负载纳米银磺化聚醚砜超滤膜的制备及其抗菌性

为了改善聚醚砜(PES)膜的抗污染性能,将PES磺化并制成超滤膜,然后将超滤膜浸渍在硝酸银溶液中,吸附Ag~+的超滤膜在维生素C的还原作用下将Ag负载在膜表面,制备了负载纳米银磺化超滤聚醚砜膜(SPES-Ag)。通过扫描电镜(SEM)、原子力显微镜(AFM)、X射线衍射(XRD)对SPES-Ag超滤膜进行了表征,并通过细胞吸附法进行了抗菌性测试。结果表明,纳米银的平均尺寸为120 nm,它的负载提高了超滤膜的抗菌性能,对大肠杆菌、假单胞菌和金黄色葡萄球菌的抗菌率分别达到了96.7%,98.3%,87.7%。此外,水通量和截留率的测试结果表明,SPES-Ag超滤膜的水通量为438.4 L/(m~2·h),对牛血清蛋白(BSA)的截留率达到94.3%。     

谷氨酰胺转移酶处理对大豆分离蛋白、酪蛋白酸钠和明胶可食膜特性的影响

研究了谷氨酰胺转移酶(TGase)对大豆分离蛋白(SPI1和SPI2)、酪蛋白酸钠(NaCN1和NaCN2)及明胶(G1和G2)3类蛋白质成膜特性的影响。研究表明在成膜溶液中加入TGase(8U/g蛋白),可以使SPI、NaCN和明胶等3类蛋白质膜的抗拉强度和表面疏水性有不同程度的改善,其中抗拉强度增加的辐度为13.1%(P≤0.05),而表面疏水性增加的辐度为2%～216%(P≤0.05);明显降低了膜的水分含量、总可溶性物量及透光率。对于断裂伸长率,TGase的处理使G1膜、NaCN2膜、G2膜、NaCN1膜和SPI2膜分别增加16.3%、16.8%、43.0%、72.6%和440.5%,而使SPI1膜降低7.5%。SDS-PAGE电泳分析表明TGase使这3类蛋白质均产生了共价交联。     

基于壳聚糖/银离子的可逆温敏水凝胶的制备与性能

以壳聚糖(CS)和Ag NO₃为主要原料,通过CS与Ag⁺的超分子络合作用制备了一系列可逆温敏CS-Ag水凝胶,采用FTIR、XRD、XPS、SEM和EDS对CS-Ag水凝胶的结构和化学状态进行了表征。结果表明,通过同时调节Ag NO₃用量和体系p H可制备具有相同凝胶温度的CS-Ag水凝胶。当CS用量为0.60 g、Ag NO₃用量为0.19 g、体系总体积为21 m L、保持水凝胶p H=4.24时,制备的CS-Ag-19水凝胶凝胶温度为50℃,具有最佳的热可逆性能,至少可循环相变5次,具有室温避光保存5个月的稳定性,并表现出对大肠杆菌良好的抗菌性能。CS-Ag-19的溶胶-凝胶转换是由CS的氨基在不同温度下的超分子相互作用控制,H⁺和Ag⁺在温度、浓度变化的驱动下,对游离氨基的竞争反应(质子化和络合作用)之间的平衡关系使水凝胶具有温敏可逆性。CS-Ag-19水凝胶的可注射和温敏凝胶性能使其具有作为水凝胶抗菌敷料的应用潜力。     

基于多糖交联的层层自组装抗菌膜制备及表征

采用多糖聚合物壳聚糖(CHI)、羧甲基纤维素(CMC)和纤维素纳米晶(CNC)为成膜材料,借助静电相互作用为驱动力的层层自组装(LBL)技术,进而通过多糖分子间化学交联提升薄膜稳定性,设计制备了一种CHI/CMC/CNC纳米复合薄膜,并考察了其抗菌性能。通过扫描电子显微镜、台阶仪、傅里叶变换红外光谱仪和接触角测量仪分别对薄膜表面形貌、厚度、粗糙度、材料构成和表面浸润性进行综合表征。结果表明,层层自组装多层膜被成功制备,(CHI/CMC)₂₀-(CHI/CNC)₅膜厚度约为702.6 nm,原始水滴接触角为48.8°,化学交联后变为14.7°。细胞毒性测试表明多糖交联的CHI/CMC/CNC薄膜具有高度生物相容性。来自动物多糖的正电壳聚糖和亲水表面赋予了多糖交联薄膜良好的抗菌性能,其能显著抑制大肠杆菌(E.coli)、金黄色葡萄球菌(S.aureus)和白色念珠菌(C.albicans)的表面黏附、聚集和生长。     

