不同分子量壳聚糖抑菌作用的研究

随着壳聚糖研究的不断深入,其不同寻常的抑菌活性引起了学者们的广泛关注。为了获得壳聚糖对桉树青枯病病原菌极其拮抗菌的抑制活性,在研究中考察了不同分子量的壳聚糖对桉树青枯病的生防菌302-多粘类芽孢杆菌、199-蜡状芽孢杆菌及桉树白枯病的病原菌76-茄青枯拉尔氏菌、RS-桉树青枯病原菌的抑制效果。采用琼脂扩散纸片法研究了不同浓度和分子量的壳聚糖对上述4种菌的抑制效果,利用了系列稀释法研究了不同分子量的壳聚糖的最小抑菌浓度。同时研究了分子量为2200的壳聚糖在不同pH条件下的抑菌效果。结果表明,5种不同分子量的壳聚糖对76-茄青枯拉尔氏菌和RS-桉树青枯病病原菌有明显的抑制作用,其中分子量为2200和5万的壳聚糖对青枯病原菌的抑菌效果最好,且随壳聚糖浓度的增大,壳聚糖的抑菌作用逐渐增强,最小抑菌浓度在0.05%以上。而这2种分子量的壳聚糖对302-多粘类芽孢杆菌和199-蜡状芽孢杆菌的抑菌效果较上述2种病原菌要明显弱很多,最小抑菌浓度在0.1%以上。在上述试验的基础上,本试验进一步探讨了分子量为2200的壳聚糖在不同pH条件下对4种受试菌的抑制效果。结果表明,当pH在5.5~6.5时,对受试菌具有最佳的抑制效果。壳聚糖对上述4种菌的作用效果尚未见文献报道。     

Effect of dietary chitosan on haematology,innate immunity and disease resistance of Asian seabass Lates calcarifer (Bloch)

This study was performed to evaluate the effect of dietary chitosan on haematology, innate immunity and protection against Vibrio anguillarum in Asian seabass, Lates calcarifer. A basal diet supplemented with 0, 5, 10 and 20 g chitosan kg^?1 diet was fed to the four different groups for 60 days. The haematological (total erythrocyte count, total leucocyte count, total serum protein, albumin, globulin and albumin‐globulin ratio) and innate immune parameters (phagocytic ratio, respiratory burst, serum lysozyme and serum bactericidal activities) were monitored at fortnight interval to assess the effect of chitosan feeding in Asian seabass. All the studied haematological and innate immune parameters were increased significantly (P ≤ 0.05) in chitosan‐fed groups in comparison with control. However, the group fed diet containing 10 g chitosan Kg^?1 feed showed highest haematological and innate immune parameters on 45^th day in comparison with other groups. Moreover, the fish fed the diet containing 10 g chitosan Kg^?1 feed had significantly higher post‐challenge survival (75.56 ± 4.44%) on the 30th day following V. anguillarum challenge. Therefore, this study suggests that chitosan at 10 g kg^?1 diet could be used as prophylactic in Asian seabass culture to enhance the protection against any possible infection by V. anguillarum.     

Chitosan composites for bone tissue engineering--an overview

Bone contains considerable amounts of minerals and proteins. Hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] is one of the most stable forms of calcium phosphate and it occurs in bones as major component (60 to 65%), along with other materials including collagen, chondroitin sulfate, keratin sulfate and lipids. In recent years, significant progress has been made in organ transplantation, surgical reconstruction and the use of artificial protheses to treat the loss or failure of an organ or bone tissue. Chitosan has played a major role in bone tissue engineering over the last two decades, being a natural polymer obtained from chitin, which forms a major component of crustacean exoskeleton. In recent years, considerable attention has been given to chitosan composite materials and their applications in the field of bone tissue engineering due to its minimal foreign body reactions, an intrinsic antibacterial nature, biocompatibility, biodegradability, and the ability to be molded into various geometries and forms such as porous structures, suitable for cell ingrowth and osteoconduction. The composite of chitosan including hydroxyapatite is very popular because of the biodegradability and biocompatibility in nature. Recently, grafted chitosan natural polymer with carbon nanotubes has been incorporated to increase the mechanical strength of these composites. Chitosan composites are thus emerging as potential materials for artificial bone and bone regeneration in tissue engineering. Herein, the preparation, mechanical properties, chemical interactions and in vitro activity of chitosan composites for bone tissue engineering will be discussed.     

