细菌纳米纤维素/聚乙烯醇小径人工血管的制备及其表征

细菌纳米纤维素(bacterial nano-cellulose, BNC)有着良好的生物相容性和力学性能,已被广泛研究用于人工血管等生物医学领域。当纯的BNC凝胶管用于小口径人工血管时,缝合强度等力学性能以及长期抗凝血性等方面不足。为改善以上性能,本研究首次采用压力注射聚乙烯醇(polyvinyl alcohol, PVA)与相分离技术相结合的方法制备BNC/PVA复合管,同时对复合管进行了理化性能与生物相容性表征。结果表明BNC/PVA复合管的轴向拉伸性能、缝合强度、抗渗漏性、爆破压指标均大于BNC管。复合管减少了血小板的粘附,延长了血浆复钙时间,抗凝性优于BNC管?BNC/PVA复合管对于HUVECs生长增殖无毒害作用。以15%PVA初始浓度复合的BNC/PVA15%管具有良好的力学性能、血液相容性和细胞相容性,表明该复合管在小口径人口血管领域具有良好的应用前景。     

纳米纤维素的制备与表征

以微晶纤维素为原料,通过硫酸酸解制备获得了纳米纤维素。实验优选获得了酸解制备纳米纤维素的优化条件为:硫酸初始浓度35%,反应温度40℃,酸解时间90 min,此优化条件下,纳米纤维素的产率可达83.55%;SEM和TEM观察产物的形态外貌,确定为纳米级纤维素;XRD分析显示纳米纤维素的结晶度要高于微晶纤维素,而TG分析显示NCC的热稳定性要低于微晶纤维素。     

纳米纤维素的制备与表征

以微晶纤维素为原料,通过硫酸酸解制备获得了纳米纤维素。实验优选获得了酸解制备纳米纤维素的优化条件为:硫酸初始浓度35%,反应温度40℃,酸解时间90 min,此优化条件下,纳米纤维素的产率可达83.55%;SEM和TEM观察产物的形态外貌,确定为纳米级纤维素;XRD分析显示纳米纤维素的结晶度要高于微晶纤维素,而TG分析显示NCC的热稳定性要低于微晶纤维素。     

纤维素纳米纤维的生产及其应用

纳米纤维是拉伸纤维素链的半结晶纤维束,它们的热膨胀率像石英一样低,而其强度则是钢的5倍。考虑到石油储量枯竭和地球的环保问题,所以,新开发的纤维素纳米纤维及其应用已经受到了人们的高度关注。文中概述了用植物资源生产纳米纤维的研究工作,及其在聚合物复合材料中的应用。     

竹纳米纤维素晶须的制备

利用硫酸水解竹浆纤维制备纳米纤维素晶须。通过原子力显微镜(AFM)和X射线衍射对纳米纤维素晶须的形貌、结构进行分析和表征,研究不同酸水解时间对纳米纤维素晶须结构的影响。结果表明,用竹浆制备的纳米纤维素晶须为长棒状结构。随着酸水解时间的延长,其长度和直径逐渐减小;在酸水解时间为20 min时无定形区逐渐被降解,其长径比最大,结晶度最高。     

心血管领域的难点及细菌纳米纤维素的应用潜力

心血管疾病（心肌梗死、冠状动脉粥样硬化、高血压等）已成为全球人类死亡的主要原因,这些疾病目前主要依靠药物治疗,严重时需心脏冠脉搭桥等外科手术治疗。文中简述了小口径人工血管及人工心脏瓣膜需求的急迫性以及细菌纳米纤维素（BNC）的特点,回顾了BNC在心血管领域的最新研究进展并预测了今后的发展方向。细菌纳米纤维素因其形状可塑性、具有类细胞外基质的3D纤维网络结构、高持水性、血液和细胞相容性好等优点,在心血管领域中的应用潜力非常突出,为其今后在该领域中的发展奠定了基础。     

沙柳纳米纤维素的制备及表征

以沙柳纤维素为原材料,用氢氧化钠/尿素体系溶解再生的方法制备沙柳纳米纤维素,采用SEM观察微观形貌,用纳米粒度仪分析粒径,采用XRD分析结晶情况,采用FTIR分析表面官能团。结果表明,制得的沙柳纳米纤维素为类球状,平均粒径110 nm,沙柳纳米纤维素为纤维素Ⅱ型结构,结晶度53. 9%,表面存在大量的羟基。     

从Lyocell纤维制备纳米纤维素

介绍了利用Lyocell纤维结构上的特点制备纳米纤维素的研究。包括以Lyocell纤维为原料,在机械外力作用下制备纳米纤维;在酸和氧化物作用下制备纳米球;以Lyocell凝胶为原料制备纳米球。     

