This work was financially supported by INSTM.

1.脚手架制造<ol><li>磨的NaCl在实验室混合器20分钟，并使其干燥在100℃的加热器。 </li><li>把干燥的NaCl（在时间45克）的筛分机30分钟，在可用的最高频率而不在共振发生。采集6盐组分，从500微米到1000微米（M 500）;从300微米至500微米（M 300）;从100到200微米（M 100）;从90微米至100（M 90）;从盐颗粒45微米至65微米（M 45）和最后M 10的大小小于45微米， 如图1图式。 </li><li>真空干燥一夜所有材料，以避免处理过程中发生水解断裂。在聚合物的情况下 - - 玻璃化转变每种材料中，为了最大限度地发挥干燥程度不克服选择温度。因此，选择T = 90℃，PLA和T = 25℃，PEG，T = 105℃的NaCl。 </li><li>饲料PLA，PEG和氯化钠，分别为20/5/75重量百分比的组合物，以在T = 190℃的间歇混合机的操作和n = 60转，然后对经过处理它们，直到实现转矩的恒定值，通常10分钟。此后，迅速地收集得到的物质。 </li><li>通过使用实验室压机在210℃下操作制备的单层，放在适当的圆柱形模子的共混物用直径为10毫米，3毫米的高度并保持在环境压力60秒，并在180巴3分钟。此后，冷却该混合物在室温下，保持180巴的压力。 </li><li>通过压缩成型的三层组件<ol><li>在相同的方式，在（1.5）中所述，但使用不同的模具，即具有直径为10毫米和1毫米的高度准备每个单层。最后，得到具有直径为10毫米，1毫米的高度6磁盘，包含六个不同的颗粒尺寸:M 500，M 300，M 100， </li><li>佛ř组装三层支架A（TLS A）堆放m个500，M 300和M 100中的圆筒形模具的内部并在实验室压机压缩模铸它们在210℃在环境压力为60秒和3分钟以上180条，然后在室温冷却，保持180巴的压力。 注:通过按照相同的程序作为用于TLS A.通过堆叠在每个其它M 90中，M 45和M 10在相同的模具中并进行压缩 - 模制操作准备TSL乙</li></ol></li><li>从圆柱形模具中取出光盘，并把它们在沸腾软化水洗澡，不搅拌。 3小时后，从浴中取出所得的多孔结构，并让他们干，在室温下在化学罩12小时。 </li></ol> 2，形态分析<ol><li>通过扫描电子显微镜评价的支架的形态。 <ol><li>打破样品液氮中，然后装上在铝存根样品使用粘合碳胶带。最后，溅射coate金用于成像之前氩气气氛下90秒，以避免在试验过程中的静电放电。 </li></ol></li></ol> 3.脚手架孔径<ol><li>阐述通过SEM分析用图像处理软件能够识别该支架的孔尺寸分布获得的图像。 注意:在本工作的细孔径分布进行了分析使用基于MATLAB软件先前所述33 </li></ol> 4.孔隙度<ol><li>浸出之前称重所述样品和评价根据以下表达式的理论孔隙率: <img alt="式（1）" src="/files/ftp_upload/54595/54595eq1.jpg" /> 注:M 氯化钠 ， 男PEG和m PLA，分别是氯化钠，PEG和PLA的理论质量，假定均匀的共混物。 ŧ他密度的NaCl，PEG和PLA的（ρ）分别为2.16克/厘米3，1.12克/厘米3ë1.24克/厘米3。 </li><li>称量样品淋洗并以评估样品（ρ 支架 ）的表观密度干燥后，然后评估实孔隙率支架的表观密度以及由非多孔聚乳酸的密度之间的比率的倒数使用表达式（2）。 注:表达了支架的空体积和全部体积的支架（空+满）之间的比率。 <img alt="公式（2）" src="/files/ftp_upload/54595/54595eq2.jpg" /></li></ol> 5.机械性能<ol><li>测试使用拉伸机，搭载了1千牛顿负荷细胞下的压缩模式的样品。设置为1毫米分钟-1的恒定应变速率。 </li><li>为了研究在生理环境中的样品的机械性能，装备dynamometeR，其中，在37℃含有浴（PBS）（pH值= 7.4）中，用相同的设置，在点5.1中所述进行测试。 <ol><li>在潮湿环境中的每个测量之前，浸泡在用PBS样品在真空烧瓶5分钟，以让PBS填充所有的孔。此后，允许支架在37℃下留在PBS 15分钟以到达设定点温度。 </li></ol></li><li>通过使用自定义设计的界面强度测试设备，连接到力学试验机按照文献32,34描述的方法确定TL A和TL B的层之间的界面粘结强度（IAS）。 <ol><li>固定在钻机的支架，并确保其与机器的称重传感器和基地台板正确对准。通过使用高粘度的胶粘剂连接支架样品铝测试存根，并将它们放到设备进行测试。 </li><li>对于潮湿条件下的测试，滋润在PBS样品1小时PRI或测试。使用1千牛顿载荷传感器，以1mm分钟-1的应变速率施加的拉伸负荷下。 注意:考虑到可能发生故障或者在层中的一个的极限拉伸强度，或因为在界面剥离的。评价在IAS为应力 - 应变曲线的最大强度。 </li></ol></li></ol>

