【作者】 高向华；

【导师】 许并社；

【作者基本信息】 太原理工大学 ， 材料科学与工程， 2013， 博士

【摘要】 微生物对传统抗生素耐荮性日渐增强,人们对抗菌材料、抗菌制品的需求不断增加。纳米银无机抗菌剂具有抗菌力强、耐久性好、抗菌谱广、不易产生耐药性、安全性高等特点,因而作为一种长效、安全的高效无机抗菌剂,在生物医学领域中得到越来越广泛的应用。但纳米银粒子粒径小,表面活性高,在制备过程中极易团聚,导致应用时失去纳米颗粒应有的物性和功能。将纳米银(Ag)粒子与天然可降解生物高分子复合后制备的抗菌溶胶,既可保证纳米Ag粒子的均匀分散,又可提高纳米Ag粒子的抗菌稳定性,该溶胶具有天然、安全和可降解的优势,可拓宽其在生物医药领域中的应用。因此,本论文以硝酸银(AgNO3)为前驱体,壳聚糖(Chitosan,简写为CTS)和淀粉(Starch,简写为ST)作为稳定剂和保护剂,采用液相反应法和微波辅助加热法,通过不同的还原剂,制备了一系列纳米银／天然高分子复合抗菌溶胶。1.采用一种简单的液相化学反应法,以可溶性淀粉为保护剂,以硼氢化钠(NaBH4)为还原剂,在加热搅拌条件下,制备了纳米银／淀粉(Ag/ST)核壳复合颗粒及纳米Ag/ST复合溶胶；讨论了制备工艺如淀粉用量、还原剂浓度、反应温度、反应时间和pH值对形成的纳米Ag/ST溶胶的影响。结果表明：在ST用量为0.5%(质量比),NaBH4/Ag+离子的摩尔比为2：1,初始溶液的pH值为8.0的条件下,使用NaBH4强还原剂制备的纳米Ag/ST复合粒子的粒径小、分布均匀、稳定性好；该复合颗粒呈核壳结构,颗粒粒径为5-20nm, ST壳厚度为2nm。2.以绿色环保的葡萄糖为还原剂,淀粉为保护剂,用液相化学还原法制备了纳米Ag/ST的复合抗菌溶胶。结果表明初始溶液的pH值、葡萄糖用量是影响反应产物形貌的重要因素。较好的制备工艺是:AgNO3浓度为0.05-0.10mol/L,葡萄糖与AgNO3用量比为3：1,温度为70℃条件下反应120min。制备的纳米Ag/ST复合粒子仍呈球形核壳结构,平均粒径约为25nm,粒径分布均匀。但由于葡萄糖为弱还原剂,纳米Ag/ST的产率相对较低。3.以柠檬酸钠(Sodium Citrate简写为Citra)为还原剂,淀粉为保护剂,用液相化学还原法制备了纳米Ag/ST核壳结构的复合抗菌溶胶。结果表明：较好的制备工艺是Citra与AgNO3摩尔比为3：1,温度为70℃条件下反应120min。制备的纳米Ag/ST复合粒子大部分呈球形,少量为椭球形核壳结构,粒径约在30nm。4.利用CTS为稳定剂和柠檬酸钠为还原剂,在微波辐射条件下绿色合成纳米银/壳聚糖(Ag/CTS)复合溶胶。结果表明：CST/Ag+为3：1(摩尔比)、pH值为6-7、微波辐射功率为中火、辐照时间为25min左右时,所得球形银纳米粒子径小、粒径约30nm左右。5.以大肠杆菌(E.coli)和金黄色葡萄球菌(S.aureus)为测试菌种,用抑菌圈法和最小抑菌浓度(MIC)研究了纳米Ag/ST和Ag/CTS复合溶胶的抗菌性能。结果表明：该复合溶胶具有优良的抗菌活性,银粒子的尺寸越小、分布越均匀,其抗菌活性也越强；通过化学还原法、微波法制备的纳米Ag/ST和Ag/CTS溶胶的MIC分别为125ppm和300ppm,两者的杀菌率均超过了99.9%；Ag/CTS复合抗菌剂具有比单一抗菌剂更高效的抗菌性能；探讨了Ag纳米粒子和CTS的复合抗菌机理,二者具有协同抗菌作用。综上所述,所制备的纳米Ag/ST和Ag/CTS复合溶胶作为一种天然无机抗菌材料,无毒,可降解,并具有优异的抗菌性能,可广泛应用于纺织品和生物医药领域。更多还原