纳米纤维素纤维凝胶特性及其应用

纳米纤维素纤维在水溶液中可以通过物理缠绕以及氢键结合的方式形成具有稳定三维网络结构的水凝胶。纳米纤维素水凝胶具有无毒性及良好的生物相容性,在生命科学领域应用前景广阔。而纳米纤维素气凝胶保持凝胶的三维网络结构,其高比表面积、低密度及优异的隔热性能等在建筑、能源电子器件、油水分离等领域也同样有着巨大的应用潜力。本文从纳米纤维素基本特性、纳米纤维素水凝胶、纳米纤维气凝胶研究及应用情况进行了介绍,并分别对纳米纤维素水凝胶与气凝胶的优异性能及应用进展进行了总结。     

纤维素酶解天然棉纤维制备纳米纤维素晶体及其表征

天然棉纤维经超声波预处理后用纤维素酶解制备出纳米纤维素晶体,用LS、TEM、FITR、XRD等进行表征,结果表明所制备的纳米纤维素晶体平均粒径约6 nm,大部分为球状粒子,有少量棒状一维纳米纤维素存在,样品具有良好的单分散性,NCC的聚合度降低,但保持着天然纤维素的基本化学结构。     

A Review on Nanocellulose and Its Application in Supercapacitors

Commercially available supercapacitors offer very limited advantages over other energy storage devices. Balancing their electrochemical performance such as capacitance, energy density, and cyclability is challenging. Studies have shown that this challenge can be overcome by using light and cheap substrates that are highly stable with solvents, and have high loading capacities and compatibility with nanomaterials. Nanocellulose, derived from wastes or biomass, is a good candidate for integrating with other nanosize conductive materials, such as carbon, conducting polymers, and metal oxides, as active materials or nanocomposites for supercapacitors. This review focuses on the properties and preparation of nanocellulose sourced from wastes (biomass) and bacteria, and extends to emerging materials, such as metal–organic frameworks and MXene, for nanocellulose-based supercapacitors. Even though supercapacitors are mainly composed of electrodes, electrolytes, and separators, this paper focuses on the overall electrochemical performance of nanocellulose-based supercapacitors to evaluate the influence of nanocellulose. In addition, the potentials and possible limitations of nanocellulose in supercapacitors are discussed. Overall, the incorporation of waste-derived nanocellulose into energy storage applications is an initiative that improves the circular economy and supports environmental sustainability.     

Nanocellulose water treatment membranes and filters: a review

This review covers the use of nanocelluloses in water treatment applications with particular focus on membranes and filters made either entirely from (nano)cellulose or in composite approaches. Nanocelluloses are among the emerging materials of this century, having found an abundance of potential applications in the fields of composites, medicine, functional additives or water treatment. Water treatment applications in particular have received significant academic and commercial attention, with a large variety of approaches developed in order to address arguably one of the largest problems that humanity is confronted with in the 21st century: clean water. In this regard, treatment of both potable water and wastewater is of high importance. The reason for the viability of nanocelluloses as base material relies upon their high specific surface area and abundance of OH groups that already exhibit certain attraction toward pollutants carrying ionic structures or dyes and also can be easily modified to significantly increase the affinity of nanocelluloses toward these pollutants. Nanocelluloses in their various forms (cellulose nanocrystals, cellulose nanofibrils, bacterial cellulose) have been applied in water treatment, with membranes and filters (size exclusion, e.g. for nanoparticle filtration, or affinity membranes) as well as adsorbents (e.g. heavy metal ions, dyes, nitrates) being the most studied. © 2020 The Author. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

硝化细菌纤维素的制备及表征

以细菌纤维素为原料,用硝硫混酸法合成出硝化细菌纤维素(NBC)。结果表明,采用硝硫混酸法合成硝化细菌纤维素未造成细菌纤维素的网状结构明显断裂降解,且合成出的硝化细菌纤维素安定性能达到A级硝化纤维素标准。用差示扫描量热法对产物进行了表征,并计算出硝化细菌纤维素的热分解活化能为212.53kJ/mol,表明硝化细菌纤维素热的稳定性优于硝化棉。     

Use of an in vitro dynamic culture system to assess flow shear forces upon cell adhesion within different structures

The cover image is based on the Research Article Use of an in vitro dynamic culture system to assess flow shear forces upon cell adhesion within different structures by Xingyou Hu et al., DOI: 10.1002/jctb.5834 .