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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Graphene+Nanoplatelets+on+the+Physical+and+Antimicrobial+Properties+of+Biopolymer-Based+Nanocomposites.">Effect of Graphene Nanoplatelets on the Physical and Antimicrobial Properties of Biopolymer-Based Nanocomposites.</a> Materials. 9 (5), 351 (2016).</li><li>Maio, A., Fucarino, R., Khatibi, R., Rosselli, S., Bruno, M., Scaffaro, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+approach+to+prevent+graphene+oxide+re-aggregation+during+the+melt+compounding+with+polymers.">A novel approach to prevent graphene oxide re-aggregation during the melt compounding with polymers.</a> Composites Science and Technology. 119, 131-137 (2015).</li><li>Maio, A., Agnello, 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=A+rapid+and+eco-friendly+route+to+synthesize+graphene-doped+silica+nanohybrids.">A rapid and eco-friendly route to synthesize graphene-doped silica nanohybrids.</a> Journal of Alloys and Compounds. 664, 428-438 (2015).</li><li>Maio, A., Giallombardo, D., Scaffaro, R., Piccionello, A. P., Pibiri, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+a+fluorinated+graphene+oxide-silica+nanohybrid:+improving+oxygen+affinity.">Synthesis of a fluorinated graphene oxide-silica nanohybrid: improving oxygen affinity.</a> RSC Advances. 6 (52), 46037-46047 (2016).</li></ol>

The authors declare that they have no competing financial interests.

第一个关键步骤是筛分效率的最优化。 NaCl的粒径的高控制为具有期望的孔径分布制备支架的基础。另一个关键步骤是避免从模具样品提取期间薄PLA单层的断裂。图像处理分析可能不能代表整个装置。 期间拉伸试验中，样品可撕远离设备。 向筛分步骤之前，确定该盐已在为了得到NaCl粒子大小的一个更高的控制得到了很好的干燥。这个问题很重要，特别是...

The interest in biodegradable polymers has grown in importance during the last years both in academia and in the industry, due to the rising concerns regarding plastic waste and the reduction in using non-renewable sources1-7. In particular, biocompatible and biodegradable synthetic polymers are widespread in several biomedical application fields, such as drug controlled release8,9, absorbable suture threads8,10, bioprocess intensification11 and tissue engineering12.
Tissue engineering focuses on the development of devices capable to restore and maintain normal function in diseased or injured tissues. Most of the native tissues are composed by different types of cells and extracellular matrices (ECMs) in specific spatial hierarchies. For example, articular cartilage (AC) consists of different zones with varying types and orientations of collagen fibers and collagen-binding proteins. Moreover, cartilage and bone show significantly different hierarchical structures. In this context, the preparation of multilayer scaffolds with engineered properties in each layer could allow replacing heterogeneous tissues by taking into accounts all the local microenvironments of these complex systems13,14.
Based on the cellular/biological and/or physical-chemical characteristics of the scaffolds, the main strategies adopted by the tissue engineering can be divided into monophasic, biphasic, and triphasic. Biphasic and triphasic approaches (BTA) use two or three different pores architectures, materials, or fillers to prepare multilayered functional devices. Furthermore, a single material can be used to achieve biphasic or triphasic devices, as long as it is possible to create a gradient in its physical properties12.
Cell migration plays a key-role in the morphogenesis, inflammation, wound healing and tumor metastasis. Cell movement is encouraged by the presence of a gradient of chemical-physical properties from the surface to the core of the device. Therefore, biomaterials fulfilling the above discussed requirements can be helpful in studying cell migration. In addition to chemical gradients that trigger cells migration (chemotaxis), mechanical properties of cells culture substrate can also lead to cell movement (mechanotaxis)15.
The multilayer structure can also provide the tunable release of specific drugs incorporated within the polymer matrix, by changing the specific area of the layer or the amount of loaded drugs. 
Over the past decade, in order to develop scaffolds possessing a discrete or continuous gradient of morphological properties, such as porosity or pore size, several approaches have been presented16-31. The most recent papers focused on the preparation of BTA by adopting: particle leaching 12,28,32, gas foaming technique16, electrospinning17-19, layer by layer casting technique20, rapid prototyping21,22, thermally induced phase separation (TIPS)22, centrifugation freeze drying24,25, triply periodic minimal surfaces (TPMS)26, freeze casting27-30.
Within the frame of this work, we present a fast and simple route to achieve PLA-based three-layer porous scaffolds (TLS), by combining melt mixing, compression molding and salt leaching. Differently from most of the technologies commonly used for scaffold production, the strategy herein adopted can be considered fully eco-friendly, since it does not require any toxic solvent potentially dangerous for environment and for living cells and tissues32. The basic processing-structure-property relationships established in this study by analyzing both morphological features and mechanical behavior of fabricated devices provide guidance to future advances in designing multifunctional graded scaffolds with specific target properties.

