三种不同溶剂静电纺丝素纳米纤维的研究进展

静电纺丝素纳米纤维支架材料在组织工程领域具有广阔的应用前景。本文综述了三种不同溶剂静电纺丝素纳米纤维支架材料及其在组织工程领域的研究进展。     

超临界二氧化碳相转化技术制备组织工程支架研究进展

组织工程支架是组织工程研究的关键要素之一。然而,传统制备方法存在操作条件复杂或有机溶剂残留量高等问题。本文基于超临界二氧化碳相转化技术操作条件温和、可以将相分离与干燥过程合二为一、有效地去除有机溶剂等优点,简要介绍了超临界二氧化碳相转化技术中应用的组织工程支架材料,具体阐述了制备出具有致密无孔结构、孔洞结构以及三维纳米纤维结构的组织工程支架的研究进展。随后对其目前存在的不足,如该项技术缺少系统的理论研究、部分制备出的支架不利于传质、负载生长因子和细胞粘附等问题提出了可能的解决方案。最后对超临界二氧化碳相转化技术制备具有类似细胞外基质结构和功能、孔洞相互贯通、微观粗糙纳米纤维表面的组织工程支架进行了展望。     

纳米纤维应用于组织工程的研究进展

组织工程支架的关键作用是起到引导细胞繁殖、生长,促进组织修复的一个过程。纳米纤维支架由于具有特殊的纳米效应,而更有利于细胞的黏附、增殖、功能化,因而被广泛应用于组织工程。本文分别介绍了纳米纤维支架在各类组织工程中应用,包括皮肤和创伤敷料组织工程、血管组织工程、神经组织工程、骨组织工程、软骨组织工程中应用的研究进展,同时介绍了纳米纤维支架药物控制释放中的应用。指出目前纳米技术还不成熟,需要从制备工艺的优化、基因工程的引入及纳米材料安全性能的科学评价等几方面解决纳米纤维支架在组织修复工程中面临的问题。     

超临界CO_2技术制备组织工程支架材料的研究进展

从原料、制备方法以及支架材料的生物活性评价等方面对超临界CO_2技术在组织工程支架材料制备中的应用进行了综述,指出了存在的问题,并对此制备技术的发展及制备产品的应用进行了展望。     

组织工程支架的最新研究

综述了最近几年国内外组织工程支架的研究状况，重点介绍了组织工程支架的制备技术（包括浇铸／沥滤致孔、低热高压、分相、超临界CO2、静电纺丝等），选用材料以及在皮肤、软骨、骨和心血管等组织修复中应用的最新进展。     

热致相分离技术制备组织工程支架

用生物可降解材料制备细胞生长支架是组织工程的关键技术之一,而热致相分离技术是制备生物可降解三维多孔支架的重要方法.综述了凝胶浇铸、热致凝胶化、乳化/冷冻干燥、固液相分离和液液相分离等几种相分离技术的原理及应用,并预测了相分离技术的应用前景.     

组织工程支架材料及制备方法研究现状

组织工程支架已经广泛应用于皮肤、软骨、心血管、心脏等各种组织的修复中.组织工程材料分为天然材料和合成材料两大类,均需要具备良好的生物相容性.组织工程支架的制备方法主要有相分离、冷冻干燥、发泡、颗粒浸出、静电纺丝、3D打印等.现对组织工程支架所用到的材料、制备方法以及组织工程支架的应用进行综述.     

纤维素组织工程支架的研究进展

纤维素具有良好的生物相容性和可降解性,在生物组织工程领域作为支架材料的研究近年来受到研究者的关注。文章介绍了组织工程支架的性能要求,以及纤维素、细菌纤维素用于组织工程支架的研究现状。针对组织工程支架的分子设计、纳米化趋势,提出了纳米纤维素纤维用于组织工程支架的设想。并综述了纳米纤维素纤维制备的最新研究进展,预测了未来纤维素组织工程支架的发展趋势及前景。     

