O-羧甲基化壳聚糖季铵盐的制备及抑菌活性

目的：制备抑菌活性较壳聚糖强的水溶性壳聚糖衍生物。方法：以3-氯-2-羟丙基三甲基氯化铵(CTA)和氯乙酸为接枝改性剂,制备水溶性O-羧甲基化壳聚糖季铵盐,采用红外光谱和紫外光谱对其结构进行表征,并研究O-羧甲基化壳聚糖季铵盐对大肠杆菌(E.coli)、金黄色葡萄球菌(S.aureus)和黑曲霉(A.niger)的抑制作用。结果：水溶性的O-羧甲基化壳聚糖季铵盐对E.coli、S.aureus和A.niger均有显著的抑菌活性。结论：与壳聚糖相比,水溶性的O-羧甲基化壳聚糖季铵盐的抑菌活性提高。     

壳聚糖羧甲基化条件的优化

对壳聚糖的羧甲基化条件进行了优化。通过单主正交试验，考察了氯乙酸用量、碱化时间、反应温度对产品羧甲基取代度、外观等理化指标的影响，得出羧甲基化的最佳条件为：碱化时间2.5h，羧甲基化反应时间4h，反应温度40℃，4M氯乙酸用理70ml，制备的羧甲基壳聚糖呈白色粉末，羧甲基取代度达0.898，水溶性较壳聚糖有较大改善。     

壳聚糖基医用补片的制备及其性能研究

以梭子蟹蟹壳为原料,经预处理、浸酸脱钙质、碱煮脱蛋白和浓碱脱乙酰化制备壳聚糖膜;再在碱性条件下使壳聚糖膜和氯乙酸发生取代反应,制备羧甲基化壳聚糖膜.采用电位滴定法测试羧甲基化壳聚糖膜的取代度.测试壳聚糖膜和羧甲基化壳聚糖膜的溶胀性、吸水性、润湿性和抗菌性.结果表明:制备的羧甲基化壳聚糖膜的取代度为1.86,其溶胀性和吸...     

壳聚糖羧甲基化条件的优化

对壳聚糖的羧甲基化条件进行了优化。通过单因素及正交试验 ,考察了氯乙酸用量、碱化时间、反应温度对产品羧甲基取代度、外观等理化指标的影响 ,得出羧甲基化的最佳条件为 :碱化时间 2 .5h ,羧甲基化反应时间 4h ,反应温度 40℃ ,4M氯乙酸用量 70ml,制备的羧甲基壳聚糖呈白色粉末 ,羧甲基取代度达 0 .898,水溶性较壳聚糖有较大改善     

羧甲基壳聚糖制备纸用微囊的研究

对壳聚糖进行羧甲基化,通过提高其水溶性及高分子性能,根据单凝聚法以羧甲基壳聚糖作为微囊壁材,结晶紫内酯作为芯材进行包囊,考察了羧甲基化后的壳聚糖对制备纸用微囊粒径及其均一性的影响。     

应用于纸张增强的羧甲基化壳聚糖的合成研究

羧甲基化壳聚糖是制浆造纸行业中应用十分广泛的造纸化学助剂。随着中国造纸行业的迅速发展,其应用领域也不断拓展。羧甲基化壳聚糖可用于纸张增强,它既可增加纸张的干强度,也可以提高纸张的湿强度。研究了羧甲基化壳聚糖的合成并将其用于纸张增强,研究了不同因素对取代度的影响,对产物进行了红外光谱的表征,并将产物用于纸张的增强实验以验证效果。     

纸张增强用羧甲基化壳聚糖的应用研究

本研究通过比较不同抄造条件下,如羧甲基化壳聚糖的用量,不同取代度的羧甲基化壳聚糖,以及对于不同浆料等变量条件下所抄造的纸张来考察对强度的影响。研究表明,对于漂白针叶木浆,当羧甲基壳聚糖的取代度为1．02附近时,纸张的裂断长达到最大,纸张的撕裂指数、耐破指数和耐折度都有不同程度的增加,对于苇浆基本上趋于一致。而随着羧甲基化壳聚糖的用量的增加,无论是是针叶浆还是苇浆,纸张强度较空白样都有提高。     