空气除湿用抗菌透湿复合膜的制备

为提高膜式全热交换器的除湿性能并使膜具备抗菌性能,以Li Cl为亲水添加剂,Ag NO3为抗菌剂,添加到聚乙烯醇（PVA）水溶液中制成铸膜液,以聚丙烯（PP）膜为支撑层,制备了一种抗菌透湿复合膜。搭建了薄膜透湿性测量平台,测试了复合膜的水蒸气透过量,对复合膜的抗菌性进行了检测。结果表明,复合膜的水蒸气透过量随Li Cl含量的增加而增加,Li Cl含量为5%的复合膜是不含Li Cl复合膜的1.79倍,是商用纸膜的2.67倍。加入Ag NO3后薄膜的透湿性没有明显变化,抗菌实验结果显示,复合膜对表皮葡萄球菌、大肠杆菌有抗菌作用,对表皮葡萄球菌的抗菌作用更强。     

聚多巴胺功能化纳米银粒子制备及抗菌性能

采用一步法,以聚多巴胺(PDA)为还原剂和保护剂,制备PDA功能化的纳米银粒子(PDA-nanoAg)。提出PDA-nanoAg合成机理,并考察其在水相中的分散稳定性。通过紫外-可见吸收分光光度计(UV-Vis)、透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FTIR)对产物形貌和结构进行表征。采用肉汤稀释法测试PDAnanoAg的抗菌性能。结果表明,所制备的PDA-nanoAg平均粒径为50 nm,具有良好的稳定分散性;对埃希氏大肠杆菌(E.coli)、金黄色葡萄球菌(S.aureus)的最小抑菌浓度(MIC)为7.56 mg/L,最小杀菌浓度(MBC)为30.24mg/L。     

可食性蔬菜膜的制备与性能研究

本实验以新鲜蔬菜为主要原料,研究了不同添加剂对蔬菜膜性能的影响,并通过正交实验得出可食性蔬菜膜的最佳工艺配方:蔬菜浓度40%,CMC浓度0.6%,卡拉胶浓度0.1%,甘油浓度0.6%,制备的可食性蔬菜膜性能综合指标最高。     

聚多巴胺功能化纳米银粒子制备及抗菌性能研究

采用一步法,以聚多巴胺(PDA)为还原剂和保护剂,制备PDA功能化的纳米银粒子(PDA-nanoAg)。提出PDA-nanoAg合成机理,并考察其在水相中的分散稳定性。通过紫外-可见吸收分光光度计(UV-Vis)、透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FTIR)对产物形貌和结构进行表征。采用肉汤稀释法测试PDAnanoAg的抗菌性能。结果表明,所制备的PDA-nanoAg平均粒径为50 nm,具有良好的稳定分散性;对埃希氏大肠杆菌(E.coli)、金黄色葡萄球菌(S.aureus)的最小抑菌浓度(MIC)为7.56 mg/L,最小杀菌浓度(MBC)为30.24mg/L。     

聚丙烯微孔膜表面AgCl修饰层的构建及其抗菌性

通过多巴胺氧化聚合修饰及交替浸渍技术在聚丙烯微孔膜(MPPM)表面构建了Ag Cl修饰层。采用FTIR、XPS对构建过程膜表面的化学变化进行了分析;采用SEM-EDX对膜表面形态及Ag Cl分布进行了考察;通过表面水接触角及水通量的测定分析了膜的亲水性;采用平板活菌计数法评价了膜对大肠杆菌及金黄色葡萄球菌的抗菌能力。结果表明,制得的修饰膜具有强的抗菌能力和良好的表面亲水性,其对大肠杆菌和金黄色葡萄球菌的抗菌率分别达99.2%和100%。     

微孔聚丙烯膜表面季铵化及其抗菌性能

为了赋予微孔聚丙烯膜(MPPM)抗菌能力,发展了一种有效的表面季铵化方法。基于紫外光引发丙烯酸的接枝聚合,通过碳二亚胺活化,将聚亚乙基亚胺(PEI)共价固定于MPPM表面,用环氧丙烷对PEI链上的伯胺和仲胺进行叔胺化,最后再和苄氯反应,成功地使MPPM表面季铵化。采用FTIR、XPS、荧光素二钠盐染色和水接触角对膜进行了表征。采用平板活菌计数法考察了季铵化膜对大肠杆菌和金黄色葡萄球菌的抗菌性能。结果显示,季铵化膜对大肠杆菌和金黄色葡萄球菌均具有强的抗菌活性;增加膜表面阳离子密度或延长接触时间,均能有效提高膜的抗菌能力。     

Large-Scale Preparative Isolation of Rosavin from Rhodiola rosea via Ion Liquids MAE and Subsequent Flash Adsorption Chromatography

