Preconcentration of Vanadium(Ⅴ) on Crosslinked Chitosan and Determination by Graphite Furnace Atomic Absorption Spectrometry

A new method is proposed for the preconcentration of vanadium(Ⅴ) with crosslinked chitosan (CCTS) and determination by graphite furnace atomic absorption spectrometry (GFAAS). The adsorption rate of vanadium(Ⅴ) by CCTS was 97% at pH 4.0, and vanadium(Ⅴ) was eluted from crosslinked chitosan with 2 mL 2.0 mol·L -1 chlorhydric acid and determined by GFAAS. The detection limit (3σ,n=7) for vanadium(Ⅴ) was 4.8×1 0 -12g and the relative standard deviation (R.S.D) at concentration level of 2.6 μg·L -1 is less than 3.6%. The method shows a good selectivity and high sensitivity, and it was applied to determination of vanadium(Ⅴ) in oyster and water samples. The analytic recoveries are (97±5)%.

Preparation and characterization of crosslinked chitosan-based nanofibers

Crosslinked chitosan-based nanofibers were successfully prepared via clectrospinning technique with heat mediated chemical crosslinldng followed. The structure, morphology and mechanical property of nanofibers were characterized by attenuated total reflection-Fourier transform infrared spectroscopy （ATR-FTIR）, scanning electron microscopy （SEM）, Instron rnachine, respectively. The results showed that, nanofibers exhibited a smooth surface and regular morphology, and tensile strength of nanofibers improved with increasing of triethylene glycol dimethacrylate （TEGDMA） content.

A three-dimensional crosslinked chitosan sulfate network binder for high-performance Li-S batteries

Poor cycling performance caused by the shuttle effect of polysulfides is the main obstacle in the development of advanced lithium-sulfur(Li-S)batteries.Functional polymer binders with polar groups can effectively adsorb polysulfides chemically,thereby suppressing the shuttle effect.Herein,a robust three-dimensional crosslinked polymer network,which demonstrates excellent mechanical property and strong affinity for polysulfides,is prepared by the aldimine condensation and coordination reactions.The crosslinked chitosan sulfate network(CCSN)significantly enhances the cycling performance and rate capability of the sulfur cathode.The CCSN-based sulfur cathode exhibits a high initial discharge capacity of 824 m Ah g^(-1) with only 0.082%average capacity loss per cycle at 1 C.At a high rate of 4 C,the cathode exhibits a high capacity retention of 84.8%after 300 cycles.Moreover,the CCSN-based sulfur cathode exhibits an excellent cycling performance at a high sulfur loading of 2.5 mg cm^(-2),which indicates the excellent mechanical strength and binding performance of the CCSN binder for high-energy density Li-S batteries.This study demonstrates a viable approach for developing high-performance Li-S batteries for practical application.

THE PREPARATION OF CROSSLINKED N,O-CARBOXYMETHYL CHITOSAN RESINSAND THEIR ADSORPTION PROPERTIESFOR TRIGLYCERIDE IN SERUM

Crosslinked N, O-carboxymethyl chitosan resins which can selectively adsorb triglyceride, were prepared by the reaction of N, O- carboxymethyl chitosan with glutaraldehyde solution. Adsorption experiments were performed by adding the resins to the serum. The results showed that this type of adsorbent could cut down the concentration of triglyceride in serum by 56. 4% (3. 35mg/gresin ) at most, while concentration of the total protein (TP ) decreased only by 10. 9% at least, so this novel adsorbent can be used to cure hypertriglyceridemia by hemoperfusion in the future.

