Electrospun polylactide/silk fibroin–gelatin composite tubular scaffolds for small‐diameter tissue engineering blood vessels

Many synthetic scaffolds have been used as vascular substitutes for clinical use. However, many of these scaffolds may not show suitable properties when they are exposed to physiologic vascular environments, and they may fail eventually because of some unexpected conditions. Electrospinning technology offers the potential for controlling the composition, structure, and mechanical properties of scaffolds. In this study, a tubular scaffold (inner diameter = 4.5 mm) composed of a polylactide (PLA) fiber outside layer and a silk fibroin (SF)–gelatin fiber inner layer (PLA/SF–gelatin) was fabricated by electrospinning. The morphological, biomechanical, and biological properties of the composite scaffold were examined. The PLA/SF–gelatin composite tubular scaffold possessed a porous structure; the porosity of the scaffold reached 82 ± 2%. The composite scaffold achieved the appropriate breaking strength (1.28 ± 0.21 MPa) and adequate pliability (elasticity up to 41.11 ± 2.17% strain) and possessed a fine suture retention strength (1.07 ± 0.07 N). The burst pressure of the composite scaffold was 111.4 ± 2.6 kPa, which was much higher than the native vessels. A mitochondrial metabolic assay and scanning electron microscopy observations indicated that both 3T3 mouse fibroblasts and human umbilical vein endothelial cells grew and proliferated well on the composite scaffold in vitro after they were cultured for some days. The PLA/SF–gelatin composite tubular scaffolds presented appropriate characteristics to be considered as candidate scaffolds for blood vessel tissue engineering. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study on the properties of the electrospun silk fibroin/gelatin blend nanofibers for scaffolds

Silk fibroin (SF)/gelatin blend nanofibers membranes as scaffolds were fabricated successfully via electrospinning with different composition ratios in formic acid. The formation of intermolecular hydrogen bonds and the conformational transition of SF provided scaffolds with excellent mechanical properties. FTIR and DTA analysis showed the SF/gelatin nanofibers had more β‐sheet structures than the pure SF nanofibers. The former's breaking tenacity increased from 0.95 up to 1.60 MPa, strain at break was 7.6%, average fiber diameter was 89.2 nm, porosity was 87%, and pore diameter was 142 nm. MTT, H&E stain, and SEM results showed that the adhesion, spreading, and proliferation of human umbilic vein endothelium cells (HUVECs) and mouse fibroblasts on the SF/gelatin nanofibers scaffolds were definitely better than that on the SF nanofibers scaffolds. The scaffolds could replace the natural ECM proteins, support long‐term cell growth, form three‐dimensional networks of the nanofibrous structure, and grow in the direction of fiber orientation. Our results prove that the addition of gelatin improved the mechanical and biological properties of the pure SF nanofibers, these SF/gelatin blend nanofiber membranes are desirable for the scaffolds and may be a good candidate for blood vessel engineering scaffolds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

聚碳酸酯型水性聚氨酯分散体的合成与性能研究

采用聚碳酸酯二元醇Desmophen C与TDI合成了水性聚氨酯分散体。拉伸试验结果表明,乳胶膜具有优异的拉伸强度(高达60 MPa)和断裂伸长率(高达600%)。研究了软段分子量、软段用量对聚碳酸酯聚氨酯力学性能和微观相分离结构的影响。结果表明,随着软段用量的增加,乳胶膜的断裂强度迅速下降,断裂伸长也有所下降。不同分子量的聚碳酸酯也具有相同的规律。但相同软段用量,随着分子量的增加,断裂强度并没有下降,反而有所上升,且断裂伸长略有下降。同时聚碳酸酯型水性聚氨酯乳胶膜具有优异的水解稳定性。     

Tailored electrospun small-diameter graft for vascular prosthesis

There is an unmet need for engineering small vascular graft that can be anastomosed without inducing thrombosis. The objective of this work is to fabricate tubular graft with 2?mm of diameter with biomimetic mechanical and biological properties. Poly(ε-caprolactone) and poly(glycerol sebacate) blends with different concentrations and ratios are used to fabricate fibrous grafts using electrospinning process. Porous and degradable scaffolds with enhanced mechanical properties and comparable suture retention to the native human artery are fabricated. Scaffold–blood interaction revealed good anticoagulation properties. The fabricated constructs can serve as biocompatible and hemocompatible vascular graft with enhanced mechanical properties.     