两亲性壳聚糖/改性结冷胶复合膜的制备与表征

为开发性能更优、可生物降解的食品保鲜材料,以壳聚糖和结冷胶为原料制备可食用性复合膜.该研究通过羧甲基化和胆酸化改性壳聚糖,使其具有两亲性,并使改性后壳聚糖易溶于水;再进行羧甲基化改性结冷胶,使其在常温下为均一水溶性材料,不再形成凝胶状,利用傅里叶红外光谱,核磁氢谱等对其结构进行表征;该研究以改性壳聚糖为主要成膜材料,结...     

羧甲基壳聚糖──一种多用途的甲壳素衍生物

羧甲基壳聚糖── 一种多用途的甲壳素衍生物夏文水吴焱楠（食品科学与工程系）０前言羧甲基壳聚糖（Ｃａｒｂｏｘｙｍｅｔｈｙｌｃｈｉｔｏｓａｎ，ＣＭｃｈｉｔｏｓａｎ）是壳聚糖（Ｃｈｉｔｏｓａｎ）经羧甲基化反应后的一类甲壳素（Ｃｈｉｔｉｎ）衍生物，由于壳聚糖?..     

两性壳聚糖的制备及其对纸张的增强作用

以壳聚糖-环氧丙基三甲基氯化铵(CTS-ETA)进行羧甲基化改性,制得两性壳聚糖;制备羧甲基化CTS-ETA的优化条件为:m(氯乙酸)∶m(CTS-ETA)=1.5∶1,碱化时间为1h,醚化时间为3h,醚化温度为60℃。将自制改性壳聚糖应用于成纸物理强度的增强,结果表明:两性壳聚糖可用作纸张的增强剂,加入少量(质量分数为0.2%~0.3%)就能对纸张的物理强度有很大的提高。     

超声波法制备两性壳聚糖衍生物及其抗菌性能

应用超声波辐射的方法,使壳聚糖和氯乙酸在Na0H-乙醇体系中反应,制备0-羧甲基壳聚糖（OCMC）．测定了四因素三水平正交试验中的羧甲基取代度（DS）和氨基（N2-）保留量（％）,优化了实验条件．选择较好的OCMC,以乙醇为溶剂,在超声波辐射下,通过和2,3一环氧丙基三甲基氯化铵（GTA）反应,合成具有抗菌性能的两性的季铵化D羧甲基壳聚糖（QOCMC）,并测定其季铵化取代度．红外光谱仪表征了其峰值的变化,扫描电镜表征其晶态结构的变化．通过对大肠杆菌和金黄色葡萄球茵最低抗茵浓度测试,得到QOCMC的最低抑茵浓度为OCMC的1／8,表明QOCMC的抗茵性能优于OCMC．     

壳聚糖及其衍生物对油豆角保鲜效果的研究

分别用壳聚糖和羧甲基壳聚糖配制的涂膜液处理油豆角,比较不同处理组的生理指标及感官指标,确定保鲜效果较好的涂膜液。结果表明,涂膜处理的油豆角呼吸强度、多酚氧化酶和过氧化物酶活性及丙二醛含量与对照组相比都有所降低;用N,O羧甲基壳聚糖处理的油豆角保鲜效果较好。     

O-羧甲基壳聚糖的合成、抑菌性能及对细胞膜蛋白的影响

通过红外光谱、热重-差热对合成的O-羧甲基壳聚糖进行了表征,并研究了壳聚糖及O-羧甲基壳聚糖对革兰氏阳性菌和阴性菌的抑制作用。此外,采用紫外-可见吸收光谱、荧光光谱研究了O-羧甲基壳聚糖对细胞膜蛋白的影响。结果表明:水溶性的O-羧甲基壳聚糖对阴沟肠杆菌、枯草芽孢杆菌的抑菌性能较壳聚糖更强,对粪肠杆菌的抑制作用稍弱,而对金黄色葡萄球菌、肺炎克罗伯杆菌和大肠杆菌几乎没有抑制作用;O-羧甲基壳聚糖对细胞膜蛋白的荧光具有猝灭作用。     