Rosavin was a major active compound from Rhodiola rosea. It is known that it possesses stimulant, antidepressant, and anticancer properties. In the present study, a two-step flash column chromatography has been developed for the large-scale preparative separation and purification of rosavin from the extracts of Rhodiola rosea, which were obtained by microwave assisted extraction (MAE) using ion liquids (ILs) as extraction solvent under the optimized conditions (microwave power 1200 W, extraction time 6 min, solid-liquid ratio 1:20, microwave temperature 120°C) resulting from the analysis of the D-optimal design. In the first separation, the Rhodiola rosea extract was loaded into polyamide and HPD-200 macroporous resin flash columns in series for efficient enrichment of rosavin. In the second one, the rosavin-rich crude sample after the serial column chromatography was subjected to final purification by silica gel flash chromatography. After the two-step separation, 529.1 mg of rosavin was obtained at a purity of 98.2% and a recovery of 60.6%. The separation process can provide a new method for large-scale separation and purification of rosavin for its pharmaceutical and practical use.     

抗氧化菌的筛选及混菌发酵红景天条件优化

通过测定12株酵母菌的谷胱甘肽(GSH)含量、超氧化物歧化酶(SOD)活力和羟基自由基清除能力以及8株乳酸菌的总还原力和超氧阴离子自由基清除能力,分别筛选出抗氧化性强的产朊假丝酵母(酵母菌Y1)和干酪乳杆菌(乳酸菌L8)。比较了14种中药经混菌(酵母菌Y1和乳酸菌L8)发酵前后酪氨酸酶抑制率和总还原力的变化,得出红景天为最佳发酵中药。以红景天为原料,采用纤维素酶-果胶酶酶解后添加其他营养成分,以酪氨酸酶抑制率为指标,采用响应面法优化混菌发酵红景天的条件:葡萄糖质量分数12.35%、液料比18.67∶1(mL∶g)、发酵时间5.25 d,在此条件下红景天发酵液酪氨酸酶抑制率为73.21%,比未发酵的提高了67.72%。     

大米蛋白可食性膜的制备工艺研究

大米蛋白膜是一种绿色包装膜,它具有良好的阻气性、阻油性、保香性、防湿性和防紫外线性,因此开发大米蛋白膜具有重大的意义.作者对大米蛋白的成膜条件进行了研究.结果表明,大米蛋白在质量分数80％乙醇中溶解效果良好,在40℃恒温条件下,可以在光滑的不锈钢板上形成具有一定强度的可食性薄膜.此外,添加油酸与甘油可以对膜的透明度与抗...     

Application of osmotic dehydration and microwave drying to strawberries coated with edible films

Osmotic dehydration (OD) is one of the conventional methods to increase the shelf-life of vegetables and fruits. However, the operating conditions can adversely affect the organoleptic and nutritional quality of fresh products due to the high sugar uptake during processing and the loss of water-soluble constituents to the osmotic medium. The application of edible films has attracted interest due to their ability to reduce the entry of solutes and simultaneously increase the removal of water during OD treatments. Microwave (MW) is one of the most effective emerging technologies to accelerate dehydration processes in vegetable matrices. This aspect is particularly relevant in strawberries, given its high content in bioactive and nutritional compounds. Thus, the aim of this paper was to assess the influence of edible film application (alginate–lactate) in strawberry slabs during combined OD-microwaves dehydration processes. Samples of 1?cm thickness were treated with sucrose solution (60°Bx, 40?°C, 4?h) and then were dehydrated in a microwave oven (1.2?W/g). The application of alginate–lactate edible films resulted in similar weight and water losses but lower solids gain compared to uncoated samples during OD treatment. OD pre-treated MW-dried strawberry slabs with moisture contents up to 0.15?kg dry basis were obtained after 100?min of MW drying. Besides, the effective diffusional coefficient (D_e) was estimated for MW drying process, values ranged from 4.5 to 8.8 10^?10 m²/s when shrinkage effect was considered, and from 1.1 to 2.3 10^?9 m²/s for constant thickness assumption.     

Physicochemical and antibacterial properties of chitosan‐polyvinylpyrrolidone films containing self‐organized graphene oxide nanolayers

Chitosan films have a great potential to be used for wound dressing and food‐packaging applications if their physicochemical properties including water vapor permeability, optical transparency, and hydrophilicity are tailored to practical demands. To address these points, in this study, chitosan (CS) was combined with polyvinylpyrrolidone (PVP) and graphene oxide (GO) nanosheets (with a thickness of ～1 nm and lateral dimensions of few micrometers). Flexible and transparent films with a high antibacterial capacity were prepared by solvent casting methods. By controlling the evaporation rate of the utilized solvent (1 vol % acidic acid in deionized water), self‐organization of GO in the polymer matrix was observed. The addition of PVP to the CS/GO films significantly increased their water vapor permeability and optical transmittance. A blue shift in the optical absorption edge was also noticed. Thermal analysis coupled with Fourier transform infrared spectroscopy suggested that the superior thermal stability of the nanocomposite films was due to the formation of hydrogen bonds between the functional groups of chitosan with those of the graphene oxide. An improved bactericidal capacity of the nanocomposite films against gram‐positive Staphylococcus aureus and gram‐negative Escherichia coli bacteria was also observed. Highly flexible, transparent (opacity of 6.95), and antimicrobial CS/25 vol % PVP/1 wt % GO films were prepared. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43194.     

