A Modified Chitosan Adsorbent for Selective Removal of Low Density Lipoprotein

A modified chitosan adsorbent was synthesized through a simple preparation procedure, and it demonstrated good adsorption performance for selective removal of low density lipoprotein in human plasma. Phase inversion technique was employed to form chitosan beads, to which epoxy groups were then introduced by reacting with ethyleneglycol diglycidylether, and tryptophan was subsequently coupled to the epoxy-activated beads.

Polypyrrole Chitosan Cobalt Ferrite Nanoparticles Composite Layer for Measuring the Low Concentration of Fluorene Using Surface Plasmon Resonance

Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.

Low Releasing Mitomycin C Molecule Encapsulated with Chitosan Nanoparticles for Intravesical Installation

The aim of this investigation is preparation of Mitomycin-C encapsulated with chitosan nanoparticles synthesis using ionic gelation technique for intravesical controlled drug delivery systems. This study was conducted in vitro. Cumulative amount of drug released from the nanoparticles was calculated. Mitomycin-C release studies were examined for different pH values. During the drug loading and release studies, initial amount of drug was changed (i.e., 0.5, 1.25 and 2.5 mg) to get different release profiles and the release studies were repeated (n = 6). The loading efficiencies of Mitomycin-C with three different initial concentrations 0.5mg/ml, 1.25 mg/ml and 2.5 mg/ml into chitosan nanoparticles were 54.5%, 47.1% and 36.4%, respectively. For different pH values, the cumulative releases of Mitomycin-C from chitosan nanoparticles were 47% and 53% for pH 6.0 and 7.4, respectively (p < 0.01). For different drug doses, the cumulative releases of Mitomycin-C (MMC) from Chitosan nanoparticles were 44%, 53% and 65% for 0.5 mg/mL, 1.25 mg/mL and 2.5 mg/mL respectively (p < 0.01). The anticancer activity of Mitomycin-C loaded chitosan nanoparticles was measured in T24 bladder cancer cell line in vitro, and the results revealed that the 2.5 MMC coated Chitosan nanoparticles had better tumor cells decline activity. From this investigation, we conclude that the drug encapsulated synthesized chitosan nanoparticles possess a high ability to be used as pH and dose responsive drug delivery system. This systematic investigation demonstrates a promising future for the intravesical installation in treatment of the superficial bladder cancer.

Characteristics and distribution of low molecular weight organic acids in the sediment porewaters in Bosten Lake, China

The composition and vertical profiles of low molecular-weight organic acids （LMWOAs） and the contribution of them to dissolved organic matter （DOM） in sediment porewaters in Bosten Lake, Xinjiang, China were investigated. The results showed that total concentration of LMWOAs was up to 94.5 μmol/L and their proportion in DOM was 5.6%, suggesting that LMWOAs were important chemical components in DOM in lake sediment porewaters. Among the seven LMWOAs, pyruvic and acetic acid had the highest concentrations with 26.30 and 8.31 μmol/L, accounting for 51.4% and 14.92% of LMWOAs, respectively. Trifluoroacetic and sorbic acid had the lowest concentrations, indicating that the compositions of LMWOAs in relative reducing environments were largely different from those reported in glacier, atmosphere and soils. The concentrations of lactic, acetic, formic, sorbic and oxalic acid decreased with increasing depth, probably relating to stronger microbial activities in the initial stage of early diagenesis. Trifluoroacetic acid was mainly anthropogenic with its concentration, showing a diusive trend from the surface to bottom sediments. The concentrations of lactic acid and nitrate generally showed a consistent profile. The increasing concentration of pyruvic acid in the vertical profile was just opposite to that of sulfate, revealing a significant negative relationship between them. Oxalic acid remained constant except for an obvious peak at 6 cm depth. The results indicated the diversities in sources and behaviors for various LMWOAs during early diagenesis in sediments.

