大豆分离蛋白与壳聚糖复合材料的制备

蛋白质与多糖的静电作用是生物体内一个基本医学-化学现象,是实现自组装的主要驱动力,可利用这种非共价作用设计和构筑理想的微结构。 以大豆分离蛋白(Soybean Protein Isolates,SPI)和壳聚糖(Chitosan,CS)为原料,采用浊度法考察了配比、溶液pH值、离子强度和温度对SPI与CS在溶液中相互作用的影响。 结果显示,由于pH值影响静电作用强度,从而成为影响SPI与CS相互作用的主要因素,其中,当pH值为5.5~6.6时,SPI与CS可以实现有效结合。在较低的离子强度下,有利于形成具有紧凑结构的CS/SPI聚集体,较高离子强度下聚集体发生解离。 蛋白质受热发生变性,多肽链上的疏水氨基酸残基暴露在溶液中,导致与壳聚糖链的疏水作用增强。 DLS结果显示,CS与SPI自组装形成了分布均一的纳米粒子,变性后的SPI与CS形成的纳米粒子粒径有所增大,分布均一;经戊二醛交联,粒径有所减小。 SEM显示,壳聚糖单层膜表面存在龟裂现象,与SPI形成双层膜后龟裂消失;同时,单层膜厚度约为300 nm,双层膜厚度约为500 nm。     

反应性嵌段共聚物自组装制备无机纳米粒子研究进展

具有"核-壳"结构的嵌段共聚物胶束具有广泛的用途.本文介绍了反应性嵌段共聚物的自组装技术应用于制备具有独特的光、电、磁等以及催化特性的无机纳米粒子,特别是介绍了近年来在制备纳米贵金属粒子的研究进展.     

碱式碳酸铜微球的表面改性和组装

报道了通过分散聚合反应在碱式碳酸铜微球表面锚接聚苯乙烯纳米粒子, 以调节其亲水/亲油性的方法. 结果表明, 锚接的聚苯乙烯纳米粒子尺寸愈大, 所得的改性碱式碳酸铜微球疏水性愈强. 用对油和水润湿性适中的改性碱式碳酸铜微球为乳化剂, 能够制备出稳定的油包水型Pickering乳液. 改性碱式碳酸铜微球组装在Pickering乳液的分散相液滴表面, 形成一个固体壳层. 将Pickering 乳液的分散相水核凝胶化, 合成出分级结构琼脂糖凝胶微球.     

光敏性无规-类接枝双亲聚合物的合成与自组装行为的研究

通过ε 己内酯改性丙烯酸酯 (FAn ,n =1～ 4 )与肉桂酰氯反应合成了一系列光敏性大单体 (FAnC ,n =1～ 4 ) ,以FAnC与甲基丙烯酸 (MAA)进行自由基聚合 ,制备具有光敏性的双亲无规 类接枝共聚物 (PMFAnC) .用红外光谱、凝胶渗透色谱、核磁共振和差示扫描量热仪等对共聚产物进行了表征 .双亲性PMFAnC可以在选择性溶剂中进行自组装 ,形成以PMFAnC中PFAnC疏水链段为核 ,PMAA亲水链段为壳的高分子胶束 .核内的肉桂酰基由紫外光引发发生光交联反应 ,得到具有稳定壳 核结构的胶束 .动态激光光散射、透射电子显微镜结果表明 ,PMFAnC在水溶液中形成了一定结构的光敏性纳米胶束 ,在紫外光照射下PMFAnC胶束内核发生光聚合反应使胶束粒径减小     

具有可见光响应聚合物纳米粒子的制备及性能研究

利用可见光响应供体-受体Stenhouse加合物(DASAs)设计并制备了2种表面含有可见光响应单元的聚合物纳米粒子,并对纳米粒子的光响应性进行了研究.首先合成了修饰DASA分子的聚合物PGMD,研究结果表明PGMD可溶于与水互溶的有机溶剂(如DMSO)中并具有良好的光响应性,PGMD链段可在可见光刺激下响应为亲水状态.因此,含有PGMD链段的嵌段共聚物PCL-b-PGMD可在水中自组装形成胶束,并能与PCL-b-PEG在水中共组装形成复合壳层胶束,但PGMD链段在水中无法可逆响应为疏水状态.为获得具有可逆响应性的聚合物纳米粒子,利用硅烷偶联剂水解修饰的方法得到表面含有疏水三烯状态DASA分子与亲水PEG短链的复合壳层二氧化硅纳米粒子,实验结果表明复合壳层二氧化硅纳米粒子在水环境中有良好的分散稳定性,并且表面修饰的DASA分子仍具有良好的响应性.本研究为设计表面性质可调的响应性聚合物纳米粒子提供了新的设计思路.     

