

Bioactive and mechanically reliable metal scaffolds have been fabricated through a method which consists of two processes, dynamic freeze casting for the fabrication of porous Ti, and coating and densification of the Ti scaffolds. The densification process is simple, effective and applicable to the fabrication of functionally graded scaffolds.

Fabricación de Mecánicamente sintonizable y Bioactivos metal andamios para Aplicaciones Biomédicas

Biometal systems have been widely used for biomedical applications, in particular, as load-bearing materials. However, major challenges are high stiffness ...

Fabrication of Inverted Colloidal Crystal Poly(ethylene glycol) Scaffold: A Three-dimensional Cell Culture Platform for Liver Tissue Engineering

The ability to maintain hepatocyte function in vitro, for the purpose of testing xenobiotics&#39; cytotoxicity, studying virus infection and developing drugs targeted at the liver, requires a platform in which cells receive proper biochemical and mechanical cues. Recent liver tissue engineering systems have employed three-dimensional (3D) scaffolds composed of synthetic or natural hydrogels, given their high water retention and their ability to provide the mechanical stimuli needed by the cells. There has been growing interest in the inverted colloidal crystal (ICC) scaffold, a recent development, which allows high spatial organization, homotypic and heterotypic cell interaction, as well as cell-extracellular matrix (ECM) interaction. Herein, we describe a protocol to fabricate the ICC scaffold using poly (ethylene glycol) diacrylate (PEGDA) and the particle leaching method. Briefly, a lattice is made from microsphere particles, after which a pre-polymer solution is added, properly polymerized, and the particles are then removed, or leached, using an organic solvent (e.g., tetrahydrofuran). The dissolution of the lattice results in a highly porous scaffold with controlled pore sizes and interconnectivities that allow media to reach cells more easily. This unique structure allows high surface area for the cells to adhere to as well as easy communication between pores, and the ability to coat the PEGDA ICC scaffold with proteins also shows a marked effect on cell performance. We analyze the morphology of the scaffold as well as the hepatocarcinoma cell (Huh-7.5) behavior in terms of viability and function to explore the effect of ICC structure and ECM coatings. Overall, this paper provides a detailed protocol of an emerging scaffold that has wide applications in tissue engineering, especially liver tissue engineering.

Fabrication of Inverted Colloidal Crystal Polyethylene glycol Scaffold: A Three-dimensional Cell Culture Platform for Liver Tissue Engineering

This manuscript presents a detailed protocol for the fabrication of an emerging three-dimensional hepatocyte culture platform, the inverted colloidal crystal scaffold, and the concomitant techniques to assess hepatocyte behavior. The size-controllable pores, interconnectivity and ability to conjugate extracellular matrix proteins to the poly(ethylene glycol) (PEG) scaffold enhance Huh-7.5 cell performance.

La fabricación de cristal invertida coloidal poli (etilenglicol) Andamios: Una célula Plataforma de cultivo tridimensional para ingeniería de tejidos de hígado

The ability to maintain hepatocyte function in vitro, for the purpose of testing xenobiotics&#39; cytotoxicity, studying virus infection and developing ...

Fabrication and Characterization of Optical Tissue Phantoms Containing Macrostructure

The rapid development of new optical imaging techniques is dependent on the availability of low-cost, customizable, and easily reproducible standards. By replicating the imaging environment, costly animal experiments to validate a technique may be circumvented. Predicting and optimizing the performance of in vivo and ex vivo imaging techniques requires testing on samples that are optically similar to tissues of interest. Tissue-mimicking optical phantoms provide a standard for evaluation, characterization, or calibration of an optical system. Homogenous polymer optical tissue phantoms are widely used to mimic the optical properties of a specific tissue type within a narrow spectral range. Layered tissues, such as the epidermis and dermis, can be mimicked by simply stacking these homogenous slab phantoms. However, many in vivo imaging techniques are applied to more spatially complex tissue where three dimensional structures, such as blood vessels, airways, or tissue defects, can affect the performance of the imaging system. 
This protocol describes the fabrication of a tissue-mimicking phantom that incorporates three-dimensional structural complexity using material with optical properties of tissue. Look-up tables provide India ink and titanium dioxide recipes for optical absorption and scattering targets. Methods to characterize and tune the material optical properties are described. The phantom fabrication detailed in this article has an internal branching mock airway void; however, the technique can be broadly applied to other tissue or organ structures.