Preparation and Characterization of AlginateHyaluronic Acid-chitosan based Composite Gel Beads

The aim of this study was to fabricate composite gel beads based on natural polysaccharides. Hyaluronic acid（HA） and Chitosan（CS） were successfully admixed with Ca^2＋/alginate（SA） gel system to produce SA/HA/CS gel beads by dual crosslinking： the ionic gelation and the polyelectrolyte complexation. The preparation procedure was that the weight ratio of SA（2%, m/v） to HA（2%, m/v） was kept at 2：1, then the mixture was dripped into the Ca^2＋ solution for ion-crosslinking, and finally polyelectrolyte crosslinked with 2% low molecular weight CS（LMW-CS） for 1.5 hours. The optimal formulation was achieved by adjusting the concentration and the weight ratio of SA, HA and LMW-CS. Due to the incorporation of HA and LMWCS, the swelling ratio of the beads at pH 7.4 was increased up to 120, and the time for the maximum swelling degree was prolonged to 7.5 h. The swelling behavior was obviously improved compared to the pure SA/Ca^2＋ system. The preliminary results clearly suggest that the SA/HA/CS gel beads may be a potential candidate for biomedical delivery vehicles.

Healing Effect and Underlying Mechanism of Silver Nanoparticles Prepared Using Carboxymethyl Chitosan under Solar Irradiation

In our previous study,silver nanoparticles were prepared using AgNO_(3) and carboxymethyl chitosan(CMCS)which is commercially available with solar irradiation.In this study,the efficacy and safety of silver nanoparticles prepared by this method were evaluated for healing wounds in rats with diabetes.We also attempted to determine the underlying mechanism and influencing factors of the silver nanomaterial preparation method.Compared with growth factors,silver nanoparticles exhibit better healing effects for rats with diabetes.No remnant silver ions were detected in the major organs of these rats after the application of silver nanoparticles.Silver nanoparticles prepared using CMCS are less toxic than those prepared from the conventional method,promote the proliferation of skin fibroblasts,and are promising as a topical medication for infected wounds.An obvious breakage process of the particles is observed during the growth of nanocrystalline silver in CMCS.In this study,we also attempted to determine whether this method is suitable for synthesizing silver nanoparticles using N-trimethyl chitosan chloride and sodium alginate were used in this particular experiment.The characteristic UV-vis absorbance peak of silver nanoparticles was found only in the reaction mixture containing N-trimethyl chitosan chloride.Our study demonstrates that free radicals are the key factor in this silver nanoparticle preparation method.

Green Synthesis and Physical and Chemical Characterization of Chitosans with a High Degree of Deacetylation, Produced by a Binary Enzyme System

Chitosan is a biopolymer obtained from chitin, where the N-acetylglucosamine monomer is in its deacetylated form; this polymer is useful for a wide variety of industrial applications. The properties and uses of chitosan depend on its physical and chemical characteristics, which result from the treatments used for its production. In this study, we report the preparation and characterization ofchitosan oligosaccharides by a green synthesis from crystalline shrimp chitin, using a sequential enzyme treatment by chitinase and chitin deacetylase. Chitinases were purified from grapes and used to rupture the crystalline shrimp chitin structure, modifying the crystallinity index from 57.6% to 15.9%. The resultant polymers were deacetylated using a recombinant chitin deacetylase from Saccharomyces cerevisiae, which was cloned and expressed in Pichia pastoris. The chitosans produced showed an estimated DA （degree of acetylation） of approximately 20%, and the molecular weights ranged from -7,600 to -3,700 after treatment in pH 3.0 and pH 6.0 for 10 min and 40 min, respectively. Physical and chemical characterization of the products indicated that enzyme fragmentation of chitin probably makes the acetamide groups more accessible to deacetylation, forming homogeneous polymers that are free of hazardous sub-products, have defined low molecular weights, and are highly deacetylated.

胺基改性壳聚糖吸附材料的制备及其对铀的吸附性能研究

研究了采用水热法制备壳聚糖微球(HTCC),再通过环氧化-胺化改性法制备胺基改性壳聚糖吸附材料(AHTCC)并用于吸附废水中的低浓度铀。利用红外光谱仪、元素分析仪、热重分析仪等对AHTCC的结构、组分和热稳定性进行表征,并考察了AHTCC对铀的吸附、解吸性能。结果表明:在pH=5~8条件下,AHTCC对溶液中铀的吸附效果较好;铀吸附平衡质量浓度为120 mg/L左右时,吸附量达最大,为151.6 mg/g;铀吸附速率在反应最初60 min较快,180 min时达到吸附平衡;以80 g/L Na_(2)CO_(3)+20 g/L NaHCO_(3)作解吸剂,铀解吸率为97.5%;对于含杂离子浓度较高的实际含铀废水,经AHTCC单次吸附,铀的去除率可达95.6%。