Silk‐inspired polyurethane containing glyalaglyala tetrapeptide. III. morphological,thermal, and mechanical features of electrosprayed and electrospun deposition

Morphological, thermal, and mechanical features of electrosprayed and electrospun deposition of the silk‐inspired polyurethane (PU) containing GlycineAlanineGlycineAlanine (GlyAlaGlyAla, the featured peptide sequence of silkworm silk fibroin) tetrapeptide, which was synthesized by the traditional liquid‐phase peptide synthesis method and the classical two‐step polymerization method using Boc‐protected amino acids and diisocyanates as starting materials, were characterized. The results show that the synthesized silk‐inspired PU dissolved in tetrahydrofuran (THF) can be easily electrosprayed or electrospun into the film form, although its molecular weight ranging from 13,000 to 15,000 is quite low. Elastomeric fibrous membranes with surface morphologies of “droplets,” “bead‐on‐string,” and “nonwoven fibers” have been obtained by electrospraying and electrospinning the silk‐inspired PU/THF solution of varying concentrations. The thermograms confirm high thermostability of the silk‐inspired PU between 350 and 400°C due to the polar peptide linkages. The tanδ peak of dynamic mechanical analysis curve corresponding to its glass transition temperatures is detected at ?34.3°C. Its elongation at break is about 140–150%, and the breaking tensile strength ranges from 22 to 27 MPa, which is consistent with the data of other PUs containing l ‐alanine residue. Information provided by this study can be used to better understand the correlation between the natural and man‐made silk polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40245.     

Air‐dried 3D‐collagen–chitosan biocomposite scaffold for tissue engineering application

Collagen–chitosan scaffolds of different compositions were developed using emulsion air‐drying method. The scaffolds prepared adding 10–30 wt% of chitosan to collagen improved the mechanical properties of the composite scaffold, and 7:3 ratio (collagen :chitosan) was found to be a better composite having a tensile strength of 13.57 MPa with 9% elongation at break. The water‐uptake characteristics were performed at different pH and found to be ameliorated for the composite scaffolds compared to pure collagen and chitosan scaffold, respectively. The pores ranging from 100 to 300 μm were well interconnected, and their distribution was fairly homogeneous in the scaffold as observed through scanning electron microscopy. Furthermore, the scaffold decreased the bacterial counts and supported fibroblasts attachment and proliferation, thus demonstrating this composite to be a good substrate for biomedical application.POLYM. COMPOS., 33:2029–2035, 2012. © 2012 Society of Plastics Engineers     

A bilayered scaffold based on RGD recombinant spider silk proteins for small diameter tissue engineering

A bilayered scaffold was fabricated via electrospinning layer‐by‐layer with the inner layer composed of blend fibers of spider silk protein and gelatin (pNSR16/Gt), then the polyurethane (PU) layer on the outside. The physicochemical and biological performance of scaffold were investigated. The pNSR16/Gt‐PU composite nanofibers with interconnected pores was detected a porosity of 88.7 ± 1.5%; with mechanical properties, including an appropriate permeability of 6.8 ± 0.2 ml min⁻¹ cm⁻², breaking strength (24.6 ± 3.6 MPa) and elasticity up to 145 ± 3.8% strain, and burst pressure reached 276 ± 7.1 kPa as well as an accepted suture retention strength (4.9 ± 0.8 N), optimized to mimic the nature artery. The pNSR16/Gt‐PU bilayered scaffold also proved to be capable to support cell growth and proliferation of Sprague‐Dawley rat aortic endothelial cells by 242 ± 10% (7 days vs. control). After all, the intimal surface promotes endothelialization and being highly anti‐thrombogenic, while the mismatch in mechanical properties outside induces intimal hyperplasia, it is desirable to develop a bioactive material with improved mechanical properties for small‐diameter vascular graft. POLYM. COMPOS., 37:523–531, 2016. © 2014 Society of Plastics Engineers     

聚氨酯/层状双金属氢氧化物复合膜的制备和性能研究

利用静电纺丝设备制备了层状双金属氢氧化物(LDH)增强的聚氨酯(PU)电纺复合膜(复合膜),采用扫描电子显微镜(SEM)、广角X射线衍射(WAXD)、电子万能试验机、差热式扫描分析仪(DSC)和热重分析仪(TG)对PU/LDH复合膜的形貌、力学性能以及热稳定性进行了分析。研究结果表明,添加少量的LDH就能使复合膜强度有明显提高,当LDH含量为1%(质量分数)时复合膜的强度提高到16.2 MPa左右,相对电纺制备的纯PU膜,提高幅度约为217%;而PU/LDH复合膜的断裂伸长率保持了较高的水平,达到了约165%。扫描电镜(SEM)显示,加入LDH有利于电纺,所得纤维的直径有小幅度下降。WAXD分析结果表明,LDH在PU中并未形成插层结构,LDH与PU的混合类似于传统共混过程。DSC分析结果表明,LDH对PU软段的玻璃化转变温度无显著影响,但是对PU硬段的结晶有一定的促进作用。TG分析结果表明,复合电纺膜的起始分解温度相对PU电纺膜有一定程度的降低。     

