纳米纤维素研究及应用进展Ⅰ

纳米纤维素是一种新型的高分子功能材料,具有独特的结构和优良的性能。特别是细菌纤维素,其三维纳米网状结构,生物适应性,良好的机械稳定性,抗菌性等优良性能使它越来越收到重视。本文介绍了近年来对于纳米纤维素制备和应用的研究进展,主要涉及细菌纤维素,植物纤维素和纤维素纳米复合物的制备。本文的下篇《纳米纤维素研究及应用进展Ⅱ》将继续介绍纳米纤维素在生物,医学,增强剂,造纸工业,净化,传导,与无机物复合,食品工业,磁性复合物等方面的应用。     

纤维素纳米晶体的制备及其在复合材料中的应用

纤维素纳米晶体是纤维素原料经加工而得到的纳米级棒状或球状晶体。由于其具有高强度、大比表面积、生物相容性、可再生性和可降解性等优良性能,可应用于复合材料、生物医药和环境等多个领域。本文详细综述了近年来制备纤维素纳米晶体的常用方法,包括酸水解法、氧化法、酶水解法、机械法、溶剂法以及组合法。同时,讨论了各种制备方法的优缺点。在应用研究方面,本文总结了其在增强复合材料、膜过滤复合材料、导电复合材料和无机纳米复合材料等热门领域的研究情况。最后,对纤维素纳米晶体的未来发展方向进行了展望。     

纳米材料对PHBV增韧改性的研究进展

聚(β-羟基丁酸酯-β-羟基戊酸酯)(PHBV)是一种拥有生物可降解性、生物相容性、压电性、光学活性等诸多优良特性的热塑性树脂,具有广阔的应用前景。但是PHBV脆性大,韧性差,导致其应用受到限制。本文综述了近年来国内外纳米材料增韧改性PHBV的进展。当纳米材料添加到PHBV时,可以起到异相成核剂的作用,改善结晶性能,从而降低PHBV的脆性。在众多的纳米材料中,纳米纤维素质量轻、强度高、模量大并可生物降解,有希望在不影响PHBV自身降解性的基础上提高其韧性。文章最后概括了目前纳米纤维素增韧PHBV存在的几点问题,同时对用纳米纤维素增韧PHBV的发展前景提出展望。     

微纤化纤维素的制备及应用

微纤化纤维素（MFC）是一种新型的纳米级功能材料,由于其具有生物相容性、生物可降解性、优良的力学性能、光学性能以及阻隔性能,在纳米纸、气凝胶、复合材料、造纸、医药等诸多领域具有广阔的应用前景。但MFC在制备及应用过程中还存在诸多问题,例如机械处理能耗高,无法工业化生产;MFC极性强,在非极性基质中分散不均,这些都限制了其在纳米复合材料领域的发展,因此需要通过预处理降低机械处理过程中的能耗,同时系统地对MFC与聚合物复合机理进行研究以拓宽MFC的应用领域。本文综述了MFC的制备方法及其在纳米纸、气凝胶及纳米复合材料方面的应用现状,并对MFC的未来发展方向进行了展望。     

纳米金生物探针及其应用

纳米技术与生物技术的融合,使纳米生物技术获得了很多重要的进展.纳米金作为研究较早的一种纳米材料,其在纳米生物探针方面的应用是最近几年较为活跃的研究方向.本文评述了近年来纳米金探针在生物分析中的应用及进展,阐述了纳米金与生物大分子作用的机理,介绍了纳米金探针在核酸分析、免疫分析、单细胞分析和靶向药物载体4个方面应用的最新进展,并对其未来的发展方向进行了展望.     

纳米纤维素的制备*

在纳米尺寸范围操控纤维素分子及其超分子聚集体,结构设计并组装出稳定的多重花样,由此创制出具有优异功能的新纳米精细化工品、新纳米材料,是纤维素科学的前沿领域和热点。为了研究当前制备纳米纤维素的现状和发展方向,简述了纳米纤维素化学基础,介绍了三类纳米纤维素：纳米纤维素晶体（晶须）、纳米纤维素复合物和纳米纤维素纤维,重点综述了纳米纤维素的五种制备方法：化学法制备纳米纤维素晶体和晶须、生物法制备细菌纤维素、物理法制备微纤化纳米纤维素、人工合成纳米纤维素和静电纺丝制备纤维素纤维,讨论了各种制备方法的优点和缺点,指出开展纳米纤维素超分子的可控结构设计、立体与位向选择性控制与制备、分子识别与位点识别等自组装过程机理、多尺度结构效应的形成机理等基础理论性研究是主要研究基础,新型的、绿色、低能耗、快速、高效的制备方法是纳米纤维素制备方法的发展方向。     

聚苯胺纳米复合材料的优良性能

聚苯胺纳米复合材料因结合了聚苯胺和纳米粒子的特殊性能,从而改善了基体的物理化学性能,赋予了材料前所未有的独特的性能,成为目前研究最为广泛的导电高分子纳米复合材料之一.本文基于国内外最新研究文献,结合典型事列详细综述了聚苯胺纳米复合材料在生物传感、催化、电磁、微波吸收和光电等方面呈现出的独特性能,简单评述了其在生物传感、催化、电磁、微波吸收、防腐等领域的应用前景.     