Evaluation of different crosslinking methods in altering the properties of extrusion-printed chitosan-basedmulti-material hydrogel composites

Three-dimensional printing technologies exhibit tremendous potential in the advancing fields of tissue engineering and regenerative medicine due to the precise spatial control over depositing the biomaterial.Despite their widespread utilization and numerous advantages,the development of suitable novel biomaterials for extrusion-based 3D printing of scaffolds that support cell attachment,proliferation,and vascularization remains a challenge.Multi-material composite hydrogels present incredible potential in this field.Thus,in this work,a multi-material composite hydrogel with a promising formulation of chitosan/gelatin functionalized with egg white was developed,which provides good printability and shape fidelity.In addition,a series of comparative analyses of different crosslinking agents and processes based on tripolyphosphate(TPP),genipin(GP),and glutaraldehyde(GTA)were investigated and compared to select the ideal crosslinking strategy to enhance the physicochemical and biological properties of the fabricated scaffolds.All of the results indicate that the composite hydrogel and the resulting scaffolds utilizing TPP crosslinking have great potential in tissue engineering,especially for supporting neo-vessel growth into the scaffold and promoting angiogenesis within engineered tissues.

Studies of Permeabilities of Metallic Ions Through Crosslinked Chitosan Membranes

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The Complex of Crosslinked Chitosan with 4′-formal Benzo-15-crown-5 and Palladium Used as Catalyst for Asymmetric Hydrogenation of α-phenylethanone

The crosslinked chitosan was grafted by 4＇-formal benzo-15-crown-5 to obtaine crosslinked chitosan with 4＇-formal benzo- 15-crown-5（CCTS-N=CH-B- 15-C-5）. Then it was loaded with palldium chloride to gain the heterogeneous catalyst, which was easily isolated from the reaction system. The influences of the Pd content of the catalyst, solvent, and temperature on asymmetric hydrogenation of a-phenylethanone have been studied. The catalyst has been found to catalyze the hydrogenation ofa-phenylethanone into the chiral alcohol, α-phenyl ethanol under the mild condition. The optical yield of （R）- 1-phenylethanol could be obtained as 97.1% under the following conditions： temperature, 30℃; solvent, ethanol; Pd content, 1.43 mmol/g; substrate concentration, 0.02 g/mL due to the cooperative effect of crown ether and chitosan polymer. The stability of this catalyst was also studied at the same time. This chiral natural crosslinked chitosan-palladium complex catalyst could be reused without appreciable change in optical catalytic activity, which will be useful for designing crosslinked-chitosan-based adsorption for metal ions for asymmetric hydrogenation.

THE EFFECT OF MEDIUM ON ADSORPTION OF FREE ACID BY CROSSLINKED CHITOSAN RESIN

The adsorption of free acid of low concentration by crosslinked chitosan resin was followed by electrochemical experimental technique. The effect of acid concentration and the media on adsorption was discussed. The experimental results show that both the apparent rate constant and the interaction energy between the adsorbent and adsorbate are decreased while the concentration of hydrochloric acid is increased. In the adsorption system, the adsorption was effected by addition of organic solvent.

一种壳聚糖改性产物的制备工艺及其产品吸附性能的研究

以壳聚糖(CTS)为母体,加入冰醋酸溶解得到CTS溶液,以无水乙醇为致孔剂,制备多孔壳聚糖微球,将制得的CTS微球与环氧氯丙烷(ECH)交联,制备出羟丙基壳聚糖微球(HPCTS),对产物进行红外光谱和电镜扫描性能表征。通过红外光谱图分析可以看出,ECH与CTS进行了交联反应。比较CTS和HPCTS的电镜扫描图片,发现HPCTS表面因为交联反应而形成大量多孔结构,增加了大量可供吸附重金属离子的空穴,使得HPCTS比交联前的表面积有了大幅提高。通过单因素实验,研究了制备HPCTS的工艺参数,在较优工艺参数下制备的产物交联度可达75.23%,产品具有良好的可再生性。