Effect of stearic acid and sodium stearate on cast cornstarch films

Stearic acid and sodium stearate were used as lipids to form inclusion complexes with cornstarch through a cooking process, respectively. The complexing index and the surface tension of the cooked pastes were measured. The films of the pastes were formed by casting, paper‐sizing, and paper‐coating methods. X‐ray diffraction and scanning electron microscopy were used to characterize the crystal and surface structures. Such properties of the complex films as the moisture absorption, friction coefficient, and tensile properties were tested. The results reveal that the two lipids could form an inclusion complex with amylose in the cornstarch more or less as a result of forming V‐type crystals that restrained the crystallite size of the B‐type crystal in the starch film. The addition of lipids reduced the sensitivity of the complex films to environmental moisture, decreased the friction coefficient of the films, and visibly increased the smoothness of the surfaces of the films. When the lipids were added in the starch at a weight content of 1%, the elongation at break of the complex film increased and the strength decreased slightly, and above a 1% content of the lipids, the tensile properties of the starch film were greatly deteriorated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Chitosan from Muga silkworms (Antheraea assamensis) and its influence on thermal degradation behavior of poly(lactic acid) based biocomposite films

The research work is focused on extraction of chitin from Muga silkworms (MS) and its conversion into chitosan by chemical treatment process. The extracted amount of chitin and chitosan from MS were obtained ～8 wt % and ～7 wt %, respectively. Potentiometric titrations, conductometric titrations, elemental analysis, ¹H‐NMR and FTIR analyses were employed to calculate the degree of deacetylation of chitosan (extracted at 80 ºC after 10 h) and found as 77% ± 2, 81% ± 1.8, 82% ± 2.4, 97.77% ± 0.3, and 82% ± 1.8, respectively. The deacetylation process of chitin showed pseudo‐first order reaction kinetics and activation energy was estimated as ～15.5 kJ/mole. The extracted chitosan (at 80 ºC after 10 h) showed higher crystallinity and improved thermal stability with respect to chitosan extracted from other marine sources. Subsequently, poly(lactic acid) (PLA) and extracted chitosan dispersed biocomposite films were prepared by solution casting method. Significant dispersion of chitosan (extracted at 80 ºC after 10 h) micro‐particles were observed in biocomposite films using FESEM analysis. Due to chitosan interaction with PLA, significant reduction in thermal degradation and activation energy was observed during nonisothermal degradation scan of such films using Flynn‐Wall‐Ozawa and Kissinger‐Akahira‐Sunose models. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43710.     

Effect of oxidation level on the dual modification of banana starch: The mechanical and barrier properties of its films

Banana starch was oxidized at three different levels and then acetylated. The double‐modified starch was used for film preparation. The physical, mechanical, and barrier properties were tested. The oxidation level increased the whiteness of the film, and the second modification (acetylation) did not affect this parameter. The solubility increased with temperature and oxidation level. However, acetylation decreased the solubility value. At the longest storage times, the solubility decreased because of starch reorganization inside the polymeric matrix. In general, oxidation increased the tensile strength of the films, and a slight increase was observed when the oxidized starch was acetylated. This effect was more noticeable at the longest storage time. The oxidation level decreased the percentage elongation at break, and a slight effect due to acetylation was observed. The film of oxidized–acetylated starch showed a higher elastic modulus value than its oxidized counterpart. The water vapor permeability increased with oxidation level, but the acetylation decreased this parameter. The oxidation increased the hydrophilic character of the starch because of the formation of carbonyl and carboxyl groups that showed more affinity for water molecules. When the oxidized banana starch was acetylated, a decrease in the water vapor permeability was found because the acetylation increased the hydrophobic character of the starch due to the ester group. Films prepared with the double‐modified banana starch had some improved physical, mechanical, and barrier properties, and they may be used in specific applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

PC/MWCNT纳米复合薄膜的制备及性能研究

将表面功能化的多壁碳纳米管(g-MWCNT)添加到质量分数8%聚碳酸酯(PC)的三氯甲烷溶液中,经室温浇筑挥发成膜后,得到光学透明性良好的复合薄膜。经UV-VIS法测定薄膜的透光率得出,当g-MWCNT的添加量为0.05%时,透光率≥85%,弹性模量比纯PC薄膜提高13%,极限拉伸强度与纯PC相当。通过扫描电镜表征和增强机理分析得出,力学性能的提升可归因于碳纳米管的桥接作用和PC-MWCNT界面结合机理。