聚癸二酸丙三醇酯的合成及电纺支架的制备

通过熔融共缩聚反应,将1∶1和1∶2两种摩尔比的丙三醇和癸二酸合成可生物降解的聚癸二酸丙三醇聚酯弹性体(PGS),并对其性能进行测定,1∶1组PGS与左旋聚乳酸(PLLA)共混,应用静电纺丝方法构建组织工程支架。结果表明,PGS弹性体具有优异的亲水性能和可生物降解性能,PLLA改性电纺的PGS支架符合组织工程支架材料的基本要求。     

微观结构与组织工程丝素支架研究进展

丝素蛋白因其具有良好的生物相容性、生物可降解性以及卓越的力学性能而被广泛应用于组织工程。为了促进丝素支架更利于细胞的黏附和增殖、促进新的细胞外基质生成、组织向内生长以及利于营养物质及代谢产物的运输等,丝素支架微观结构的构建仍是组织工程的一个重大挑战。本文着重围绕丝素支架的微观结构展开,介绍了多孔结构、纤维结构、多孔-纤维结构和水凝胶结构近年来在组织工程中的应用,从不同支架结构制备方法及功能方面并结合作者实验相关工作对比分析了不同支架结构的优势和存在的问题以及对细胞的影响,指出应从分子水平及原子水平上研究天然组织的结构来精准、有效地体外模拟构建组织工程丝素支架。     

Hierarchical bioceramic scaffold for tissue engineering: A review

Bioceramic scaffolds have a promising application in bone-tissue engineering field. However, bioceramic scaffolds exhibit low fracture toughness; hence, to overcome this problem, hierarchical bioceramic scaffold or bioceramic scaffolds coated with polymer are produced. Starting with the fundamental requirements for bioceramic scaffold, this article provides detailed information on recent developments of method to produce porous bioceramics scaffold and hierarchical bioceramic scaffold. Chemical modifications to enhance interfacial adhesion and formation of interpenetrating network structures between the bioceramic scaffold and the natural polymer layer are discussed in this article. Areas of future research are highlighted at the end of this review.     

Ultrasonication‐Induced Modification of Hydroxyapatite Nanoparticles onto a 3D Porous Poly(lactic acid) Scaffold with Improved Mechanical Properties and Biocompatibility

A 3D porous poly(lactic acid) (PLA) scaffold with high porosity and well‐connected pores is fabricated using a vacuum‐assisted solvent casting technique. Its surface is modified with hydroxyapatite (HA) nanoparticles using ultrasonication to prepare an HA‐modified PLA/HA scaffold. For reference, an HA‐blended (b‐PLA‐HA) scaffold is fabricated via the solution blending method. The morphology, porosity, hydrophilicity, swelling ratio, mechanical properties, and cell viability of the PLA, b‐PLA‐HA, and PLA/HA scaffolds are systematically studied. The results show that HA nanoparticles are successfully introduced onto the surface of the PLA/HA scaffold, and strong interactions occur between the HA nanoparticles and the PLA matrix. The PLA/HA scaffold still has a high porosity of more than 85% after ultrasonication. The hydrophilicity and mechanical properties of the PLA/HA scaffold are significantly higher than those of the PLA and b‐PLA‐HA scaffolds. Compared with the PLA and b‐PLA‐HA scaffolds, the attachment and growth of mouse embryonic osteoblasts cells (MC3T3‐E1) cultured on the PLA/HA scaffold significantly improve, due to most HA nanoparticles on the surface, resulting in a good and direct interaction between the cells and the scaffold. Therefore, the PLA/HA scaffold possesses great potential to be used as a tissue engineering scaffold.     

