具有抗菌功能的壳聚糖复合膜研究及应用

【作者】 王明力；

【导师】 赵德刚；

【作者基本信息】 贵州大学 ， 农药学， 2008， 博士

【摘要】 壳聚糖（CTS）是一种天然多糖类生物大分子,具有多种优良的功能性质和潜在的应用价值,其中最为引人关注的特性就是成膜性和抗菌防腐作用,这两种独特性质使其广泛应用于农药载体、涂膜保鲜、可食膜载体、生物可降解用膜等领域。但是,由于目的不同而对壳聚糖膜性质和功能具有不同的要求,壳聚糖由于分子结构的特点,其单膜对果蔬涂膜保鲜时,存在保水率较低的缺点,果实易失水焉萎,同时,抗菌防腐也达不到保鲜的要求,难以满足室温下果蔬保水保鲜的要求;当作为农药膜剂型的载体应用时,壳聚糖单膜的机械性能较弱,易龟裂、易破碎。上述壳聚糖的缺陷是其自身的结构和性质所致,拓宽壳聚糖的应用关键在于改善和提高其膜材的抑菌性能、保水率和机械强度。纳米氧化硅（SiOx）是一种无毒、无味、无污染的白色粉术非金属材料,是目前有机材料改性中应用最为广泛的无机纳米材料之一,其粒子粒径减小至纳米级会产生一系列特殊的效应。因此,利用纳米SiOx对壳聚糖进行改性,提高壳聚糖膜的强韧性和抑菌杀虫性、改善透水率和透气性,并将改性后的壳聚糖纳米SiOx复合膜应用于果蔬的采摘前后,使生长期的果蔬得到病虫害防治和采摘后的果蔬得到贮藏保鲜。本研究主要内容和结论如下。1.壳聚糖纳米SiOx复合膜性能的研究。利用纳米SiOx对壳聚糖进行改性,得到壳聚糖纳米SiOx复合膜（CTS-Fh）,并对涂膜结构进行红外光谱（IR）、X射线衍射（XRD）和电镜透射（TEM）等表征。结果表明:CTS-Fh中壳聚糖与SiOx粒子表面的大量羟基存在强烈的氢键相互作用,使其拉伸强度、断裂伸长率和直角撕裂强度较壳聚糖单膜分别提高了63.29%,45.38%和11.58%。同时,CTS-Fh的透光率和透气性等性能也得到改善,复合膜性能优于简单膜。2.壳聚糖纳米SiOx复合膜抑菌活性的研究。壳聚糖纳米SiOx复合膜（CTS-Fh）与壳聚糖单膜（CTS）抑菌实验表明:CTS-Fh对细菌如革兰氏阴性菌大肠杆菌（Escherichia coli.）和革兰氏阳性菌枯草芽孢杆菌（Bacillus subtilis）,真菌如酵母（Saccharomyces）和青霉（Penicillium）的抑菌效果明显好于CTS,抑菌率分别提高了22.34%、6.50%、36.49%和53.76%。同时CTS-Fh对植物致病菌如马铃薯晚疫病（Phytophthora infestans）、番茄灰霉病（Botrytis cinerea Pers.）、和辣椒枯萎病（Fusarium wilt）也有明显的抑制效果。3.壳聚糖纳米SiOx复合膜涂膜保鲜的应用研究。以透水率最小化为目标函数,采用二次回归旋转正交组合试验设计方法,建立单指标二次回归模型,得到壳聚糖纳米SiOx保鲜复合涂膜最佳配方,并对金秋梨和黄瓜进行室温下涂膜保鲜,分别测试室温条件下失水率、维生素C、呼吸强度、多酚氧化酶（PPO）、过氧化酶（POD）、超氧化物歧化酶（SOD）、好果率和保鲜时间。同时,分析了壳聚糖复合膜对金秋梨表皮形貌的影响,研究结果表明:当复合膜中壳聚糖用量1.547g、SiOx用量0.028g、单甘酯用量0.015g时,壳聚糖复合膜较壳聚糖单膜的透水率降低了73.13%;室温下果蔬保鲜时间得到明显延长,各项指标得到改善和提高,其中金秋梨由20d延长至60d,好果率为80.00%,黄瓜由6d延长至12d,好果率为95.12%。4.壳聚糖纳米SiOx复合膜对蚜虫杀虫活性的研究。室内毒力实验:CTS-Fh对蚜虫有良好的活性,抗蚜虫性能高于CTS（57.41%）,达到62.93%,提高了15%。田间试验:壳聚糖单膜、壳聚糖复合膜、壳聚糖复合-阿维混合液和0.18%阿维农药分别喷施金秋梨果树的药后1-7天,虫口减退率分别为53.04%、68.66%、90.52%和87.60%,该结果表明壳聚糖复合膜能够增强农药的药效和持续时间。5.壳聚糖纳米SiOx复合膜急性毒性试验研究。对昆明种二级小鼠进行急性毒性试验,结果表明:LD₅₀＞10.0g/kg BW,未发现任何试验动物出现中毒表现,未出现动物死亡,壳聚糖/纳米SiOx属实际无毒范围。6.壳聚糖复合膜农药剂型研究。无论是室内毒力试验,还是田间药效试验,壳聚糖复合膜都具有一定的杀虫活性,该结论表明:壳聚糖复合膜可作为农药应用于果蔬植物的病虫害防治,而成为无农残、安全的绿色农药;而且壳聚糖复合膜与农药混合后,利用壳聚糖的成膜功能,壳聚糖复合膜作为一种农药剂型可以更广泛地应用于农业生产中。更多还原