PLGA/SF blend scaffolds modified with plasmid complexes for enhancing proliferation of endothelial cells

Biomimetic scaffolds have been investigated for vascular tissue engineering for many years. However, the design of an ideal biodegradable vascular scaffold is still in progress. The optimization of poly(lactide-co-glycolide)/silk fibroin (PLGA/SF) blend composition was performed to provide the designed scaffolds with adequate mechanical properties and favorable biocompatibility for the intended application. By systematically varying the weight ratio of PLGA and SF, we could control fiber diameter and hydrophilicity as well as mechanical properties of the fibrous scaffolds. These scaffolds with a weight ratio of PLGA/SF at 70/30 exhibited excellent performance, such as tensile strength of 1.5 ± 0.1 MPa, and elongation at break of 77.4 ± 6.4%. Therefore, PLGA/SF scaffold with a weight ratio of 70/30 was chose as the matrix because it matches at best the mechanical demands for application in vascular tissue engineering. In order to promote the endothelialization of electrospun scaffolds, we used pEGFP-ZNF580 plasmid (pZNF580) complexes to modify the electrospun scaffolds by electrospraying technique. pZNF580 complexes were prepared from pZNF580 and microparticles (MPs) of amphiphilic copolymer methoxy-poly(ethylene glycol)-block-poly(3(S)-methyl-2,5-morpholinedione-co-glycolide)-graft-polyethyleneimine. Negatively charged PLGA/SF fibers adsorbed the positively charged MPs via physical deposition and electrostatic force. Scanning electron microscope image indicated the forming of composite scaffold and MPs did not change fiber’s shape and 3-D structure. Cell culture experiments demonstrated that the scaffolds modified with MPs/pZNF580 complexes could promote human umbilical vein endothelial cell growth and inhibit human umbilical artery smooth muscle cell proliferation. Our results indicated that the composite scaffolds with MPs/pZNF580 complexes could be used as a potential scaffold for vascular tissue engineering.     

聚己内酯—共聚醚制备聚氨酯弹性体的研究

以聚己内酯、四氢呋喃－环氧丙烷共聚醚、甲基二异氰酸酯、ＭＯＣＡ等为原料,制备了浇注型聚氨酯弹性体了聚己内酯与共聚醚的比例、ＮＣＯ质量分数、增塑剂与ＭＯＣＡ用量比例对弹性体力学性能的影响。以最佳工艺条件制得的弹性体,其性能为：邵尔Ａ型硬度为５７￣５８,３００％模量３．８￣３．９ＭＰａ,拉伸强度１８．５￣１９．５ＭＰａ,扯断工率４５０￣４６０％,撕裂强度２８￣３０ｋＮ／ｍ。     

静电纺PLGA管状支架的构建及其生物力学性能

以具有良好生物相容性、生物可降解性的聚丙交乙交酯(PLGA)为原料,以高速旋转的滚轴为收集装置,通过静电纺丝法,制备PLGA管状支架(d=6mm)。研究不同工艺及乙醇处理对PLGA管状支架形貌结构、微细结构和生物力学性能的影响。结果表明:当纺丝液质量分数为7%,滚轴转速为1500r/min时,可制得纤维形貌规整、分布均匀,直径为(1660±218)nm,孔隙率为80.6%的PLGA管状支架;经乙醇处理后,其孔隙率减小,玻璃化温度和热分解温度提高,热稳定性增强;断裂强度、爆破强度及缝合强力均显著提高。     

In vitro assessment of dual-network electrospun tubes from poly(1,4 cyclohexane dimethylene isosorbide terephthalate)/PVA hydrogel for blood vessel application