Chitosan-based edible coatings for quality preservation of postharvest whiteleg shrimp (Litopenaeus vannamei)

Postharvest shrimp is highly susceptible to both microbiological spoilage and endogenous enzymatic browning, so it should be preserved properly using effective and appropriate methods. The effects of 1.0% and 1.5% O-carboxymethyl chitosan (CMC) and 1.0% and 1.5% chitosan (CH) coatings on the quality changes of whiteleg shrimp (Litopenaeus vannamei) during refrigerated storage (0 ± 1 °C) of 10 d were investigated. The pretreatment with CMC and CH solution (1.0% or 1.5%) retarded growth of psychrophilic bacteria throughout storage in comparison with the control (P < 0.05). The lower increases in pH and total volatile base (TVB) content were obtained in the shrimp treated with CMC and CH solution at both levels, compared with the control samples (P < 0.05). Loss in freshness and melanosis decreased after the shrimp was treated with CMC and CH. In addition, CMC and CH (1.0% or 1.5%) showed inhibitory activity toward total viable bacteria counts of white shrimp in a dose-dependent manner. Therefore, chitosan and O-carboxymethyl chitosan can be used as promising melanosis inhibitors as well as antimicrobial agents during refrigerated storage. PRACTICAL APPLICATION: The main practical application behind the development of chitosan (CH) and O-carboxymethyl chitosan (CMC) used to preserve postharvest whiteleg shrimp lies with the fact that these polysaccharides represent a renewable source of natural biodegradable polymers and meet with the emergence of more and more food safety problems. Both CMC and CH can be used as food preservatives to extend shrimp shelf life. However, CMC is more convenient due to its solubility. In the future, CMC will be used in the food processing industry because of its soluble, compatible, antimicrobial, and antioxidative characteristics.     

壳聚糖和N,O-羧甲基壳聚糖对金黄色葡萄球菌抑菌活性的研究

目的研究壳聚糖及N，O-羧甲基壳聚糖的抑菌活性。方法金黄色葡萄球菌经24h摇瓶培养后，接种到含一定量壳聚糖或N，O-羧甲基壳聚糖的肉汤培养基中，通过测定0h、4h、8h、12h、16h、20h、24h、28h、32h、36h光密度值，研究浓度、分子量、脱乙酰度、取代度及pH、温度、盐对壳聚糖和N，O-羧甲基壳聚糖抑制金黄色葡萄球菌活性的影响。结果壳聚糖和N，O-羧甲基壳聚糖的抑菌活性受浓度、分子量、脱乙酰度、取代度及溶液pH、温度和盐的影响。结论壳聚糖和N，O-羧甲基壳聚糖抑菌活性受以上因素影响。     

羧甲基壳聚糖在秀丽线虫体内的抗衰老作用

目的:基于模式动物秀丽线虫探究羧甲基壳聚糖的抗衰老能力。方法:检测羧甲基壳聚糖处理前后,秀丽虫寿命、运动能力、吞咽频率以及排泄周期的变化,同时测定过氧化氢酶和谷胱甘肽过氧化物酶的活力,判断羧甲基壳聚糖线虫体内抗氧化的能力。结果:500和1000 mg/L羧甲基壳聚糖分别能显著(P<0.05)和极显著(P<0.01)延长秀丽线虫的寿命,而500 mg/L能够极显著(P<0.01)提高秀丽线虫运动能力活跃度,加速咽泵运动,缩短排泄周期。同时,100、500和1000 mg/L羧甲基壳聚糖均能极显著(P<0.01)提高秀丽线虫过氧化氢酶和谷胱甘肽过氧化物酶的活力。结论:500 mg/L的羧甲基壳聚糖抗衰老作用较好强,具有抗氧化、抗衰老的应用前景。     

Response surface methodology in the optimization of tea polyphenols-loaded chitosan nanoclusters formulations