Physico‐optical properties of a crosslinked hyaluronic acid scaffold for biomedical applications

Optical techniques are increasingly employed for monitoring cell–matrix interactions in suitably prepared 3D scaffolds. The ability of designing and realizing synthetic extracellular matrix with well‐controlled optical properties is a crucial need in this field. For this purpose, a crosslinked hyaluronic acid (HA) scaffold is prepared. Fourier transform infrared and ultraviolet–visible spectroscopies enable to monitor the scaffold preparation process and to evidence scaffold high transparency and low fluorescence in the visible range. 3D optical characteristics of the HA scaffold are tested by two‐photon microscopy (TPM) imaging of embedded fluorescent microbeads and alive keratinocytes labeled with vital PKH67 dye at different depths from the scaffold surface. Some useful indications about the potentiality of TPM measurements for the determination of attenuation coefficient of turbid media are also reported. Moreover, the use of the presented HA scaffold for preparing tissue phantoms for fluorescence imaging or diffuse imaging is proposed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45243.     

Surface Modification of Electrospun TPU Nanofiber Scaffold with CNF Particles by Ultrasound‐Assisted Technique for Tissue Engineering

A straightforward, fast, and versatile technique is developed to fabricate nanofibrous scaffold with excellent hydrophilicity, mechanical properties, and biocompatibility for tissue engineering. The thermoplastic polyurethane (TPU) nanofiber is fabricated by utilizing electrospinning, and then its surface is modified through simply immersing it into cellulose nanofibrils (CNF) dispersion and subjecting to ultrasonication. The results show that the CNF particles are successfully absorbed on the surface of TPU nanofiber. By introducing CNF particles on the surface of TPU nanofiber, the hydrophilicity, mechanical properties of fabricated CNF‐absorbed TPU scaffold are significantly increased. Additionally, the adhesion and proliferation of human umbilical vein endothelial cells cultured on CNF‐absorbed TPU scaffold are prominently enhanced in comparison with those of cultured on TPU scaffold. These findings suggest that the ultrasound‐assisted technique opens up a new way to simply and effectively modify the surface of various scaffolds and the modified scaffold could be shown a great potential in tissue engineering.     

Fabrication of quaternary composite scaffold from silk fibroin,chitosan, gelatin,and alginate for skin regeneration

Quaternary composite scaffold consisting of chitosan, alginate, gelatin, and silk fibroin, was fabricated by applying foaming method, for tissue engineering applications. The fabricated scaffold was evaluated for its applicability in skin tissue regeneration. The environmental scanning electron microscopy (ESEM) showed the presence of interconnected pores, mostly spread over the entire surface of the scaffold with mean pore size 92±11.8 μm and the porosity 88%. The scaffold showed good mechanical stability under physiological conditions as determined by short term mechanical stability testing. In vitro scaffold‐degradation study showed no degradation at day 1 and from day 3 scaffold starts degrading. The degradation of the composite scaffold after 28 days was 38%. Less degradation rate of the scaffold might be beneficial, as it can provide sufficient time for the formation of neo‐tissue and extracellular matrix (ECM) during tissue regeneration. In vitro cell culture studies by seeding L929 mouse fibroblast cells over composite scaffold showed good cell viability, proliferation, and adhesion as indicated by 3‐(4,5‐dimethylthiazol‐2‐yl‐2,5‐diphenyltetrazolium bromide) (MTT) assay and ESEM of cell‐scaffold construct. Giemsa staining of L929 fibroblast cells over the scaffold showed fibroblastic morphology of L929 cells, having elongated cells with nuclei and faint cytoplasm, and these cells are positive for Oil Red stain and negative for Alizarin Red staining—indicating that they maintained their dermal fibroblastic phenotype and were not differentiated into any other cell types in presence of composite scaffold. Results of histological staining supports growth and viability of L929 fibroblasts over scaffold, thereby proving the great prospective of this scaffold for skin tissue engineering applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42743.     

Development of biodegradable scaffold using polylactic acid and polycaprolactone for cardiovascular application

The limitations of newly synthesized biodegradable stents are low mechanical strength, fracture stiffness, and fast degradability of the polymers. A cylindrical polymeric scaffold was proposed in combination of polylactic acid and polycaprolactone. The tensile strength of the blend was increased twice, though elongation has reduced threefold. The blend illustrated no chemical interaction between polymers. The scaffold was coated with docetaxel, and sustained release profile was observed for 56 days. The degradation of the scaffold was evaluated through change in mechanical properties, weight variation, and morphological studies. The developed hemocompatible polymeric scaffold may be used as for the cardiovascular application.     