3D打印壳聚糖水凝胶的设计制备及其在生物医学中的应用

壳聚糖水凝胶具有良好的生物相容性和生物降解性能,被广泛的应用于生物医学领域。壳聚糖水凝胶通常是壳聚糖溶液通过凝胶化过程形成交联结构。具有复杂结构的壳聚糖水凝胶不能通过传统方式制备,进而限制了它在生物医学中的应用。3D打印技术是一种先进的制造技术,可以通过设计模型和调整打印参数制备具有个性化的水凝胶支架和具有高度复杂几何结构的水凝胶,这种水凝胶可以负载细胞和药物,以加速组织再生。壳聚糖水凝胶与3D打印结合在生物医学领域具有广阔的前景。综述了3D打印壳聚糖水凝胶的最新研究进展,根据交联策略的不同,从物理交联壳聚糖水凝胶和化学交联壳聚糖水凝胶两个方向分析了壳聚糖水凝胶的形成机理,讨论了常用的3D打印技术原理,包括喷墨式3D打印、挤出式3D打印以及光固化3D打印(立体光固化成型和投影式光固化成型),介绍了3D打印壳聚糖水凝胶在皮肤伤口愈合、骨组织工程、神经组织工程和药物递送系统中的应用,并对3D打印壳聚糖水凝胶在生物医学中的应用进行展望。

胶原-壳聚糖微球的制备与载药性能研究

本文采用胶原与壳聚糖作为原材料,利用壳聚糖的pH响应性,制备了一种无添加交联剂的复合微球,并通过天狼星红染色法和羟脯氨酸分析法,测定复合微球中胶原的含量。此外,对微球的形貌、粒径、热稳定性以及持水性能进行了系统性分析。通过将姜黄素作为模拟药物,对微球的载药性能进行了探索。

负载小鼠脐带间充质干细胞壳聚糖双胍盐酸盐水凝胶的制备与表征

背景:随着水凝胶材料研究的深入,水凝胶的适用领域也逐渐拓宽,搭载干细胞进行疾病治疗成为研究的一个新方向,但如何构建适宜干细胞生长的水凝胶材料,是目前需要解决的关键问题。目的:探究壳聚糖-壳聚糖双胍盐酸盐-胶原蛋白复合水凝胶的理化性能并评价其负载小鼠脐带间充质干细胞的能力。方法:以壳聚糖、壳聚糖双胍盐酸盐和胶原蛋白为原料,加入交联剂β-甘油磷酸钠和碳酸氢钠物理交联制备水凝胶,根据成胶时间和成胶效果筛选出合适的水凝胶(以此记为Gel-1、Gel-2、Gel-3)。表征3组水凝胶电子显微镜下的形态、孔隙率、溶胀性能、降解性,并进行溶血实验考查3组水凝胶的溶血情况。将小鼠脐带间充质干细胞与表征综合性能最好的水凝胶共培养,测定复合水凝胶的细胞毒性、细胞存活情况、细胞黏附效应,从而评价该水凝胶负载脐带间充质干细胞的性能。结果与结论:①扫描电镜表征结果显示,3组水凝胶内部均呈多孔网状结构,添加了壳聚糖双胍盐酸盐的Gel-2、Gel-3内部结构更加多孔且立体;②Gel-3组水凝胶孔隙率高于其余两组,孔隙率高且孔径分布均匀;③3组水凝胶溶胀性能都在100%以上,且具有壳聚糖双胍盐酸盐组分的水凝胶溶胀性能更好;④3组水凝胶的降解率在15 d的时间尺度内可以降解90%以上,降解性能良好;⑤溶血性能测定结果表明各组水凝胶搭载鸡红细胞所测得的吸光度值与生理盐水搭载鸡红细胞所测得的吸光度值基本相同,无溶血现象出现;⑥毒性实验和活死细胞染色实验显示各组水凝胶中细胞存活率都在100%以上,表明无明显细胞毒性,脐带间充质干细胞可在水凝胶包裹下生存且水凝胶对细胞存活率有正向的影响;⑦脐带间充质干细胞可以黏附在水凝胶表面且形态正常。