壳寡糖浸种对低温下江西铅山红芽芋脱毒试管芋萌发及生理代谢的影响

江西铅山红芽芋脱毒试管芋一般在1月至2月上旬晴天播种,“倒春寒”等低温胁迫会导致早播的江西铅山红芽芋脱毒试管芋生长缓慢,出苗周期变长,严重时会造成烂种死亡,出苗率降低,影响其产量。为提高播种期江西铅山红芽芋脱毒试管芋抗寒性,该研究利用植物组织培养和植物生理学的方法测定了壳寡糖浸种后低温下江西铅山红芽芋脱毒试管芋的萌发及其相关生理指标。结果表明:200~250 mg/L壳寡糖浸种可显著促进低温下江西铅山红芽芋脱毒试管芋的萌发。与低温对照相比,当浸种浓度为200 mg/L时,在内源激素方面,有利于低温下江西铅山红芽芋脱毒试管芋萌发过程中赤霉素、玉米素核苷、多胺和茉莉酸的积累,而不利于生长素和脱落酸的积累;在抗氧化方面,提高了超氧化物歧化酶、过氧化物酶、过氧化氢酶的活性,降低了丙二醛和过氧化氢的含量;在渗透调节方面,有利于可溶性糖、可溶性蛋白、脯氨酸的积累;在代谢关键酶方面,可提高脂肪酶、蛋白酶和α-淀粉酶活性以及三磷酸腺苷含量。因此,200 mg/L壳寡糖可以调控低温下江西铅山红芽芋脱毒试管芋内源植物激素和渗透调节物质含量、抗氧化酶和代谢关键酶活性,促进其在低温下的萌发。

花生芽苗菜贮藏品质变化及货架期预测模型

目的探究化学保鲜技术和低温保鲜技术对花生芽苗菜采后贮藏品质和生理特性的影响,建立其货架期预测模型。方法对比不同壳聚糖浓度下花生芽苗菜的感官品质,在此基础上分析不同贮藏温度下花生芽苗菜的果胶含量、纤维素含量、叶绿素含量、质构(硬度、脆度、咀嚼性)的变化情况;将果胶含量和纤维素含量作为特征指标,采用Arrhenius方程和化学动力学方程,建立花生芽苗菜货架期的动力学模型。结果经过质量分数为0.12%的壳聚糖溶液处理后的花生芽苗菜,在0℃下贮藏保鲜12d后,其果胶含量为(5.13±0.02)mg/L,纤维素含量为(1.09±0.06)%,硬度为(141.34±18.19)N,脆度为(141.34±18.19)N,咀嚼性值为(29.28±1.47)N,均显著高于其他温度处理组(P<0.05),且仍具有食用品质。之后在低温与化学保鲜复合技术的基础上,建立相应的货架期预测模型。结论花生芽苗菜果胶货架期和纤维素货架期整体平均误差(9.75%、2.88%)较低,花生芽苗菜预测模型整体准确度较高。利用所建立的预测模型,对花生芽苗菜的货架期进行预测,与实际货架时间之间的误差为±10%,该模型可用于预测0~25℃贮藏条件下花生芽苗的保鲜效果,对指导生产实践具有重要意义。

