In vivo behavior of carboxymethylcellulose based microgels containing 67Cu

Using a mouse model, an organ distribution for microgels of carboxymethyl cellulose cross-linked with ⁶⁷Cu²⁺ ions was investigated and compared with the distribution of free ⁶⁷Cu²⁺ ions from ⁶⁷CuCl₂. The clearance of the microgels through both liver and kidneys was demonstrated. An additional examination of distribution for [³H]CMC microparticles and [³H]CMC–Cu microgels revealed no copper release from the microgels in vivo.     

Fabrication of Translucid Gold-Nanocellulose Electrodes and their Potential Application as Hydrogen Peroxide Sensor

In this work, we describe the fabrication of a transparent gold electrode based on nanocellulose. The electrode was prepared via electron beam evaporation of gold onto nanocellulose films previously spread over a glass slip. Electrodes with different thickness of Au was fabricated, and the material's optical, morphological and electrical properties were assessed. Finally, as a proof of concept, a possible application of this electrode in hydrogen peroxide sensing was performed. The results show that a thin layer of gold on a nanocellulose translucid film allows obtaining a conductive transparent surface that could be used to design a transparent electrode.     

Thermal Properties of Carboxymethylcellulose and Methyl Methacrylate Graft Copolymers

Carboxymethyl cellulose and methyl methacrylate graft copolymers (CMC-g-PMMA) were synthesized by using potassium persulphate (KPS) as initiator. These graft copolymers were characterized by Fourier transform infrared spectra (FTIR), thermogravimetric analyses (TGA), and differential scanning calorimeter analyses (DSC). In addition, the nonisothermal thermal decomposition kinetics of copolymers was studied. The experimental results indicated that in the temperature range from 300°C to 450°C, the copolymer had a mass loss. The activation energy was 41.96 kJ/mol, and the logarithm of the Arrhenius coefficient (lnA) was 17.31.     

In Situ Crystallization of Bacterial Cellulose III. Influences of Different Polymeric Additives on the Formation of Microfibrils as Revealed by Transmission Electron Microscopy

Effects of polymer additives on the formation of microfibrils of bacterial cellulose have been examined by transmission electron microscopy. Among additives with different degrees of polymerization (DP) or substitution (DS), carboxymethyl cellulose sodium salt (CMC) with DP = 80 and DS = 0.57 is the most effective in producing separate, smaller-size microfibrils. By increasing the concentration of this CMC from 0.1 to 1.5%, the percentage of microfibrils measuring 3–7 nm wide is increased and levels off at around 1.0%. Other polymer additives such as xyloglucan are less effective than CMC in producing microfibrils with smaller sizes and the resulting microfibrils still tend to aggregate. The number of charged substituents and the molecular weight seem to be important factors in the production of highly separate smaller-size microfibrils. The reduction in average microfibril size is well correlated to the decrease in mass fraction of cellulose I in bacterial cellulose crystals. On the basis of these results, the mechanism of the crystallization of celluloses I and I is discussed. The effect of colony types, smooth and rough, on the formation of microfibrils in the presence of CMC is also described.     

Carboxymethyl poly(L‐histidine) as a new pH‐sensitive polypeptide at endosomal/lysosomal pH

A carboxymethyl poly(L ‐histidine) has been synthesized as a new pH‐sensitive polypeptide at endosomal/lysosomal pH. Because of its poor water solubility at physiological pH, an application of poly(L ‐histidine) with a pK_a around 6.0 has been limited in spite of the native possession of the pH‐dependent property change at endosomal pH. Although the unmodified poly(L ‐histidine) suddenly precipitates out of the aqueous medium above pH 6.0 as the result of the deprotonation of the imidazole groups, the water solubility of the resulting carboxymethyl poly(L ‐histidine) has been improved at physiological pH. A solution turbidity measurement proved that no significant effect on a rapid aggregate formation or phase separation of serum proteins is induced by carboxymethyl poly(L ‐histidine). Hemolysis assay showed that the carboxymethyl poly(L ‐histidine) enhances membrane disruptive ability at endosomal/lysosomal pH. The cellular uptake of luciferase in the presence of the carboxymethyl poly(L ‐histidine) increases intracellular luciferase activity, which suggests that the carboxymethyl poly(L ‐histidine) makes the luciferase escape from lysosomal degradation. The carboxymethyl poly(L ‐histidine) would be the fundamental compound for designing various drug carriers with the pH sensitivity at endosomal/lysosomal pH. Copyright © 2007 John Wiley & Sons, Ltd.     