壳聚糖基自交联粘结剂的合成及其在硅碳负极中的研究

首先以壳聚糖为起始原料,通过羧甲基化处理,显著提升了其水溶性。随后,利用LiOH进行预锂化,并引入双丙酮丙烯酰胺(DAAM)和乙二酸二酰肼(ADH),成功制备了具有出色自交联性能的粘结剂CDD-Li^(+)。为了探究这一粘结剂的结构特性,采用了傅里叶变换红外光谱(FT-IR)技术进行了表征。在粘附性方面,通过180°剥离实验,验证了CDD-Li^(+)的强粘附能力。利用电化学工作站对电池进行了循环伏安曲线的测试。结果显示,CDD-Li^(+)粘结剂所制备的电池能够发生高效的电化学反应,展现出卓越的电化学性能。与常用的聚丙烯酸(PAA)粘结剂相比,CDD-Li^(+)粘结剂在电化学性能上表现更为出色,展现出其在电池领域上的巨大潜力。通过蓝电电池测试仪,进一步研究了电池的倍率性能、循环性能以及锂离子扩散系数,并计算了电池的首圈库伦效率(ICE)。结果显示,CDD-Li^(+)粘结剂制备的电池不仅拥有更优的倍率性能和循环性能,其锂离子扩散系数平均高达10-10数量级,ICE也高达95%。与PAA粘结剂相比,CDD-Li^(+)粘结剂在硅碳负极中展现出更优秀的性能。

壳寡糖交联明胶可生物降解薄膜的制备与性能研究

目的:研究壳寡糖改性对明胶基薄膜性能的影响。方法:以废猪皮中提取明胶为基质,以壳寡糖和聚乙烯醇为改性交联剂,制备得到了明胶基薄膜。利用红外光谱、X射线衍射、扫描电子显微镜、分光光度法、拉力试验测试法对其结构和力学性能进行了测定,并测试了明胶基薄膜在抗氧化、抗菌、水稳定性和生物降解方面的性能。结果:交联改性后明胶薄膜的力学性能得到显著提升,断裂应力最高可达37.09 MPa,最大撕裂能为56.71 kJ/m^(2),且浸泡于水中48 h仍能维持良好的物理形态,此外,薄膜还拥有优异透光性(最大可达92.32%),良好抗氧化性(自由基的清除率最高可达75.12%),优异抗菌性和生物降解性(完全降解时间<45 h)。结论:壳寡糖改性一定程度上改善了明胶基薄膜的力学性能和生物降解性能,赋予了薄膜良好抗菌性和抗氧化能力,表明其在食品包装上存在较大潜在应用价值。

Ni^(2+)印迹磁性交联壳聚糖微球的选择性吸附性能

以Ni^(2+)为模板离子、壳聚糖为主要原料、Fe_(3)O_(4)为磁核、环氧氯丙烷为交联剂,制备了Ni^(2+)印迹磁性交联壳聚糖微球。表征结果显示,微球呈现立体结构,表面有较多褶皱,结晶度降低,有利于对Ni^(2+)的吸附。二元金属离子体系的选择性吸附结果表明,等浓度和不同浓度的Ni^(2+)-Cu^(2+)、Ni^(2+)-Zn^(2+)、Ni^(2+)-Cr^(2+)混合溶液中,微球对Ni^(2+)均有较好的选择性吸附性能,随着Ni^(2+)浓度的增加选择吸附系数增大。Ni^(2+)-Zn^(2+)-Cu^(2+)-Cr^(2+)四元金属离子体系的选择性吸附结果表明,微球对Ni^(2+)的平衡吸附量明显大于其他3种金属离子,平衡吸附量的大小顺序为Ni^(2+)>Cu^(2+)>Zn^(2+)>Cr^(2+),Ni^(2+)相对于Cu^(2+)、Zn^(2+)和Cr^(2+)的选择吸附系数分别为81.545、156.529和544.720。