The fabrication of artificial blood vessel remains an ongoing challenge for cardiovascular tissue engineering. Full biocompatibility, proper physiological, and immediate availability have emerged as central issues. To address these issues, the dual-network composite scaffolds were fabricated by coating the electrospun nanofibers-based tubes with poly(vinyl alcohol) (PVA) hydrogel, which could increase the cell viability and show the potential for controlling the composition, structure, and mechanical properties of scaffolds. Herein, the tubular scaffolds having an inner diameter of 2 mm, were composed with poly(1,4 cyclohexane dimethylene isosorbide terephthalate)/PVA. The morphology examination showed that tubular structure was dimensionally stable and suitable for an artificial blood vessel. Fourier transform infrared spectra, wetting behavior, stress–strain behavior, and Thiazolyl Blue Tetrazolium Bromide (3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide) analysis also showed that the composite scaffolds have good chemical interactions between poly(1,4 cyclohexane dimethylene isosorbide terephthalate) (PICT) and PVA, blended PICT/PVA tubes showed the appropriate wetting behavior, it achieved the appropriate breaking strength and adequate pliability up to 47.5% and in vitro assessment showed that blended PICT/PVA scaffolds have the appropriate cell viability and nontoxic, respectively. On the basis of characterizations results, it was concluded that resultant scaffolds would be addressed to fulfill the requirements such as biocompatibility, dimensional stability, adequate elongation, breaking strength, immediate availability, and proper for physiologically. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47222.     

纳米羟基磷灰石增强聚己内酯/明胶纤维膜的制备及其性能

引导组织再生膜在引导组织再生术中发挥着关键作用，高性能的引导组织再生膜能更好地促进组织再生修复。本文以纳米羟基磷灰石（n-HA）、聚己内酯（PCL）、明胶（Gel）为原料，通过静电纺丝法制备了不同含量n-HA增强的PCL/Gel/n-HA纤维膜，并对其形貌、组成、力学性能及降解性能进行了研究。SEM结果表明，纤维膜中的纤维形态良好，纤维直径大致分布于200～400nm之间，交联后纤维直径明显增加；TEM结果表明，n-HA较均匀分散在纤维中，随着n-HA含量的增加，n-HA在纤维膜表面发生聚集。力学测试结果表明，随着n-HA含量的增加显著提高了纤维膜的拉伸强度和断裂伸长率，当n-HA含量约为15%时，其拉伸强度和伸长率分别达到9.18MPa和180%。n-HA加入后，纤维膜的降解速率明显降低，n-HA含量约为15%的复合纤维膜体外降解12周以后约降解25%。本文制备的PCL/Gel/n-HA纤维膜的力学性能和降解速率能满足临床对引导组织再生膜的性能要求。     

异氰脲酸酯基团对聚氨酯弹性体性能影响研究

引入异氰脲酸酯基团可提高聚氨酯弹性体的耐热性能,但同时对其他性能有一定影响。通过改变NCO含量考察异氰脲酸酯基团对聚氨酯弹性体的力学性能及耐溶剂性能的影响。力学性能测试结果表明,其硬度、拉伸强度和撕裂强度均在NCO质量分数为8％时达到极大值,分别为邵A60、10．33MPa和48．84kN／m,扯断伸长率随NCO含量增加单调减小,100％定伸强度单侧增大;耐溶剂实验表明,聚氨酯弹性体在NCO质最分数为8％时耐溶剂性能最好。     

电纺制备聚乳酸/聚醚砜复合纳米纤维膜及性能研究

采用同轴静电纺丝制备聚乳酸/聚醚砜(PLA/PES)复合纳米纤维膜，通过改变皮层溶液的挤出速率以及在芯层溶液中分别添加石墨烯（GO）、碳纳米管(MWCNTs)、埃洛石（HNTs）纳米粒子，制备了系列皮芯结构的复合纳米纤维膜。通过扫描电子显微镜、纤维强伸度仪、接触角测定仪等仪器测试表征了复合纳米纤维膜的纤维结构、拉伸强度、疏水性以及吸油倍率等性能。结果表明，制备的复合纳米纤维膜的接触角均大于130 °，表现出较好的亲油疏水性；当往芯液中添加石墨烯(GO)时，纳米纤维膜的吸油性能、拉伸性能最好，在甘油中的吸油倍率可达到67.61倍，食用油中可达到48.02倍，纵向断裂强度为62.68 MPa，横向断裂强度为43.98 MPa，横向断裂伸长率可达到697.76 %。     

Toughening of polylactide via in situ formation of polyurethane crosslinked elastomer during reactive blending

Polylactide (PLA)/polyurethane (PU) composites were prepared by reactive blending method with in situ formation of PU particles via the reaction between polyester polyol (PPG) and toluene‐2,4‐diisocyanate (TDI). The interfacial compatibility and adhesion between the PLA and PU phases were greatly improved by the reaction of the terminal hydroxyl groups of PLA and N?C?O groups of TDI forming graft copolymer, as confirmed by FTIR spectroscopy. The elongation at break and notch impact strength of PLA/PU composites increased considerably with increasing PU content, and the tensile strength of PLA/PU composites decreased slightly compared with that of pure PLA. Upon addition of 12 wt % PU, the elongation at break and notch impact strength increased to 175.17% and 10.96 kJ/m², respectively, about 27 times and 5.4 times greater than the corresponding values for the pure PLA. The tensile strength decreased only slightly to 48.65 MPa. The excellent interfacial adhesion, the dispersed PU elastomeric particles acting as stress concentration areas, and the triggering of large matrix shear yield as well as many fibrils by internal cavitation were the main mechanical toughening mechanisms. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44383.     