聚合物-纳米金在油水界面的自组装及有序结构的构筑

聚合物-纳米金复合物既具有金纳米粒子的光、电及催化性能,又具有聚合物的可加工性及对外界的刺激响应性,因此已成为高分子科学及材料科学研究的热点。本文主要介绍了我们实验室在聚合物-纳米金在油水界面的自组装及有序结构的构筑研究方面的相关工作:(1)利用界面聚合的方法制备侧链接枝亲水性金纳米粒子的聚苯乙烯及杂化聚合物在水溶液中的自组装;(2)亲水性金纳米粒子及疏水性聚合物(或疏水性磁性纳米粒子)在油水界面的自组装研究;(3)利用金纳米粒子为交联点制备具有温度响应性聚合物微凝胶的研究。     

以PEO-b-PAN嵌段共聚物胶束作模板合成SiO_2-C纳米复合材料

通过阴离子聚合和活性自由基聚合相结合的方法,合成了聚环氧乙烷-聚丙烯腈两亲性嵌段共聚物(PEO-b-PAN).PEO-b-PAN嵌段共聚物在水溶液中自组装形成胶束正硅酸乙酯以胶束作模板进行溶胶-凝胶过程,形成SiO2/PEO-b-PAN复合材料.随后经300℃预氧化,1000℃高温炭化,得到SiO2-C纳米复合材料.用1HNMR、IR、GPC、TGA、TEM、SEM等技术对嵌段共聚物及SiO2-C纳米复合材料进行了表征,结果表明SiO2-C复合材料的结构为SiO2为壳C为核的纳米粒子,粒子的直径为(55±5)nm.     

PLGA-PEG共聚物负载多西紫杉醇的药物输运体系的计算机模拟

采用耗散粒子动力学模拟的方法研究了抗癌药物输运体系多西紫杉醇与聚乙丙交酯与聚乙二醇的共聚物(PLGA-PEG)的自组装形态, 考察了共聚物浓度、共聚物组成和药物含量等对自组装形态的影响. 模拟结果表明, 不同浓度的PLGA-PEG能够和多西紫杉醇自组装成球状、柱状、层状等结构; 一定的浓度下, 亲水的PEG嵌段将疏水的PLGA嵌段包裹起来形成核壳结构, 可用于疏水药物输运应用. 在比较低的浓度下, 不同组成的PLGA-PEG均会形成球状核壳结构, PEG嵌段较多时壳层较厚核尺寸较小, PLGA嵌段较多时核的尺寸较大但壳层较薄, 综合考虑载药量和稳定性, 模拟结果中PEG嵌段的摩尔分数为60%即PLGA₄₀-PEG₆₀作为载体时性能较佳. 药物的含量对自组装结构也有影响, 药物含量较小时形成球状结构, 药物含量较大时, 则会形成柱状结构. 对PLGA₄₀-PEG₆₀体系, 模拟结果显示药物、聚合物和水的最佳配比为5:10:90. 本工作可为共聚物载药体系的设计与开发提供参考.     

基于PAA-b-PAN嵌段共聚物胶束制备磁性碳纳米粒子

本文采用原子转移自由基聚合方法合成了聚丙烯酸叔丁酯-聚丙烯腈嵌段共聚物(PtBA-b-PAN),酸解得到聚丙烯酸-聚丙烯腈两亲嵌段共聚物(PAA-b-PAN).随后,PAA-b-PAN嵌段共聚物在水溶液中自组装形成以PAA为壳,PAN为核的胶束.用此胶束为模板,加入FeCl3溶液后得到了壳层负载Fe3+的聚合物纳米粒子,经230℃空气中预氧化,600℃氮气氛煅烧,得到了核壳结构的,具有磁性的碳纳米粒子.用1HNMR,IR,GPC,TGA,TEM,XRD,AGM等技术对嵌段共聚物及纳米粒子进行了表征,结果表明纳米粒子的壳层含γ-Fe2O3,Fe2.5C混合物,核含碳,直径为35±5nm,饱和磁化强度为2.16emu/g.在分离、吸波和传感器等方面具有潜在的应用前景.     