Response surface methodology was used to optimize tea polyphenols-loaded chitosan nanoclusters preparation conditions, including carboxymethyl chitosan concentration, chitosan hydrochloride concentration and amount of tea polyphenols. The responses particle size and entrapment efficiency of nanoclusters were studied. The optimum conditions of carboxymethyl chitosan concentration, chitosan hydrochloride concentration and amount of tea polyphenols were found to be 3.63, 1.19 and 10.94 mg/mL, respectively. The optimized particle size was 301 nm, and entrapment efficacy of nanoclusters was added up to 83.7%. The results demonstrated that Box–Behnken design methodology was an effective way to obtain the optimal formulation of tea polyphenols-loaded chitosan nanoclusters, and the nanoclusters complexation synthesizing through ionic gelation between carboxymethyl chitosan and chitosan hydrochloride was good biomaterials, which could be successfully used to encapsulate tea polyphenols.     

Rapid detection of Salmonella in milk by a nuclear magnetic resonance biosensor based on the streptavidin-biotin system and O-carboxymethyl chitosan target gadolinium probe

Rapid and sensitive detection of foodborne pathogens is of great importance for food safety. Here, a set of nuclear magnetic resonance (NMR) biosensors based on a O-carboxymethyl chitosan target gadolinium (Gd) probe was developed to quickly detect Salmonella in milk by combining NMR technology and bioimmunotechnology with membrane filtration technology. First, O-carboxymethyl chitosan (O-CMC) was biotinylated to prepare biotinylated O-carboxymethyl chitosan (biotin–O-CMC) through amide reaction, and biotinylated magnetic complexes (biotin–O-CMC–Gd) were obtained by using O-CMC, which has strong chelating adsorption on Gd. The target probe was obtained by combining biotin–O-CMC–Gd with the biotinylated antibody (biotin–antibody) via streptavidin (SA) by introducing the SA–biotin system. Then, Salmonella was captured by the target probe through antigen–antibody interaction. Finally, NMR was used to measure the longitudinal relaxation time (T₁) of the filtrate collected by membrane filtration. This NMR biosensor with good specificity and high efficiency can detect Salmonella with the sensitivity of 1.8 × 10³ cfu/mL within 2 h; in addition, it can realize the detection of complex samples because of its strong anti-interference capability and may open up a new method for rapid detection of Salmonella, which has a great application potential.     

羧甲基壳聚糖对啤酒酵母脱苦的特性研究

为了脱除啤酒酵母泥中主要的苦味,利用羧甲基壳聚糖(CMCS)吸附啤酒酵母泥中的苦味物质,研究表明在35 min内,羧甲基壳聚糖对破壁的酵母泥脱苦速率大于未破壁酵母泥的脱苦速率。通过傅里叶变换红外(FT-IR)光谱仪对吸附前后羧甲基壳聚糖的表征以及对羧甲基壳聚糖吸附啤酒酵母中苦味物质过程中的吸附热力学特性、吸附动力学的分析,研究了羧甲基壳聚糖对啤酒酵母脱苦特性。结果表明:羧甲基壳聚糖脱苦未破壁和破壁酵母泥的化学基团可能相同,羧甲基壳聚糖对啤酒酵母泥脱苦过程中参加反应的主要基团是-COOH,-OH也参与了反应。羧甲基壳聚糖对未破壁和破壁的啤酒酵母泥的吸附热力学特性符合Langmuir等温线性模型,吸附动力学过程遵循拟二级动力学模型,吸附过程以单层化学吸附为主。     

O-羧甲基壳聚糖的制备及对黑曲霉生长的影响

采用红外光谱法对合成的O-羧甲基壳聚糖(OCMC)进行表征,研究壳聚糖及OCMC对黑曲霉生长的影响。结果表明：当培养基中添加OCMC,作用第1天时,可以有效的抑制黑曲霉菌落的生长;当OCMC质量浓度为1.0mg/mL时,对黑曲霉生长的抑制能力最强;壳聚糖和OCMC能与ct-DNA发生相互作用,导致ct-DNA双螺旋结构被破坏。