几丁糖联合小剂量糖皮质激素关节腔注射治疗早中期膝骨关节炎的临床疗效分析

目的:探讨几丁糖联合小剂量糖皮质激素关节腔注射治疗早中期膝骨关节炎的临床疗效。方法:回顾性分析2021年6月—2022年12月在南京医科大学第一附属医院骨科门诊就诊并随访的膝骨关节炎患者共164例。按治疗方式分为3组:A组(对照组,口服给药)55例,B组(几丁糖关节腔注射+口服给药)53例,C组(几丁糖联合小剂量糖皮质激素关节腔注射给药)56例。比较3组治疗前后的疼痛视觉模拟评分(visual analogue scale,VAS)、Lysholm评分、美国特种外科医院(Hospital for Special Surgery,HSS)评分和关节液炎性细胞因子白介素(interleukin,IL)-1、IL-6和肿瘤坏死因子(tumor necrosis factor,TNF)-α水平的变化,并对临床疗效进行评价。结果:所有病例均获得随访,随访时间7~12个月,无失访病例。每组治疗后的VAS评分、Lysholm评分、HSS评分和关节液炎性细胞因子IL-1、IL-6和TNF-α水平均优于治疗前,差异有统计学意义(P<0.05)。治疗前VAS评分、Lysholm评分、HSS评分和关节液炎性细胞因子IL-1、IL-6和TNF-α水平在3组间的差异无统计学意义(P>0.05);但治疗后各项指标在3组间的差异有统计学意义(P<0.05);两两比较显示,C组优于A、B两组,B组优于A组,差异均有统计学意义(P<0.05)。3组临床疗效评价比较,差异有统计学意义(P<0.05)。结论:几丁糖联合小剂量糖皮质激素关节腔注射治疗早中期膝骨关节炎临床疗效显著,具有创伤小,起效迅速,疗效持久的特点,同时避免了外用或口服非甾体类抗炎药的不良反应,作为一线治疗方案,建议在临床推广和使用。

CS-PAA/Zn^(2+)复合网络水凝胶的制备与性能

以壳聚糖(CS)和丙烯酸(AA)为原料、Zn^(2+)为配位离子,采用紫外光照射法制备了CS-聚丙烯酸(PAA)/Zn^(2+)复合网络水凝胶。通过FTIR、XRD、SEM对样品进行了表征,考察了AA与CS上的氨基(—NH_(2))物质的量比、Zn^(2+)溶液加入量对CS-PAA/Zn^(2+)溶胀能力、拉伸性能、细胞毒性和抗菌性能的影响。结果表明,CS-PAA/Zn^(2+)复合网络水凝胶是以CS链为主链,—NH_(2)为第一位点交联较短的PAA短链,减少了PAA的生成,形成第一网络;PAA短链上的—COOH为第二位点,利用Zn^(2+)的动态金属配位作用,形成第二网络。CS-PAA/Zn^(2+)复合网络水凝胶存在较均匀、平整的外侧结构和富有管道空间及孔隙的内部结构;当使用1.0 g CS为原料、n(AA)∶n(—NH_(2))=1.0∶1、0.01 mol/L的Zn^(2+)溶液加入量为4.0 mL时,制备的CS-PAA/Zn^(2+)复合网络水凝胶溶胀能力和拉伸能力最强,在p H=1的溶液中,最大溶胀度为87.2%,断裂伸长率为331.265%,同时保持了较好的细胞(MDA-MB-231细胞)活性与抗菌(大肠杆菌)性能,其细胞毒性低,细胞增殖率最低可达327.9%,具有良好的抗菌性能,添加Zn^(2+)后抑菌圈直径最大可达5 mm。

低压静电场协同壳聚糖处理对草莓贮藏品质的影响

为保持草莓采后贮藏品质,寻求绿色高效的贮藏方式,采用施加低压静电场协同壳聚糖涂膜(LVEFCS处理)处理方式贮藏草莓,与单一施加低压静电场(LVEF处理)、壳聚糖涂膜(CS处理)处理方式的贮藏效果相比较,设置常温贮藏(20℃)为空白对照(CK处理),测定草莓贮藏品质的变化。结果表明,贮藏3 d时LVEFCS和LVEF处理的草莓失重率和腐烂率均显著低于CS和CK处理,贮藏4 d时LVEF处理的草莓失重率和腐烂率均显著低于其他处理;3种处理均可延缓草莓可溶性固形物(TSS)、总酸(TA)、维生素C(V_(C))含量的降低,3种处理对草莓TSS的保持作用相近,LVEFCS和LVEF处理对草莓TA和VC含量的保持作用显著优于CS和CK处理;贮藏4 d时LVEFCS和LVEF处理的草莓丙二醛(MDA)含量均显著低于CS和CK处理。由此可见,LVEFCS和LVEF处理的保鲜效果优于CS和CK处理,低压静电场处理可较好地保持草莓的贮藏品质。该研究可为草莓贮藏保鲜研究应用提供参考。