【Abstract】 The Chitosan （CTS）, a kind of natural polysaccharide biological macromolecule, has many outstanding properties and potential application in various areas. Its film forming ability and antibacterial preservation for vegetable and fruit are the most important features, which make it extremely important in the field of the coating to maintain fruits fresh, the film separation, eatable film carrier, the film for biological degradation and so on. So it is required that the CTS films must have different properties when used for different purposes. When the CTS is used to coat on fruits and vegetable to prolong their storage life, it has been forced to be associated with some shortcomings, such as a low moisture-holding rate, fruits dehydration due to its typical molecular structural feature. Moreover, simultaneous maintenance of quality of fruits and vegetabales, moisture control at room temperature cannot be achieved along with the desired anticorrosive microbial properties. When CTS is used as a film carrier, the mechanical strength of CTS film is weak, easily chapped or staved. The above mentioned limitations of CTS film are attributed to the structure of CTS molecule and its nature, therefore, in order to extend the application of CTS it is imperative to improve and enhance the moisture-keeping and the mechanical strength of the membrane. Nano-SiOx is non-toxic, tasteless, non-polluting. It is one of the most extensively used inorganic nano-materials in the present modification of application of organic materials. When its particle size is reduced to nanometer level, SiOx displays a series of special functions. Moreover, nano-SiOx has a large quantity of unsaturated linkage and hydroxyl functionality in the different linkage state, and the molecules within cluster is in the form of three dimensional chain structure, leading to some interaction between SiOx with certain groups or bases of high polymer material. This may help to improve the performances of the material to a great extent.Therefore, using nano-SiOx to carry molecular modification to Chitosan to enhance the film obdurabihty and antibacterial property, improve water penetration rate and permeability, and make it apply to the fruits and vegetables’ before harvestry and after harvestry. Fruits and vegetables from growing to postharvest storage all gain safe and effective protection. Primary coverage and main conclusions of the present research are as follows.1. Performance researches of Chitosan nano-SiOx composite films. Chitosan was modified by adding nano-SiOx, and then Chitosan nano-SiOx mixture （CTS-Fh） was coated to obtain films. Characteristics of the composite films were investigated by Infra-red spectroscopy （IR）, X-ray diffraction （XRD） and Transmission Electron Microscopy （TEM）. The results indicated that strong hydrogen bonds were formed between Chitosan and nano-SiOx. Compared with the non-modified Chitosan films, the tensile strength, elongation-at-break and orthogonal tear strength of modified composite films（CTS-Fh） increased by about 63.29%, 45.38% and 11.58% respectively. At the same time, transmittivity and permeability of CTS-Fh were also improved. The performance of the CTS-Fh films obviously surpassed that of the pure CTS films.2. Researches on antibacterial properties of Chitosan nano-SiOx composite films. The antibacterial property experiments of the CTS-Fh and the CTS indicated that modified Chitosan films had a more obvious effect than pure CTS films against bacterium such as Gram-negative bacteria E. coli （Escherichia coli.） and Gelanshi