介质和力场协同作用对纳米纤维素形貌结构的调控

纤维素是一种由直链多聚糖通过糖苷键连接而成的巨型线性高分子,纤维素分子链通过氢键紧密排列形成纤维素晶体.由于纤维素晶体具有优良的化学可修饰性和机械性能等优点,纳米化加工的纤维素可广泛应用于日常生活和工业生产的各个领域.本文主要介绍了本课题组在机械剪切力作用下,实现纤维素纳米化并同时进行亲水或疏水改性的研究进展,重点介绍了介质极性对纤维素分子链之间相互作用的影响,并通过改变分子链之间的相互作用来调控纳米化纤维素的形貌和亲、疏水性.提出机械外力和环境极性协同作用下,晶面导向剥离纤维素的理论.     

纳米载体固定化酶的最新研究进展

催化剂是化学工业的重要基础,其中酶是重要的高效天然催化剂。近年来,酶被越来越多地应用于工业领域,如精细化工、食品工业、制药工业、纺织业和制浆造纸。然而,由于游离酶存在价格昂贵及操作稳定性(特别是回收与重复使用性能)低等缺点,其在工业上的进一步应用受到一定限制。对酶进行固定化是解决上述问题的有效途径。一个理想的酶固定化技术需要载体具有良好的生物相容性和高比表面积,能够负载适量的酶并且具有很好的重复使用性能,固定化酶的过程简单温和,所得到的固定化酶制剂具有良好的催化性能、稳定性以及工业应用价值。尽管固定化酶技术经过了多年的发展,但仍需进一步研究。近几年,人们研究了基于纤维素纳米晶类、聚多巴胺类纳米载体以及生物相容性合成有机物纳米胶等新型载体对酶的固定化,取得了较好的成果。本文综述了这些新型纳米载体的制备以及酶的固定化过程,阐述了纳米载体固定化酶的结构和催化性能,并展望了发展前景。纤维素是全球产量最高、来源最广的生物聚合物。纤维素经过一定的酸(常用硫酸和盐酸)水解处理后,剩下的是具有高结晶度的纤维素纳米晶。它具有高比表面积、高机械强度和高长径比等优异性能。因此,研究者利用纤维素纳米晶作为载体进行酶固定化,获得了高负载量、高催化性能的固定化酶制剂。基于仿生矿化法制备的聚多巴胺类材料近年来获得研究者越来越多的关注。多巴胺具有良好的自聚合能力,可以对无机、有机等各种材料进行表面修饰。同时,聚多巴胺中含有的活性官能团可以与酶发生交联,从而达到固定化酶的效果。基于合成性聚合物纳米胶载体的固定化酶技术同样是一个新兴的、有意义的研究领域。相关的固定化过程可分为两大类：(1)在酶分子表面通过原位聚合生成纳米胶(growing-from过程);(2)将酶与预先合成的纳米胶进行交联(grafting-to过程)。其中, growing-from过程是先将酶分子丙烯酰化,再进行原位聚合。而原位聚合又可分为自由基聚合、原子转移自由基聚合(ATRP)和可逆加成-断裂链转移聚合(RAFT)。其中, ATRP和 RAFT主要用于制备环境响应型的酶-聚合物纳米凝胶。     

纳米孔分析化学

源于自然界,服务于人类社会的纳米尺度装置包括生物及人工制备的纳米孔与纳米通道等。基于这些纳米尺度装置的分析化学简称纳米孔分析化学。本文对纳米孔分析化学的发展,特别是近年来在DNA测序、蛋白质分析的进展进行了综述,对于纳米孔分析化学发展的历史、基本分类、原理和应用作了介绍与展望。     

Nanocellulose: a promising nanomaterial for fabricating fluorescent composites

Cellulose - Nanocellulose (NC) is a new biomass nanomaterial with at least one dimension in the nanoscale, prepared from plant fibers, animal, and bacteria. Nanocellulose combines important...     

Growth factor functionalized biodegradable nanocellulose scaffolds for potential wound healing application

Cellulose - Nanocellulose has been highlighted as one of the most promising biomaterials for biomedical applications with the potential to outperform conventional polymeric materials. However, the...     