Engineered polymer-based scaffold as an implantable therapeutic vaccine against melanoma

Although tumor-antigen-based therapeutic cancer vaccines are a potential cancer immunotherapy strategy, recent clinical trials show low efficacy for multiple reasons. One method that has been recently investigated to improve the efficacy of therapeutic cancer vaccines is the development of implantable vaccines for sustained delivery of antigens and CD8 T cell activation. Here, we optimized the composition for an implantable vaccine scaffold composed of alginate, polyvinyl alcohol, and poly(methyl vinyl ether- alt-maleic anhydride) loaded with tumor antigens. Considering the adjuvant property of aluminum compounds, aluminum ion was used to crosslink alginate in the scaffold. The scaffold showed an effective antigen incorporation efficiency of 90.34 ± 0.55% using ovalbumin as the model antigen and 89.67 ± 2.8% using B16-F10 cell lysate. SEM analysis of the scaffold showed pore size ranging from 5 to 10 μm. Cell viability analysis using mouse RAW 264.7 macrophages proved the cytocompatibility of the scaffold. In vitro antigen release studies using ovalbumin showed 8.42% release for a period of 14 days. In vivo antitumor analysis carried out in subcutaneous mouse B16-F10 melanoma model demonstrated that the scaffold vaccine reduced the rate of tumor growth and improved survival in tested animals. The median survival time increased from 29 days in untreated animals to 58 days in scaffold vaccine-implanted animals.     

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.     

Sandwich-Like Gelatin/Polycaprolactone/Polyvinyl Pyrrolidone 3D Model with Significantly Improved Cartilage Cells Adhesion and Regeneration

A novel sandwich-like composite 3D model integrated with deposited gelatin film and printed polycaprolactone (PCL)/polyvinyl pyrrolidone (PVP) scaffold is proposed for 3D cartilage cell culture. The 3D model includes three layers, top scaffold, middle gelatin film, and basal slide. The printed scaffold layer mimicking extracellular matrix is employed to provide 3D regeneration architecture; gelatin film layer is used for fixing printed scaffold and catching falling cells. Electrospray and electrohydrodynamic jet printing technologies are combined to construct sandwich-like composite 3D model. The blended constructing processes are investigated thoroughly both theoretically and experimentally. The retained charges on the gelatin film are influenced the electric field distribution and jet behaviors during printing. The characteristics of gelatin film and composite scaffold are studied. The thickness, surface roughness, and planeness of one layer of deposited gelatin film are 400 nm, 22 nm, and 2.27 µm; the size of printed PCL/PVP composite fiber is 10 µm. The fabricated sandwich-like composite 3D model is proved to facilitate adhesion and ingrowth of cartilage cells.     

Effect of Methyl Group on Acyclic Serinol Scaffold for Tethering Dyes on the DNA Duplex Stability

Acyclic serinol derivatives are useful scaffolds for tethering dyes within DNA duplexes. Here we synthesised an inverse l ‐threoninol (il ‐threoninol) scaffold and compared its effect on DNA duplex stability to other acyclic artificial nucleic acid scaffolds that are based on d ‐threoninol, l ‐threoninol, and serinol. When planar trans‐azobenzene was incorporated into the DNA duplex through a single bulge‐like motif (the wedge), the il ‐threoninol scaffold stabilised the duplex most efficiently. When scaffolds were incorporated in complementary positions (dimer motif) or in three adjacent positions (cluster motif), d ‐threoninol was the most stabilising. CD spectra indicated that the effect of scaffold on the duplex stability was closely related to the winding induced by each scaffold. When trans‐azobenzene was photo‐isomerised to non‐planar cis‐azobenzene, il ‐threoninol destabilised the duplex most strongly, irrespective of the number of artificial residues incorporated. The properties of the il ‐threoninol scaffold make it a useful tether for dyes or other functionalities.