壳聚糖/玉米淀粉交联膜的制备及性能研究

以壳聚糖(CS)和玉米淀粉(St)为原料、柠檬酸(CA)为交联剂,采用流延法制备了CS/St/CA交联膜。研究了CS与St的质量比以及CA的含量对CS/St/CA膜热稳定性、水溶性、阻湿性以及力学性能的影响。结果表明,CA的加入对CS/St膜的性能有明显影响,且当CS/St的质量比为2/1,CA在溶液中的质量分数为2%时,所制备的CS/St/CA交联膜的综合性能最优。此时,薄膜的最大热分解温度为366.3℃,质量保留率为28.29%,含水量为8.16%,水溶性为28.48%,溶胀度为18.72%,薄膜表面的水接触角为101.5°,薄膜的水蒸气透过量为8 g/(m^(2)·24 h),降低了12.25倍,水蒸气透过系数为0.488×10^(-13)g•cm/(cm^(2)·s·Pa),拉伸强度从3.7 MPa提高到了12.5 MPa,断裂伸长率从85.3%提高到了113.2%。

ELECTROSPINNING OF ZEIN/CHITOSAN COMPOSITE FIBROUS MEMBRANES

Zein/chitosan composite fibrous membranes were fabricated from aqueous ethanol solutions by electrospinning. Poly（vinyl pyrrolidone） （PVP） was introduced to facilitate the electrospinning process of zein/chitosan composites. The asspun zein/chitosan/PVP composite fibrous membranes were characterized by scanning electron microscopy （SEM） and tensile tests. SEM images indicated that increasing zein and PVP concentrations led to an increase in average diameters of the composite fibers. In order to improve stability in wet stage and mechanical properties, the composite fibrous membranes were crosslinked by hexamethylene diisocyanate （HDI）. The crosslinked composite fibrous membranes showed slight morphological change after immersion in water for 24 h. Mechanical tests revealed that tensile strength and elongation at break of the composite fibrous membranes were increased after crosslinking, whereas Young＇s modulus was decreased.

Chitosan Sub-micron Particles Prepared Using Sulfate Ion Salt as Bacteriostatic Materials in Neutral pH Condition

In this paper, the newly developed ion exchange phase separation method to create chitosan sub-micron particles is introduced: 1) chitosan was dissolved in a lactic acid aqueous solution. 2) the obtained chitosan solution was added stepwise in a sodium sulfate aqueous solution and cooled down to 5℃ to become slightly turbid through agglutination. 3) desalinating and deacidifying of the mixture was carried out by a dialyzing tube method. IR spectroscopy and elemental analysis indicated that the agglutination of chitosan was induced by crosslinking effect with an electrostatic interaction between sulfate anions and amino groups in the glucosamine unit although large excess of Na2SO4 caused undesirable further agglutination of the resultant chitosan particles. As a result, the proper amount of Na2SO4 was approximately 1.0 - 10.0 equivalent for the amino group to create the chitosan particles with a sub-micron size. In addition, we investigated an antibacterial activity test for Escherichia coli of the obtained chitosan particles. The significant antibacterial activity was observed in incubation even at neutral pH condition while the chitosan microbeads (size: ca 200 ∫m) prepared by the conventional method and chitosan granules (size: ca 600 ∫m) as starting materials showed almost no antibacterial activity in the same condition.

Preparation and Characterization of Chitosan Microsphere Loading Bovine Serum Albumin

To optimize the preparation process of chitosan microspheres and study its loading capacity, chitosan microsphere was prepared by crosslinking with glutaraldehyde, and bovine serum albumin （BSA） was absorbed onto chitosan microsphere. Scanning electron microscope （SEM）, Fourier transform infrared spectroscopy （FITR）, TA instruments and zeta potentiometer analyzer were used to characterize the parameters with respect to size, thermal characters, morphology, and zeta potential of the microspheres. The loading capability and in vitro release tests were carried out. The results showed that chitosan microsphere with particle size less than 10 μm and positively charged （＋25.97±0.56 mV） can be obtained under the aldehyde group to amino group ratio at 1：1. A loading capacity of BSA at 28.63±0.15 g/100 g with corresponding loading efficiency at 72.01±1.44% was obtained for chitosan microsphere. In vitro test revealed a burst release followed by sustained-release profile.