masculine fungus subtilis bud spore bacillus （Bacillus subtilis）, and fungus like yeast （Saccharomyces） and blue mildew （Penicillium）, the antibacterial rate reaching 22.34%、6.50%、36.49%和53.76%, respectively. Simultaneously CTS-Fh had an obvious function to control the growth of agricultural pathogenic bacteria like late blight of potato （Phytophthora infestans）, the tomato grey mold （Botrytis cinerea Pers） and the hot pepper wilt disease （Fusarium wilt）.3. The application in the storage of fruits and vegetables. Taking the permeation rate of water as objective function, the orthogonal rotation experimental design methods based on single quadratic regression were used for investigation and established a quadratic regression model, obtaining an optimal formula of CTS-Fh for coating Jinqiu pear and cucumber to prolong their storage life at room temperature. The rate of water loss, vitamin C content, respiratory strength, polyphenol oxidase （PPO）, peroxidase （POD）, superoxide dismutase （SOD）, good fruit ratio and fresh-keeping life were determined separately. At the same time, the influence of the composited Chitosan film on the surface morphology and the waxy no-smooth character of Jinqiu pear were analyzed. Research results indicated that when the ratio of Chitosan and SiOx and monoglyceride was 1.547 : 0.028 : 0.015, the permeation rate of composite films failed were 73.1% as compared to the pure membrane; the preservative life of treated fruits and vegetables had been significantly prolonged at room temperature. Various indexes had been improved, such as the preservative life of the Jinqiu pear was extended from 20 days to 60 days, and good fruit rate was up to 80.00%, and the preservative life of Cucumber was extended to 12 days from 6 days, and good fruit rate was 95.12%.4. Research on insectieidal activity of Chitosan nano-SiOx composite films against Aphid. The toxicity testing in laboratory showed: CTS-Fh films had good insectieidal activity against aphid. Its anti-insect （aphis） effect was higher than that of CTS （57.41%）, reaching to 62.93%, increasing by 15%. Field experiments showed that after pure CTS solution, CTS-Fh composite solution, CTS/AWei （a compound） mixture solution and 0.18% AWei （pesticide） were spayed on to Jinqiu pear trees, the levels of insects decreased evidently and fell to 53.04%, 68.66%, 90.52% and 87.60 respectively during 1-7 days after application. Results indicated that CTS/nano-SiOx composite films can strengthen the drug efficacy and the duration of pesticide.5. Acute toxicity test of Chitosan composite films. By adding an acceptable maximum amount of nano-SiOx to the Chitosan films following the formula, acute toxicity test of the film was carried on the Kunming second-level mouse. Results indicated that when the applied dosage was 10.0 g/kg BW, LD₅₀>10.0 g/kg BW after 2 weeks. It was discovered neither any presented animals died nor any were under intoxication. CTS-Fh composite film is safe and an innocuous material.6. Pesticide formulation rsearch of Chitosan nano-SiOx composite films. Whether the indoor toxicity tests, or the field pharmacodynamic experiments, CTS-Fh films had a certain degree of insectieidal activity. In conclusion, CTS-Fh films could be used as a pesticide to control diseases and insect pests of fruits and vegetables, and proved to be a green pesticide which was at a lower residual level. When CTS-Fh films mixed with pesticides, taking advantage of the function of chitosan’s film isformation, CTS-Fh films as a pesticide agent can be more widely used in agriculturalproduction.更多还原