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Polyelectrolyte Complexes between Hyperbranched and Linear Polysaccharides: Fucoidan/Chitosan

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Chinese Journal of Polymer Science 2024年第4期42卷 468-479页

作者： Ekaterina R.Gasilova Daria N.Poshina Aleksandra O.Sitnikova Natalia N.Saprykina Yury A.Skorik institute of Macromolecular Compounds of the Russian Academy of Sciences Bolshoi VO 31St.Petersburg199004Russian Federation

Polyelectrolyte complexes(PECs)of hyperbranched(HB)and linear polysaccharides are promising as more effective encapsulation agents compared to PECs formed by linear *** investigated the PECs between the HB anionic polysaccharide fucoidan(FUC)and the cationic linear polysaccharide chitosan(CS).The FUC had a molecular weight(MW)of 30×*** PECs were prepared in three solvents(water,0.01 and 0.1 mol/L acetic acid)with CS of MW of 15,110 and 170 kDa,and deacetylation degrees(DDA)of 70%and 97%.The structures of the PECs and the initial FUC were investigated by multi-angle static and dynamic light *** the FUC contained 18 wt%of—OSO3 groups and 5 wt%of uronic acid units,it was a“strong-weak”copolyanion,so the HB macromolecules of the FUC formed nanogel particles in 0.1 mol/L AcOH and open branched structures in water,as confirmed by the Kratky *** mixing the solutions of original components,the PEC structures underwent an equilibration period,the duration of which increased with the MW of *** the charge stoichiometry was approached,the PECs shrank;the fractal dimension approached unity,indicating the side-by-side packing of adjacent FUC branches with the help of *** aggregation in the vicinity of the charge compensation was hardly observed,as it occurred in a very narrow *** PEC content at theζ-potential inversion depended on solvents’pH and the DDA of *** the extreme case of core-shell PECs in 0.1 mol/L AcOH,obtained by mixing FUC nanogels with the solutions of high MW CS of 97%DDA,the protruding tails of CS formed a positively charged shell in the whole range of FUC content(10 wt%

关键词： Polyelectrolyte complexes Chitosan Hyperbranched fucoidan Light scattering

Isolation of Thermally Stable Cellulose Nanocrystals from Spent Coffee Grounds via Phosphoric Acid Hydrolysis

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Journal of Renewable Materials 2020年第2期8卷 187-203页

作者： Brody A.Frost E.Johan Foster Virginia Tech Department of Materials Science and EngineeringMacromolecules Innovation Institute117 SurgeVirginia TechBlacksburgVA 24061USA

As the world's population exponentially grows,so does the need for the production of food,with cereal production growing annually from an estimated 1.0 billion to 2.5 billion tons within the last few *** rapid growth in food production results in an ever increasing amount of agricultural wastes,of which already occupies nearly 50%of the total landfill *** example,is the billions of dry tons of cellulose-containing spent coffee grounds disposed in landfills *** paper seeks to provide a method for isolating cellulose nanocrystals(CNCs)from spent coffee grounds,in order to recycle and utilize the cellulosic waste material which would otherwise have no *** have already been shown to have vast applications in the polymer engineering field,mainly utilized for their high strength to weight ratio for reinforcement of polymer-based nanocomposites.A successful method of purifying and hydrolyzing the spent coffee grounds in order to isolate usable CNCs was *** CNCs were then characterized using current techniques to determine important chemical and physical properties.A few crucial properties determined were aspect ratio of 12±3,crystallinity of 74.2%,surface charge density of(48.4±6.2)mM/kg cellulose,and the ability to successfully reinforce a polymer based *** characteristics compare well to other literature data and common commercial sources of CNCs.

关键词： Cellulose nanocrystals phosphoric acid hydrolysis agricultural waste industrial waste spent coffee grounds polymeric nanocomposites renewable cellulosic materials

Nanozyme catalysis in a crowded environment:The impact of diffusion and surface shielding

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Nano Research 2024年第7期17卷 5795-5800页

作者： Vasily G.Panferov Juewen Liu Department of Chemistry Waterloo Institute for NanotechnologyWaterlooOntario N2L 3G1Canada

Nanozymes are widely used in various applications as nanosized catalysts for replacing *** accurate estimation of the catalytic activity of nanozymes in real conditions is *** this article,for the first time,we systematically studied the effect of macromolecular molecules co-existing in the real system on the oxidoreductase(peroxidase,oxidase,and catalase)-mimicking nanozymes made of a gold nanoparticle core and a platinum shell,Prussian Blue,Mn_(2)O_(3) and CoO *** were made with horseradish *** distinguished two main mechanisms of the negative impact of macromolecules on nanozyme catalysis—slowed diffusion and surface shielding of *** the first mechanism is typical for enzymes,the second one is specific only for *** the mechanisms is essential for developing approaches to reduce the unavoidable impact of macromolecules for various analytical and biomedical applications.

关键词： molecular crowding biosensors nanoparticles

Non-isothermal crystallization kinetics of Nylon 10T and Nylon 10T/1010 copolymers:Effect of sebacic acid as a third comonomer

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Chinese Journal of Chemical Engineering 2017年第7期25卷 963-970页

作者： Zhongqiang Wang Guosheng Hu Jingting Zhang Jiusheng Xu Wenbo Shi institute of macromolecules and Bioengineering School of Materials Science and EngineeringNorth University of ChinaTaiyuan 030051China Guongdong SinoplastAdvanced Material Co.Ltd. Dongguon 523860China

Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry(DSC). Jeziorny equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method, respectively. These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10 T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher. The crystal morphology was observed by means of a polarized optical microscope(POM) and X-ray diffraction(XRD). It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10 T, but also significantly increased the number and decreased the size of spherulites. Comparing with the Nylon 10 T, the crystallization rate was increased with the addition of the sebacic acid comonomer.