具有疏水核/亲水壳的双亲胶体粒子的制备

制备了具有疏水性聚苯乙烯核/亲水性聚丙烯酰胺壳的双亲粒子.疏水核通过超浓乳液聚合制备,亲水壳层通过过氧化羟基异丙苯和硫酸亚铁的界面引发制备.控制条件可得到网孔(半包覆)、褶皱(全包覆)两种形态的壳层.壳层孔的存在使得核层聚合物能够与外界接触.粒子的双亲性通过吸水吸油率进行表征.     

Enzymatically modified Soy Protein

Optimum temperature and pH for the isolation of soy protein isolate (SPI) from soy protein concentrate (SPC) were established. Enzymatic hydrolysis of SPI with enzymes of different specificities such as trypsin, chymotrypsin, papain and urease was carried out and the products of hydrolysis were characterized by molecular mass determination [sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)] and thermal techniques [differential scanning calorimetry (DSC) and thermogravimetric analysis (TG)]. Enzymatic hydrolysis resulted in a significant reduction in molecular masses. However the thermal stability of hydrolysed SPI was similar to native SPI indicating that it is independent of molecular mass. DSC studies indicated an increase in temperatures of endothermic transition associated with SPI denaturation and loss of absorbed moisture in samples of lower molecular masses. This revised version was published online in August 2006 with corrections to the Cover Date.     

气相色谱-质谱对天然酿造酱油与配制酱油香气成分的分析比较

利用蒸馏萃取/气相色谱-质谱(SDE/GC-MS)方法对酱油香气成分进行了分析,在4种不同工艺生产的酱油中共鉴定出51种化学成分,其中醇类12种、酚类5种、醛酮8种、酸类6种、酯类7种、杂环化合物类13种,同时发现,3种酿造酱油中的共有成分为35种.不同工艺生产的酿造酱油中醇、酚、醛酮、酯类物质的种类均比配制酱油多1倍以上,酸类物质的总含量也远大于配制酱油,但配制酱油的杂环类风味物质比较丰富,主要为体现烤香风味的吡嗪类化合物.乙醇、2-甲基丙醇、3-己醇、3-甲硫基丙醇、苯乙醇、乙烯基-2-甲氧基-苯酚、4-乙基-苯酚、α-亚乙基-苯乙醛、香草醛、2-羟基丙酸乙酯、乙酸乙酯、乙酸苯甲酯、亚油酸乙酯、5-甲基糠醇、3-苯基呋喃为酿造酱油的特有成分.构成酱油特征香气成分的4-乙基愈创木酚、糠醇、糠醛等物质的含量在配制酱油中也相对较少.这正是酿造酱油与配制酱油风味不同的原因之一.该文研究结果验证了生产酿造酱油时不同原料不同工艺会对风味物质产生影响.     

Value-Added Production of Nisin from Soy Whey

The objective of this study was to evaluate the potential of low/negative value soy whey (SW) as an alternative, inexpensive fermentation substrate to culture Lactococcus lactis subsp. lactis for nisin production. Initially, a microtiter plate assay using a Bioscreen C Microbiology Plate Reader was used for rapid optimization of culture conditions. Various treatments were examined in efforts to optimize nisin production from SW, including different methods for SW sterilization, ultrasonication of soy flake slurries for possible nutrient release, comparison of diluted and undiluted SW, and supplementation of SW with nutrients. In subsequent flask-based experiments, dry bacterial mass and nisin yields obtained from SW were 2.18 g/L and 619 mg/L, respectively, as compared to 2.17 g/L and 672 mg/L from a complex medium, de Man–Rogosa–Sharpe broth. Ultrasonication of soybean flake slurries (10% solid content) in water prior to production of SW resulted in ∼2% increase in biomass yields and ∼1% decrease in nisin yields. Nutrient supplementation to SW resulted in ∼3% and ∼7% increase in cell and nisin yields, respectively. This proof-of-concept study demonstrates the potential for use of a low/negative value liquid waste stream from soybean processing for production of a high-value fermentation end product.     