低聚糖激发子的制备及诱导杨树抗病性的研究

采用正交实验优选H2O2氧化降解壳聚糖的最佳工艺条件,得到最佳降解方案:30%H2O2用量10 mL,反应温度60℃,反应时间6 h,乙酸浓度2%。在此基础上用壳聚糖及低聚糖溶液作为激发子诱导杨树抗病性,当低聚糖浓度为10 mg/L时,PAL、β-1,3-葡聚糖酶、几丁质酶及木质素活性达到最高值分别为对照的3.41、3.89、3.12、2.56倍。SOD、CAT及POD活性分别为对照的4.01、2.59、2.65倍。壳聚糖最佳诱导浓度为20 mg/L,此时PAL、β-1,3-葡聚糖酶、几丁质酶及木质素酶活性分别为对照的3.15、3.85、3.02、2.56倍。SOD、CAT及POD活性分别为对照的3.81、2.43、2.59倍。相同浓度的低聚糖与壳聚糖相比诱导效果更好。     

壳聚糖锰配合物的吸附动力学

为了更好地发挥壳聚糖与锰本身独特的生物活性,将壳聚糖与锰盐反应,制备了壳聚糖锰配合 物。采用分光光度法测定了锰的含量,研究了壳聚糖对锰的吸附动力学行为。结果表明,在一定浓度 范围内,壳聚糖（CTS）对锰的吸附符合Langmuir 和Freundlich 等温吸附模型,pH=3.5 时吸附20 h 的饱和 吸附量为Qmax=3.099 g/g,吸附平衡常数K=120.4 L/g,吸附焓变ΔH=16.81 kJ/mol。在35℃时,壳聚糖对 锰的吸附符合吸附动力学一级反应方程,且求得吸附表观活化能Ea=29.08 kJ/mol,初始锰质量浓度为1 g/L 时,Langmuir 一级速率常数k 为0.396 h-1。试验为壳聚糖锰配合物的进一步应用研究工作,提供了一 些基础理论数据。     

壳聚糖对沙棘种子萌发的影响

用0.05%、0.1%、0.2%、0.3%4种浓度壳聚糖乙酸溶液对沙棘种子浸种处理24h,以未处理种子为对照。测定了种子的发芽率、发芽势、发芽指数和活力指数及幼苗的根长、苗高、鲜重和干重,并对种子萌发过程中α-淀粉酶、脱氢酶、过氧化物酶、过氧化氢酶活性及幼苗叶绿素的含量等生理指标进行了测定。结果表明,壳聚糖对沙棘种子的萌发和幼苗生长具有促进作用,随着处理浓度的增大各项指标先升高后降低,其最佳处理浓度为0.1%,当浓度达到0.3%时,表现出一定的抑制作用。     

Inhibition of Botrytis cinerea growth and suppression of botrytis bunch rot in grapes using chitosan

Chitosan inhibited growth of Botrytis cinerea in liquid culture and suppressed grey mould on detached grapevine leaves and bunch rot in commercial winegrapes. Germination of B. cinerea was completely inhibited in malt extract broth containing chitosan at concentrations greater than 0·125 g L^?1. However, treated conidia were able to infect detached Chardonnay leaves and pathogenicity was not affected, even after incubation for 24 h in chitosan at 10 g L^?1. When added after conidial germination, chitosan inhibited B. cinerea growth and induced morphological changes suggestive of possible curative activity. The effective concentration of chitosan that reduced mycelial growth by 50% (EC₅₀) was 0·06 g L^?1. As a foliar treatment, chitosan protected detached Chardonnay leaves against B. cinerea and reduced lesion diameter by up to 85% compared with untreated controls. Peroxidase and phenylalanine ammonia‐lyase activities were also induced in treated leaves. In vineyard studies, Chardonnay winegrapes exhibited 7·4% botrytis bunch rot severity at harvest in 2007 after treatment with an integrated programme that included chitosan sprays from bunch closure until 2 weeks preharvest, compared with 15·5% in untreated controls and 5·9% with fungicide treatment. In the following season, botrytis bunch rot severity was 44% in untreated Chardonnay at harvest and the integrated programme (21%) was less effective than fungicides (13·8%). However, in Sauvignon blanc winegrapes, the integrated and the fungicide programme each reduced botrytis bunch rot severity to 4% and were significantly different from the untreated control (11·5%). This study provides evidence that suppression of botrytis in winegrapes by chitosan involves direct and indirect modes of action.     