壳聚糖酶解的研究

低聚水溶性壳聚糖具有许多独特的生理活性。本文对壳聚糖酶解制备低聚水溶性壳聚糖的研究进展进行了介绍 。

低聚壳聚糖及其金属配合物的抗O_2^(·-)活性研究

以 NBT/VB2 /蛋氨酸为 O· - 2 产生、检测体系 ,对自制低聚壳聚糖及其金属配合物进行了抗 O· - 2 活性研究 ,结果显示低聚壳聚糖及其金属配合物对 O· - 2 均具有明显的清除活性 .质量浓度为 0 .5× 1 0 - 2 g/m L时 ,壳聚糖对 O· - 2 的清除率达 80 .3 % ,其与氯化镧、醋酸铜、醋酸钴的配合物对 O· - 2 的清除率分别为98.9%、84.1 %、78.4% ;相同条件下 ,高分子壳聚糖和单糖对 O· - 2 没有明显的清除作用 ,清除率仅为 1 3 %、9.5 % .随着样品质量浓度降低 。

甲壳素类液晶高分子研究——低分子量壳聚糖溶致液晶性及分子量对液晶临界浓度的影响

研究了两种用酶降解法得到的低分子量壳聚糖样品(CS1和CS2)的溶致液晶性.用GPC并辅以质谱法确定了两样品的数均相对分子质量为622和2311 g/mol.在相对分子质量低至622的低分子量壳聚糖(相当于四糖)水溶液中仍发现了溶致液晶现象,并确定出相对分子质量为622和2311的低分子量壳聚糖液晶临界浓度为73%和36%(W/W%),这些结果与已报道的中、高分子量壳聚糖液晶临界浓度随分子量升高而降低的基本规律是一致的.实验结果与经典的KS理论预测值不符,因为低分子量壳聚糖的相对分子质量超过了KS理论对高分子临界浓度的预测范围.

低分子量壳聚糖制备与应用研究进展

低分子量壳聚糖因具有特殊的生物活性而日益受到人们的关注。本文概要介绍了近5年来国内外低分子量壳聚糖的研究进展,包括低分子量壳聚糖的制备方法,如酶降解法、酸水解法、氧化降解法、物理法等,以及低分子量壳聚糖在农业、医药、抗菌、化妆品、食品等方面的应用。

低分子量N,O-羧甲基壳聚糖的合成及吸湿保湿性能

采用不同反应温度、反应时间和低分子量壳聚糖与氯乙酸摩尔比,在非均相反应体系中合成了不同取代度的低分子量N,O-羧甲基壳聚糖。当反应温度为60°C,反应时间为4h,低分子量壳聚糖与氯乙酸投料比为1∶1.5时,目标产物的取代度可达71%。吸湿保湿性能测定表明:取代度越大,低分子量N,O-羧甲基壳聚糖的吸湿保湿性越好,在相对湿度为81%,取代度从27%增大到71%时,其吸湿性从32.14%增大到37.27%,保湿性从310.72%增大到348.69%。

低聚壳聚糖衍生物与BSA的作用研究

研究了具有生物相容性的低聚壳聚糖衍生物与活性药物牛血清白蛋白(BSA)之间的作用。合成了聚合度为20的窄分子量分布低聚壳聚糖(NLCS_(20))的3种衍生物:N-马来酰化低聚壳聚糖(MNLCS)、N-羧甲基低聚壳聚糖(CNLCS)和N-琥珀酰化低聚壳聚糖(SNLCS)。通过紫外光谱(UV)、荧光光谱和等温滴定微量热仪(ITC)研究了NLCS_(20)衍生物与BSA之间的相互作用。结果表明,BSA的构象在NLCS_(20)衍生物溶液微环境中没有发生变化,活性也没有受到影响。NLCS_(20)衍生物与BSA的作用过程是放热的且是自发进行的,主要作用力是氢键和疏水作用。说明低聚壳聚糖衍生物能够作为潜在的亲水药物如活性医药蛋白或氨基酸的运输载体。