关键词： Melt polymerization Nylon 10TNylon 10T/1010 Semiaromatic polyamides Crystallization kinetics Non-isothermal crystallization

Gelation Behavior of Poly(Vinylidene Fluoride)-based Gel Polymer Electrolyte

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Journal of Donghua University(English Edition) 2006年第3期23卷 74-78页

作者：王标兵顾利霞 institute of macromolecules and Bioengineering North University of China Taiyuan 030051 College of Materials Science and Engineering Donghua University Shanghai 200051

Poly(vinylidene fluoride) (PVdF)-based gel polymer electrolytes with various compositions were prepared by solution casting technique. The kinetics of gelation was analyzed via the correlation between the apparent gelation rate and concentration of PVdF at a given temperature. Combination the results of the kinetics of gelation and the DSC study, it revealed that the phase separation was the major behavior and the fibrils were the major junction joints of the three-dimensional network even in the case the concentration of PVdF was higher than 25 wt%. The porous surface observed by ESEM also reflected that the phase separation took place during the gelation.

关键词： gel polymer electrolyte phase separation crystallinity morphology.

The 3D organization of genome in the nucleus: from the nucleosome to the 4D nucleome

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Science China(Life Sciences) 2020年第6期63卷 791-794页

作者： Guohong Li National Laboratory of Bio-macromolecules CAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China

The genetic information,stored in the linear sequences of DNA,encodes all of the genes that a living organism uses to produce proteins and RNAs essential for various cellular *** eukaryotes,however,genomic DNA is hierarchically and efficiently packaged into multiple-level chromatin structures within the nucleus,including the nucleosome,30 nm fibers,chromatin loops,topology associated domains(TADs).

关键词： The 3D organization of genome in the nucleus from the nucleosome to the 4D nucleome

A brief account on the study of the insulin crystal structure In retrospect:Forty years after the determination of insulin’s crystal structure by Chinese scientists

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Science China(Life Sciences) 2010年第1期53卷 13-15页

作者： WANG Da-Cheng1 & GU XiaoCheng2 1 National Laboratory of macromolecules,institute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China 2 College of Life Sciences,Peking University,Beijing 100871,China National Laboratory of macromolecules Institute of Biophysics Chinese Academy of Sciences Beijing China College of Life Sciences Peking University Beijing China

"Standards there as high as achieved elsewhere";news delivered to the world by Science in China Approximately forty years ago when China was undergoing a period of great difficulty, Science in China,

关键词： A brief account on the study of the insulin crystal structure In retrospect

Detection of the critical micelle concentration of cationic and anionic surfactants based on aggregation-induced emission property of hexaphenylsilole derivatives

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Science China Chemistry 2009年第6期52卷 755-759页

作者： TANG Li JIN JiaKe ZHANG Shuang MAO Yu SUN JingZhi YUAN WangZhang ZHAO Hui XU HaiPeng QIN AnJun TANG Ben Zhong Department of Polymer Science and Engineering Institute of Biomedical MacromoleculesZhejiang UniversityHangzhou 310027China Department of Chemistry The Hong Kong University of Science&TechnologyHong KongChina

We report a fluorescence "turn-on" method to detect the critical micelle concentration (CMC) of surfactants. This method works well for both cationic and anionic surfactants. It employs an unprecedented mechanism (aggregation-induced emission, or AIE) to determine the CMC values, and the results are consistent with the data obtained by the classical techniques. In addition, this method renders the convenient detection of the CMC values. Any large and professional instruments are unnecessary, instead, a portable UV lamp and an ultrasonic generator are enough to carry out the detection in an ordinary laboratory. Considering that micelles are interesting entities and have found applications in many important fields such as emulsion polymerization, template of nanosized materials synthesis, controllable drug delivery and macromolecular self-assembling. Our experimental results may offer a facile, sensitive and promising method to detect the formation of micelles constructed by the new amphiphilic molecules and macromolecules.

关键词： aggregation-induced emission critical micelle concentration fluorescence probe

Preparation of chitosan rods with excellent mechanical properties: One candidate for bone fracture internal fixation

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Science China Chemistry 2011年第2期54卷 380-384页

作者： WANG ZhengKe HU QiaoLing WANG YouXiang Key Laboratory of Macromolecule Synthesis and Functionalization Ministry of EducationZhejiang UniversityHangzhou 310027China institute of Biomedical macromolecules Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

Chitosan (CS) is one promising material as a temporary mechanical supporter for bone fracture internal *** our previous work,we successfully fabricated CS rods through one in situ precipitation *** bending strength and bending modulus of CS rods need to be improved to match the commercially available devices used for bone fracture internal *** this research,CS rods were reinforced effectively through cross-linking reaction by using glutaraldehyde as the coupling ***’s base was detected by FTIR due to the chemical reaction between amino groups and aldehyde *** plane space of CS rods became small during the formation of network *** was observed by SEM,indicating that layer-by-layer structure became much tighter after cross-linking reaction,and cracks in one layer turned around when they reached another layer to absorb *** strength and bending modulus of cross-linked CS rods could reach 186.3 MPa and 5.17 GPa,*** with uncross-linked CS rods,they are increased by 101.6% and 26.1%,*** a result,mechanical properties of CS rods are equivalent to the commercially available biodegradable *** rods with excellent mechanical properties are a good candidate for bone fracture internal fixation.

关键词： chitosan glutaraldehyde layer-by-layer structure reinforcement biomedical material