Soy glycinin microcapsules by simple coacervation method

Encapsulation of a dispersed oil phase (hexadecane) was realized by simple coacervation method using soy glycinin as the wall forming material. Suitable emulsification and coacervation conditions, that favor the formation of microcapsules wall, were identified and investigated. Mild acid (pH 2.0) and heat (55 degrees C) treatments of the reaction medium during the emulsification step enhanced significantly the deposition of coacervated glycinin around oil droplets. A pronounced correlation between glycinin concentration in the continuous phase, specific surface of the dispersed phase and the microencapsulation efficiency was also observed. Coacervation step study concerned the morphology and the stability of microcapsules. Controlled initiation of the coacervation, by slow readjustment of the pH, allowed a homogeneous precipitation of glycinin around oil droplets as well as the absence of aggregation phenomena. Since the morphology of microcapsules was considerably affected by a prolonged stirring of the reaction medium, the coacervation and reticulation time were optimized in order to preserve the homogeneity of the microcapsules size distribution and the microencapsulation efficiency.     

酱油的分类与化学成分探究

酱油是用粮食原料酿造的液体调味品,红褐色,有独特酱香。酱油中含有许多化学物质,主要介绍酱油的分类与主要化学成分的基本知识。     

Chemical Modification of Soy Protein for Wood Adhesives

Mussel protein is a strong and water‐resistant adhesive, but is expensive and not readily available. Soy protein is inexpensive, abundant, and annually renewable, but suffers from low adhesive strengths and low water resistance of the bonded products. This study reveals that introducing a key functional group from the marine adhesive protein to soy protein converts the soy protein to a strong and water‐resistant wood adhesive.     

Rheological and Solubility Properties of Soy Protein Isolate

Soy protein isolate (SPI) powders often have poor water solubility, particularly at pH values close to neutral, which is an attribute that is an issue for its incorporation into complex nutritional systems. Therefore, the objective of this study was to improve SPI solubility while maintaining low viscosity. Thus, the intention was to examine the solubility and rheological properties of a commercial SPI powder at pH values of 2.0, 6.9, and 9.0, and determine if heat treatment at acidic or alkaline conditions might positively influence protein solubility, once re-adjusted back to pH 6.9. Adjusting the pH of SPI dispersions from pH 6.9 to 2.0 or 9.0 led to an increase in protein solubility with a concomitant increase in viscosity at 20 °C. Meanwhile, heat treatment at 90 °C significantly improved the solubility at all pH values and resulted in a decrease in viscosity in samples heated at pH 9.0. All SPI dispersions measured under low-amplitude rheological conditions showed elastic-like behaviour (i.e., G′ > G″), indicating a weak “gel-like” structure at frequencies less than 10 Hz. In summary, the physical properties of SPI can be manipulated through heat treatment under acidic or alkaline conditions when the protein subunits are dissociated, before re-adjusting to pH 6.9.     

气相色谱法测定大豆磷脂中磷脂酰肌醇

将含磷脂酰肌醇的大豆磷脂水解后,进行乙酰衍生化得到肌醇六乙酯,然后用气相色谱法测定肌醇六乙酯,从而计算出大豆磷脂中磷脂酰肌醇的含量。对一大豆磷脂试样,按提出方法测定6次,得磷脂酰肌醇含量的平均值为8.61 mg.g-1,测定结果的相对标准偏差为2.2%。又在此试样的基础上加入不同量的磷脂酰肌醇标准(10.0~110.0 mg)作回收试验,所得回收率结果为95.6%~104.2%。     

Enzymatic Hydrolysis of Soy Protein Isolates. DSC study

The aim of this work was to analyze the possible use of differential scanning calorimetry (DSC) as a method to study the process of protein modifications during enzymatic hydrolysis. Results of the enzymatic hydrolysis of soy protein showed significant differences in the values of maximum deflection temperature (T _p), heat of reaction (ΔH), and width at half peak height (ΔT _1/2), between DSC curves corresponding to the substrate, or zerotime of hydrolysis, and those of the hydrolysates obtained by the action of cucurbita and pomiferin enzymes. DSC curve changes mentioned were explained by the use of gel-filtration chromatography, denaturing electrophoresis and surface hydrophobicity of the hydrolysis products obtained at 30 min of reaction. This revised version was published online in August 2006 with corrections to the Cover Date.