Optical tissue phantoms are essential tools for calibration and characterization of optical imaging systems and validation of theoretical models. This article details a method for phantom fabrication that includes replication of tissue optical properties and three-dimensional tissue structure.

Fabricación y caracterización de tejido óptico fantasmas que contiene macroestructura

The rapid development of new optical imaging techniques is dependent on the availability of low-cost, customizable, and easily reproducible standards. By ...

Microdissection of Primary Renal Tissue Segments and Incorporation with Novel Scaffold-free Construct Technology

Kidney transplantation is now a mainstream therapy for end-stage renal disease. However, with approximately 96,000 people on the waiting list and only one-fourth of these patients achieving transplantation, there is a dire need for alternatives for those with failing organs. In order to decrease the harmful consequences of dialysis along with the overall healthcare costs it incurs, active investigation is ongoing in search of alternative solutions to organ transplantation. Implantable tissue-engineered renal cellular constructs are one such feasible approach to replacing lost renal functionality. Here, described for the first time, is the microdissection of murine kidneys for isolation of living corticomedullary renal segments. These segments are capable of rapid incorporation within scaffold-free endothelial-fibroblast constructs which may enable rapid connection with host vasculature once implanted. Adult mouse kidneys were procured from living donors, followed by stereoscope microdissection to obtain renal segments 200 - 300 &#181;m in diameter. Multiple renal constructs were fabricated using primary renal segments harvested from only one kidney. This method demonstrates a procedure which could salvage functional renal tissue from organs that would otherwise be discarded.

Tissue-engineered renal constructs provide a solution for the organ shortage and deleterious effects of dialysis. Here, we describe a protocol to micro dissect murine kidneys for isolation of cortico-medullary segments. These segments are implanted into scaffold-free cellular constructs, forming renal organoids.

Microdisección de segmentos de tejido Renal primaria y la incorporación con la tecnología de construcción de andamio-libre nuevo

Kidney transplantation is now a mainstream therapy for end-stage renal disease. However, with approximately 96,000 people on the waiting list and only ...

Scalable Fabrication of Stretchable, Dual Channel, Microfluidic Organ Chips

A significant number of lead compounds fail in the pharmaceutical pipeline because animal studies often fail to predict clinical responses in human patients. Human Organ-on-a-Chip (Organ Chip) microfluidic cell culture devices, which provide an experimental in vitro platform to assess efficacy, toxicity, and pharmacokinetic (PK) profiles in humans, may be better predictors of therapeutic efficacy and safety in the clinic compared to animal studies. These devices may be used to model the function of virtually any organ type and can be fluidically linked through common endothelium-lined microchannels to perform in vitro studies on human organ-level and whole body-level physiology without having to conduct experiments on people. These Organ Chips consist of two perfused microfluidic channels separated by a permeable elastomeric membrane with organ-specific parenchymal cells on one side and microvascular endothelium on the other, which can be cyclically stretched to provide organ-specific mechanical cues (e.g., breathing motions in lung). This protocol details the fabrication of flexible, dual channel, Organ Chips through casting of parts using 3D printed molds, enabling combination of multiple casting and post-processing steps. Porous poly (dimethyl siloxane) (PDMS) membranes are cast with micrometer sized through-holes using silicon pillar arrays under compression. Fabrication and assembly of Organ Chips involves equipment and steps that can be implemented outside of a traditional cleanroom. This protocol provides researchers with access to Organ Chip technology for in vitro organ- and body-level studies in drug discovery, safety and efficacy testing, as well as mechanistic studies of fundamental biological processes.

Here, we present a protocol that describes the fabrication of stretchable, dual channel, organ chip microfluidic cell culture devices for recapitulating organ-level functionality in vitro.

Fabricación escalable de elástico, doble canal, Chips microfluídicos órgano

A significant number of lead compounds fail in the pharmaceutical pipeline because animal studies often fail to predict clinical responses in human ...