【Abstract】 Demands for antibacterial materials and products have been increased when the drug resistance of microorganism is wide-spreaded. Silver nanoparticles (Ag NPs) as an inorganic antimicrobial agent, widely used in biomedical fields, possess high antimicrobial activity, good durability, broad antibacterial spectrum, low drug resistance and security. However, Ag NPs easily aggregate because of the high surface activity, which finally leads to a functional loss of nanoparticles. The dispersity and stability of Ag NPs can be greatly improved by the coverage of polymers, which is bound to expand the application of Ag NPs in biomedical fields. In this study, a series of Ag NPs/polymer compounds were synthesized by using silver nitrate as precursor, chitosan (CTS) and starch (ST) as protective agents. Moreover, the liquid phase reaction method and microwave radiation were used to obtain the AgNPs/polymer compounds.1. Nano-Ag/ST core-shell particles and nano-Ag/ST sols were prepared through a simple chemical reaction method by using ST as protective agent and NaBH4as reductant. The formation of Ag/ST sols was influenced by ST dosage, concentration of reductants, temperature, reaction time and the pH value. The results showed that the Ag/ST particles with small size, narrow size distribution and high stability were obtained under the condition of ST dosage of0.5g, molar ratio of NaBH4/AgNO3in2:1and the pH value of7.0. The complex particles had core-shell structures in size of5-20nm, with2nm of ST shell.2. Nano-Ag/ST sols were prepared through liquid phase reaction method by using ST as protectant and glucose as reductant. The morphology of nano-Ag/ST was affected by the pH value and the glucose concentration. The results showed that the optimum reaction conditions were the concentration of AgNO3solution in0.05-0.10mol/L, the molar ratio of glucose to AgNO3in3:1, the reaction time of10minutes and the temperature of70℃. The prepared particles were in uniform core-shell structure with the mean size of25nm.3. Ag/ST sols are synthesized by liquid phase reduction method by using sodium citra (Citra) as reductant. The optimal synthesis parameters are the molar ratio of Citra to AgNO3in3:1, the reaction temperature of70℃for120min. The most prepared Ag/ST particles presented a spherical core-shell structure in mean size of30nm and few ones were ellipsoidal.4. Nano-Ag/CTS complex sols were synthesized by microwave heating using sodium citrate as reductant and CTS as protectant. The results showed that spherical Ag NPs in mean size of30nm were prepared under conditions of molar ratio of CST to Ag in3:1, the pH value of6.0and microwave heating time of25min under medium and low power.5. The antibacterial performances of Ag/ST and Ag/CTS were tested by inhibition zone method and minimal inhibitory concentration (MIC) method, and E.coli and S. Aureus were selected as experimental strains, respectviely. The inhibition zone test showed that both of the two compounds had a great antibacterial activity. Moreover, the smaller and the more uniform the particles were, the stronger the antimicrobial activity was. The MIC of Ag/ST and Ag/CTS sols prepared by chemical reduction method and microwave method were125ppm and300ppm, respectively, and the bactericidal rates of the two compounds were greater than99.9%, indicating excellent antibacterial activities of Ag/ST particles. Additionally, Ag/CTS compounds presented higher antibacterial performance than that of Ag NPs or CTS used alone. The antibacterial mechanisms of Ag NPs and CTS were studied. The great antibacterial activities of Ag/CTS sols were due to the synergistic action of Ag NPs and CTS.In summary, as natural inorganic antimicrobial materials, nano-Ag/ST and-Ag/CTS sols have advantages of great antibacterial activities, biodegradability and nontoxicity, which are favor of their application to textile and biomedical fields.更多还原