<table><tbody><tr><td>Poly(lactic acid)</td><td>NatureWorks</td><td>PLA 2002D</td><td></td></tr><tr><td>Poly(ethylene glycol)</td><td>Sigma</td><td>83797-1KG-F</td><td></td></tr><tr><td>Sodium Cloride</td><td>Sigma</td><td>793566-5KG-D</td><td></td></tr><tr><td>Phosfate Buffer Solution</td><td>Sigma</td><td>P5368-10PAK</td><td></td></tr><tr><td>Laboratory Mixer</td><td>Brabender</td><td>PLE 330 - Plasticorder</td><td></td></tr><tr><td>Laboratory Press</td><td>Carver</td><td></td><td></td></tr><tr><td>Scanning Electron Microscopy</td><td>Phenom-world</td><td>ProX</td><td></td></tr><tr><td>Universal Testing Machine</td><td>Instron</td><td>3365 (UK)</td><td></td></tr><tr><td>BioPuls Bath</td><td>Instron, Norwood</td><td></td><td></td></tr><tr><td>Sieving Machine</td><td>Endecotts</td><td>E.V.F.1.</td><td></td></tr><tr><td>Vacuum Oven</td><td>ISCO</td><td>NSV9035</td><td></td></tr><tr><td>Precision Balance</td><td>Sartorius</td><td>AX224</td><td></td></tr></tbody></table>

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.

NaCl粒子大小对支架的孔结构的影响被调查样品的形貌和分别计算由图像分析孔径分布，定性和定量评估图2a - F示出了所得的单层支架的SEM显微照片从含有不同氯化钠颗粒尺寸材料盐析。 更详细地，男500（ 图2a）显示孔为500微米的平均直径，这可能是由于盐的颗粒直径在熔融混合期间高于...

Watch this Scientific Journal Video about A Facile and Eco-friendly Route to Fabricate PolyLactic Acid Scaffolds with Graded Pore Size at JoVE.com

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 ...

a-facile-eco-friendly-route-to-fabricate-poly-lactic-acid-scaffolds

Research

JoVE Journal

Bioengineering

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

8.6K 次观看.  University of Palermo. 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.

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

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

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 ...

Multi-Scale Modification of Metallic Implants With Pore Gradients, Polyelectrolytes and Their Indirect Monitoring In vivo