Filler-nanocellulose substrate for printed electronics: experiments and model approach to structure and conductivity

Composites made of inorganic filler particles and cellulose nanofibres can be applied as substrates for printed electronics. We have studied the structural properties of these substrates both experimentally and with particle-level modeling approach. Our model describes the skeleton structure formed by pigment particles of varied shapes and size distributions. Nanocellulose is assumed to fill voids of the structure. The model simulations predict quite well the relative changes in measured density, porosity and roughness for kaolin and precipitated calcium carbonate (PCC) pigments. Measured roughness turns out to be higher for kaolin than for PCC. Yet, the measured conductivity of printed lines on kaolin surface is higher than the conductivity on the PCC surface. The simulations reveal a more open surface pore structure for PCC than for kaolin, which leads to stronger absorption of the silver ink, and thus explains the differences in the measured conductivities.     

Cellulose nanoanemone: an asymmetric form of nanocellulose

Cellulose - Nanocellulose with increasing attention in basic research and for use in advanced materials is usually considered to have a symmetrical nanofibril, nanorod or fibrillated nanofiber...     

Comparative study on properties of nanocellulose derived from sustainable biomass resources

Cellulose - Nanocellulose, a unique and promising nanosized cellulose fibers extracted from renewable biomass, has gained much attention from both the scientific and industrial communities due to...     

Enhanced curcumin loaded nanocellulose: a possible inhalable nanotherapeutic to treat COVID-19

Cellulose - Nanocellulose/polyvinyl alcohol/curcumin (CNC/PVA/curcumin) nanoparticles with enhanced drug loading properties were developed by the dispersion of nanocellulose in curcumin/polyvinyl...     

Nanocellulose characteristics from the inner and outer layer of banana pseudo-stem prepared by TEMPO-mediated oxidation

Many tonnes of agricultural wastes are generated annually, which contains a relatively high amount of cellulose; banana pseudo-stem is one waste type that is a promising material for nanocellulose production. This research characterised nanocellulose from inner and outer layers of banana pseudo-stem as a preliminary research strategy for designing biodegradable packaging material from banana pseudo-stem nanocellulose. Nanocellulose was successfully prepared through TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl)-mediated oxidation. The extracted nanocellulose from both the inner and outer layers had observed widths of approximately 7–35 nm and long fibrillated fibre. They had high negative zeta potential (lower than ?33.6) that provided good colloidal stability. The purity of the nanocellulose was high as demonstrated by ¹³C solid-state NMR and Fourier transform infrared spectroscopy. Nanocellulose from both layers was significantly more crystalline than the raw materials. Thermal stability of nanocellulose sourced from inner and outer layers was relatively similar, with degradation temperature of approximately 220 °C, which was slightly lower than the degradation temperature of its native form (232 °C for inner layer and 261 °C for outer layer).     

Nanocellulose as a novel nanostructured adsorbent for environmental remediation: a review

Nanocellulose is a lightweight material with strong mechanical strength, inexpensive production costs and safe handling compared to synthetic nanoparticles. Thanks to the high specific surface area, broad possibility of surface modification and high mechanical strength, nanocellulose has emerged as a new class of biobased adsorbent with promising potential application in environmental remediation. Many classes of pollutants could be adsorbed by nanocellulose, including heavy metals, dissolved organic pollutants, dyes, oil and undesired effluents. The possibility for the regeneration of the nanocellulose adsorbent is another benefit driving attempts to fully exploit this new class of nanostructured biobased material. In this review, an update of the most relevant uses of nanocellulose as a new class of adsorbents for environmental remediation is outlined. An emphasis on the key advancement of surface modifications of nanocellulose to enhance the adsorption efficiency according to the pollutant class is highlighted.     

Carboxyl-functionalized Nanocellulose Reinforced Nanocomposite Proton Exchange Membrane

Nanocellulose(NCC) was prepared through the acid hydrolysis of microcellulose(MCC) and was reacted with maleic anliydride to obtain carboxyl-functionized nanocellulose(MA-NCCs). The presence of .OH and .SO3H on the surface of rod-like MA-NCC was confirmed by Fourier transfonn infrared spectrometry(FTIR). Sulfonated poly(aryl ether ether ketone ketone)(Ph-SPEEKK) was synthesized with bis(4-fluorophenyl-methanone) and 2-phenylhydroquinone as monomer. MA-NCC/Ph-SPEEKK nanocomposite membranes with different MA-NCCs content were prepared, and their properties were characterized. Compared with Ph-SPEEKK, MA-NCC/Ph-SPEEKK nanocomposite membrane showed better mechanical and thermal properties and higher proton conductivity. The proton conductivity of the composite membrane with 4%(mass fraction) MA-NCCs under 80℃ was 0.095 S/cm. And its tensile strength reached 30.3 MPa, which was 21.2% higher than that of Ph-SPEEKK pure polymer membrane.