     

具有抗菌性能的新型载银细菌纤维素纳米纤维(英文)

In this work, we describe a novel facile method to prepare long one-dimensional hybrid nanofibers by using hydrated bacterial cellulose nanofibers（BCF） as a template. Silver（Ag） nanoparticles with an average diameter of 1.5 nm were well dispersed on BCF via a simple in situ chemical-reduction between AgNO3 and NaBH4 at a relatively low temperature. A growth mechanism is proposed that Ag nanoparticles are uniformly anchored onto BCF by coordination with BC-containing hydroxyl groups. The bare BCF and as-prepared Ag/BCF hybrid nanofibers were characterized by several techniques including transmission electron microscopy, X-ray diffraction, thermogravimetric analyses, and ultraviolet-visible（UV-Vis） absorption spectra. The antibacterial properties of Ag/BCF hybrid nanofibers against Escherichia coli（E. coli, Gram-negative） and Staphylococcu saureus（S. saureus, Gram-positive） bacteria were evaluated by using modified Kirby Bauer method and colony forming count method. The results show that Ag nanoparticles are well dispersed on BCF surface via in situ chemical-reduction. The Ag/BCF hybrid nanofiber presents strong antibacterial property and thus offers its candidature for use as functional antimicrobial agents.     

Hemocompatible polyurethane/gelatin-heparin nanofibrous scaffolds formed by a bi-layer electrospinning technique as potential artificial blood vessels

In this paper, a scaffold, which mimics the morphology and mechanical properties of a native blood vessel is reported. The scaffold was prepared by sequential bi-layer electrospinning on a rotating mandrel-type collector. The tubular scaffolds (inner diameter 4 mm, length 3 cm) are composed of a polyurethane (PU) fibrous outer-layer and a gelatin-heparin fibrous inner-layer. They were fabricated by electrospinning technology, which enables control of the composition, structure, and mechanical properties of the scaffolds. The microstructure, fiber morphology and mechanical properties of the scaffolds were examined by means of scanning electron microscopy (SEM) and tensile tests. The PU/gelatin-heparin tubular scaffolds have a porous structure. The scaffolds achieved a breaking strength (3.7±0.13 MPa) and an elongation at break (110±8%) that are appropriate for artificial blood vessels. When the scaffolds were immersed in water for 1 h, the breaking strength decreased slightly to 2.2±0.3 MPa, but the elongation at break increased to 145±21%. In platelet adhesion tests the gelatin-heparin fibrous scaffolds showed a significant suppression of platelet adhesion. Heparin was released from the scaffolds at a fairly uniform rate during the period of 2^nd day to 9^th day. The scaffolds are expected to mimic the complex matrix structure of native arteries, and to have good biocompatibility as an artificial blood vessel owing to the heparin release.     

纳米纤维素的应用研究及潜在市场分析

纳米纤维素是一种生物纳米材料,它取之于丰富的可再生资源,具有生物可降解性能,低的环境、健康和安全风险。近来纳米纤维素研究与开发取得了长足进展,其低成本、低密度、优良的物理和力学性能受到业内的注意。简要介绍了纳米纤维素技术状况,应用研究进展及业已十分清晰的潜在市场。     

基于专利的纳米纤维素技术现状与分析

通过智慧芽专利分析系统收集国内外纳米纤维素专利数据,运用定量的专利分析、专利地图聚类及多主路径方法,对纳米纤维素专利公开趋势、专利权人地域分布、主要专利权人、高被引专利、主要技术领域和技术演化路径进行分析。结果表明：纳米纤维素专利技术处于快速发展阶段,是国内外研究的热点;美国、中国、日本、印度、芬兰等国家处于领先地位;我国纳米纤维素专利申请以大学为主,专利数量众多,在世界范围内排名第一,但缺乏高质量、高影响力的专利,影响力有待提高;纳米纤维素的制备方法一直是重点,且应用领域非常广泛。     

肝素/鱼源明胶改性细菌纳米纤维素管用于小口径人工血管的潜力

细菌纳米纤维素(bacterial nano-cellulose, BNC)具有优良的生物相容性和优异的湿态力学性能,已经被用于人工血管领域的研究。在作为小径人工血管上,其抗凝血性能仍有待进一步提高。本研究通过复合鱼源明胶(Gel)制备BNC/Gel复合管以获得更好的生物相容性和力学强度,并为接枝肝素奠定基础。通过EDC/NHS反应体系,在复合管壁上接枝肝素,得到肝素化的复合管(BNC/Gel/Hep)。结果表明接枝肝素的复合管能够抑制血小板的黏附,血浆复钙时间从纯BNC管的3 min上升到12 min。纯BNC管与复合管的溶血率小于1.0%,均可满足小口径人工血管国家标准;而接枝肝素的BNC管和BNC/Gel复合管的溶血率均明显小于纯BNC管。BNC/Gel/Hep复合管比纯BNC管和BNC/Gel更有利于HUVECs的增殖和生长;而BNC/Gel复合管更有利于HSMCs的生长。BNC/Gel/Hep复合管具有良好的血液和细胞相容性,在小径人工血管的应用上潜力更大。