壳聚糖处理诱导黄连木种子的萌发

为解决黄连木种子萌发困难的问题,运用双因素多水平重复试验设计,开展壳聚糖处理诱导黄连木种子萌发试验。壳聚糖浓度水平为0.2%、0.4%、0.6%、0.8%、1.0%,浸种时间分别为1、2、3、4 d,用蒸馏水浸种作对照。结果表明：没有经过处理的黄连木种子很难萌发,壳聚糖可诱导种子提前萌发;壳聚糖溶液浓度对种子萌发的影响显著,以浓度为0.2%的效果较好;壳聚糖浸种时间对种子萌发的影响达到极显著水平,以浸种1 d种子发芽率和发芽指数最高,浸种2 d的种子发芽势最高;壳聚糖溶液浓度和浸种时间的交互作用对种子发芽率、发芽势、发芽指数的影响效果均达到显著水平,经0.6%的壳聚糖溶液浸种1 d的处理效果最佳。     

Novel Spray Dried Glycerol 2-Phosphate Cross-Linked Chitosan Microparticulate Vaginal Delivery System—Development,Characterization and Cytotoxicity Studies

Chitosan microparticulate delivery systems containing clotrimazole were prepared by a spray drying technique using glycerol 2-phosphate as an ion cross-linker. The impact of a cross-linking ratio on microparticle characteristics was evaluated. Drug-free and drug-loaded unmodified or ion cross-linked chitosan microparticles were examined for the in vitro cytotoxicity in VK2/E6E7 human vaginal epithelial cells. The presence of glycerol 2-phosphate influenced drug loading and encapsulation efficacy in chitosan microparticles. By increasing the cross-linking ratio, the microparticles with lower diameter, moisture content and smoother surface were observed. Mucoadhesive studies displayed that all formulations possessed mucoadhesive properties. The in vitro release profile of clotrimazole was found to alter considerably by changing the glycerol 2-phosphate/chitosan ratio. Results from cytotoxicity studies showed occurrence of apoptotic cells in the presence of chitosan and ion cross-linked chitosan microparticles, followed by a loss of membrane potential suggesting that cell death might go through the mitochondrial apoptotic pathway.     

新生牛血中Cu/Zn-SOD的提纯及肝素、壳聚糖的逐层自组装包裹

试验旨在通过对超氧化物歧化酶（super oxide dismutase, SOD）改性,提高其稳定性。本试验采用了热变性提取方法从新生牛血中提取Cu/Zn-SOD,采用逐层自组装技术,以肝素与壳聚糖为材料,对从新生牛血中分离提纯的SOD进行物理包裹试验,并对包裹后Cu/Zn-SOD的稳定性进行研究。结果显示,在耐热稳定性上,包裹的SOD相对酶活性比天然SOD提高了3.3倍;在耐酸碱性方面,在pH分别为3.0、11.0的条件下,包裹的SOD相对酶活性较天然SOD提高了2.0倍;在抗胰蛋白酶水解的能力上,包裹的SOD相对酶活性较天然SOD提高了2.7倍。采用肝素、壳聚糖制成的外壳对SOD进行物理修饰可得到较好的效果,且其具有较强的机械强度、生物相容性较好,外表面的壳聚糖有助于帮助跨细胞膜转运,可应用于口服剂型SOD的开发。