Metallic implants, especially titanium implants, are widely used in clinical applications. Tissue in-growth and integration to these implants in the tissues are important parameters for successful clinical outcomes. In order to improve tissue integration, porous metallic implants have being developed. Open porosity of metallic foams is very advantageous, since the pore areas can be functionalized without compromising the mechanical properties of the whole structure. Here we describe such modifications using porous titanium implants based on titanium microbeads. By using inherent physical properties such as hydrophobicity of titanium, it is possible to obtain hydrophobic pore gradients within microbead based metallic implants and at the same time to have a basement membrane mimic based on hydrophilic, natural polymers. 3D pore gradients are formed by synthetic polymers such as Poly-L-lactic acid (PLLA) by freeze-extraction method. 2D nanofibrillar surfaces are formed by using collagen/alginate followed by a crosslinking step with a natural crosslinker (genipin). This nanofibrillar film was built up by layer by layer (LbL) deposition method of the two oppositely charged molecules, collagen and alginate. Finally, an implant where different areas can accommodate different cell types, as this is necessary for many multicellular tissues, can be obtained. By, this way cellular movement in different directions by different cell types can be controlled. Such a system is described for the specific case of trachea regeneration, but it can be modified for other target organs. Analysis of cell migration and the possible methods for creating different pore gradients are elaborated. The next step in the analysis of such implants is their characterization after implantation. However, histological analysis of metallic implants is a long and cumbersome process, thus for monitoring host reaction to metallic implants in vivo an alternative method based on monitoring CGA and different blood proteins is also described. These methods can be used for developing in vitro custom-made migration and colonization tests and also be used for analysis of functionalized metallic implants in vivo without histology.

Multi-Scale Modification of Metallic Implants With Pore Gradients, Polyelectrolytes and Their Indirect Monitoring In vivo

In this video, we will demonstrate modification techniques for porous metallic implants to improve their functionality and to control cell migration. Techniques include development of pore gradients to control cell movement in 3D and production of basement membrane mimics to control cell movement in 2-D. Also, a HPLC-based method for monitoring implant integration in-vivo via analysis of blood proteins is described.

多尺度孔梯度，聚电解质和间接监测改性金属植入物<em&gt;在体内</em

Metallic implants, especially titanium implants, are widely used in  clinical applications. Tissue in-growth and integration to these implants in  the ...

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.

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 ...

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 ...

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.

加工机械可调和生物活性金属支架的生物医学应用

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.

倒胶体晶体聚（乙二醇）脚手架制作:肝脏组织工程三维细胞培养平台

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

3D Printed Porous Cellulose Nanocomposite Hydrogel Scaffolds

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with controlled pore structure and mechanical properties. Cellulose nanocrystals (CNCs, 69.62 wt%) based hydrogel ink with matrix (sodium alginate and gelatin) was developed and 3D printed into scaffolds with uniform and gradient pore structure (110-1,100 &#181;m). The scaffolds showed compression modulus in the range of 0.20-0.45 MPa when tested in simulated in vivo conditions (in distilled water at 37 &#176;C). The pore sizes and the compression modulus of the 3D scaffolds matched with the requirements needed for cartilage regeneration applications. This work demonstrates that the consistency of the ink can be controlled by the concentration of the precursors and porosity can be controlled by the 3D printing process and both of these factors in return defines the mechanical properties of the 3D printed porous hydrogel scaffold. This process method can therefore be used to fabricate structurally and compositionally customized scaffolds according to the specific needs of patients.&#160;

The three critical steps of this protocol are i) developing the right composition and consistency of the cellulose hydrogel ink, ii) 3D printing of scaffolds into various pore structures with good shape fidelity and dimensions and iii) demonstration of the mechanical properties in simulated body conditions for cartilage regeneration.

三维印刷多孔纤维素纳米复合水凝胶脚手架

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with ...

Core/shell Printing Scaffolds For Tissue Engineering Of Tubular Structures

Three-dimensional (3D) printing of core/shell filaments allows direct fabrication of channel structures with a stable shell that is cross-linked at the interface with a liquid core. The latter is removed post-printing, leaving behind a hollow tube. Integrating an additive manufacturing technique (like the one described here with tailor-made [bio]inks, which structurally and biochemically mimic the native extracellular matrix [ECM]) is an important step towards advanced tissue engineering. However, precise fabrication of well-defined structures requires tailored fabrication strategies optimized for the material in use. Therefore, it is sensible to begin with a set-up that is customizable, simple-to-use, and compatible with a broad spectrum of materials and applications. This work presents an easy-to-manufacture core/shell nozzle with luer-compatibility to explore core/shell printing of woodpile structures, tested with a well-defined, alginate-based scaffold material formulation.

Presented here is a simple-to-use, core/shell, three-dimensional bioprinting set-up for one-step fabrication of hollow scaffolds, suitable for tissue engineering of vascular and other tubular structures.

管状结构组织工程的核心/壳印刷支架

Three-dimensional (3D) printing of core/shell filaments allows direct fabrication of channel structures with a stable shell that is cross-linked at the ...

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.