Fabrication of Biodegradable Polyurethane Foam Scaffolds with Customized Shapes and Controlled Mechanical Properties by Gas Foaming Technique

Poly(ε-caprolactone) (PCL)-based polyurethane (PU) foam scaffolds with different mechanical properties are fabricated using a gas foaming technique to use as porous substitutes for ear or bone with cartilage. PCL diol or triol is used as a polyol in PU foam for biocompatibility and biodegradation, with an aqueous gelatin solution as a blowing agent. The highly porous inner and outer structures of the scaffolds are developed by employing a silicone surfactant and sulfuric acid, respectively. The PU scaffolds prepared by PCL diol show ductile and flexible properties, whereas the PU scaffolds prepared by PCL triol exhibit high compression strength. In vitro test reveals the low toxicity of the PU scaffolds and the high ALP activity of MC3T3-E1 cells in the PU scaffold prepared by PCL triol. By taking advantage of the difference in mechanical properties, customized PU scaffolds with ear or bone shapes are fabricated using a silicone mold. The PU scaffolds with two compartments of PCL diol and triol (corresponding to cartilage and bone, respectively) are fabricated as a substitute for bone with cartilage. It is believed that the PU scaffolds with highly porous structure and controlled mechanical properties have wide potential application for tissue engineering.     

Preliminary Study for Vascular Tissue Engineering by Electrospinning Angelica Polysaccharide (ASP)/PLA Microfibrous Scaffolds

The purpose of this investigation was to develop the feasibility of utilizing Angelica polysaccharide in vascular tissue engineering area. Angelica polysaccharide and poly lactic acid (PLA) microfibrous mixed in different ratios were prepared with electrospinning apparatus. A series of detection technology (SEC-LLS, SEM, MTT, paraffin sections, mechanical test) was used to characterize and determine the property of composite scaffold such as molecular weight, biomechanical, bioactivity, cytotoxicity, biocompatibility, and biodegradability. The scaffolds exhibited similar mechanical property to the native tissues, possessed good biological compatibility and decreased platelet adhesion/aggregation rate. All these showed the excellent potentiality of Angelica polysaccharide in vascular tissue engineering.     

无溶剂聚氨酯改性环氧树脂隔热涂料的研制

介绍了无溶剂聚氨酯改性环氧树脂及无溶剂隔热涂料的制备方法。对树脂、涂料的热性能进行了评价。结果显示,无溶剂聚氨酯改性环氧树脂隔热涂料的拉伸强度大于10MPa,断裂伸长率大于3%,附着力大于10MPa,室温下比热容1.26kJ/(kg·K),隔热参数为0.07kg2/(m4·s),隔热效率0.175W/(m2·K),综合性能优良。     

Comparative study on eri silk and mulberry silk fibroin scaffolds for biomedical applications

Mulberry silk fibroin is being used as biomaterial for tissue engineering applications. In the present work, comparisons are made between mulberry and eri silk fibroin scaffolds prepared by electrospinning method. The scaffolds are treated with ethanol to improve their dimensional stability, and the physical and chemical properties of the scaffolds are assessed using thermogravimetric analyzer (TGA), differential scanning calorimetry, Fourier transform infrared spectroscopy and X-ray diffractometry. The FTIR spectra confirm the structural change of silk fibroin from α-helical to β-sheet structure when mulberry and eri silk scaffolds are treated with ethanol. The thermal stability of the eri silk scaffold is found to be better than that of mulberry silk. Ethanol-treated eri silk displays higher tensile stress than the ethanol-treated mulberry silk. The hemolysis percentages of eri silk and mulberry silk scaffolds are found to be 1 and 3 %, respectively. While the platelet adhesion on eri silk fibroin scaffold is found to be lower than that of mulberry silk fibroin scaffold, the cell attachment, binding and spreading of L6 fibroblast cells on the eri silk scaffold are better than those on the mulberry silk fibroin, and the cell viability is found to be better on eri silk fibroin scaffold.