Recent advancement and development of chitin and chitosan-based nanocomposite for drug delivery: Critical approach to clinical research

This review depicts the exposure of chitin and chitosan base multifunctional nanomaterial composites for promising applications in field of biomedical science structure, synthesis as well as potential application from a colossal angle. We elaborated critically each of the chitin and chitosan base nanomaterial with its potential application toward biomedical science. For different biomedical applications it use in form of hydrogels, microsphere, nanoparticles, aerogels, microsphere and in form of scaffold. Due to this it had been blended with different polymer such as starch, cellulose, alginate, lipid, hyaluronic acid, polyvinyl alcohol and caboxymethyl cellulose. In this review article, a comprehensive overview of combination of chitin and chitosan base nanomaterial with natural as well as synthetic polymers and their biomedical applications in biomedical field involving drug delivery system all the technical scientific issues have been addressed; highlighting the recent advancements.     

A New Approach in the Analysis of the Substituent Distribution of Carboxymethyl Celluloses

An approach is presented for the quantitative analysis of the substituent distribution in carboxymethyl cellulose (CMC). Standard substances have been isolated by preparative HPLC and characterised by ¹³C-NMR spectroscopy. The availability of these reference substances enabled a quantitative HPLC determination of glucose and its seven carboxymethyl derivatives by anion exchange chromatography and pulsed amperometric detection. A comparison of sulphuric acid and perchloric acid hydrolysis for conventional CMC samples gave higher yields for perchloric acid. The yield of the eight CMC building units decreased with increasing DS for both hydrolysis methods. Results were different, when samples from new synthesis concepts were investigated. While CMCs from induced phase separation showed increasing hydrolysis yields up to a DS of 1.9 regioselectively substituted 2,3-O-CMC gave lower yields with increasing DS. For 2,3-O-CMC samples sulphuric acid proved to be the superior hydrolysis medium.     

Preparation and Characterization of Glass Ionomer Cements with Added Carboxymethyl Chitosan

Abstract

Because of their low fracture strength, glass ionomer cements (GICs) can not be applied to the high stress loading areas in dentistry. With the aim to improve the fracture properties of GICs, carboxymethyl chitosan (CMCS) was dissolved in the liquid part of a commercial GIC, Fuji IX, and then mixed with inorganic particles to prepare GICs containing CMCS. The mechanical performance of the GICs containing CMCS showed that the CMCS could enhance the fracture properties of GICs when its concentration in the GICs was in a certain range; 0.0125?wt.% of CMCS in the liquid part of GIC improved both the flexural strength and the fracture toughness. The flexural strength, flexural modulus, and compressive strength results of the GICs containing CMCS after water aging showed that they also had good water aging-resistance.     

羧甲基淀粉的应用与合成

综述了羧甲基淀粉的合成方法、合成过程中的影响因素以及应用现状     

新型含能纤维素基凝胶推进剂的流变性能研究

制备了以羧甲基纤维素硝酸酯(CMCN)为胶凝剂的硝基甲烷(NM)凝胶, 系统研究了CMCN 修饰基团比例变化所引起NM/CMCN凝胶流变性能差异性的规律. 探讨了凝胶的形成机理并采用线性的流变学方法研究了NM/CMCN凝胶的屈服性、触变性、蠕变性、温敏性等动态粘弹性质, 分别利用Herschel-Bulkley 模型、Burger 模型、Carreau-Yasuda模型、Andrade-Eyring 模型对凝胶的流动曲线、蠕变曲线、频率曲线和温敏曲线进行了数据拟合. 研究发现, NM/CMCN凝胶是由CMCN 大分子链上两亲性基团与有机小分子基团间通过分子链间疏水键、氢键等非共价键相互作用形成的一种物理交联网络型凝胶. 凝胶的非牛顿系数n均小于0.60. 随着硝酸酯基团含量的减少, NM/CMCN 凝胶的结构强度变弱, 表现出屈服应力逐渐减小、触变恢复性逐渐增强、粘性与弹性柔量均减小但粘性柔量比例增加的趋势; 凝胶的弹性响应性逐渐减弱而粘性响应性渐强, 内耗也逐渐增大;凝胶的活化能总体上增大, 温度稳定性变弱.