水溶性小麦醇溶蛋白纳米粒子的制备及表征

以来源广泛的小麦醇溶蛋白(gliadin)为原料,食品级的酪蛋白酸钠(SC)为静电和空间稳定剂,利用反溶剂过程中小麦醇溶蛋白的自组装行为制备了水溶性小麦醇溶蛋白纳米粒子(Gliadin/SC纳米粒子)。研究了其形成过程及微结构,揭示了gliadin与SC的比例、pH值、离子强度等因素对gliadin/SC纳米粒子粒度、电位及稳定性的影响规律。结果显示,Gliadin/SC纳米粒子为球形,粒径在190~310 nm之间,Zeta电位在中性条件下-28.6~-32.8mV其悬浮液(PG-SC)呈半透明状,2周未出现失稳现象。Gliadin/SC纳米粒子受pH值的影响显著,对盐离子敏感。PG-SC冻干后能够复溶,且粒径和多分散性无太多改变。水溶性Gliadin/SC纳米粒子具有对疏水性生物活性物质的荷载和输送的潜在应用价值。     

丁香酚/玉米醇溶蛋白纳米粒子膜的制备及表征

采用反溶剂法构建了丁香酚/玉米醇溶蛋白纳米粒子体系,并将荷载丁香酚的玉米醇溶蛋白纳米粒子制备成纳米粒子膜。以膜的厚度、透光率、机械性能、白度、水蒸气透过系数和透油系数为指标,确定最佳制备工艺条件,并对该条件下制备的产品的抗菌性质进行测定。制得的丁香酚/玉米醇溶蛋白纳米粒子粒径在255~390nm,且具有较好分散度。最佳制膜条件为:玉米醇溶蛋白和80%乙醇固液比为1∶10(g/ml)、甘油质量分数为20%、丁香酚质量浓度为20μg/ml。该条件下制备的产品为淡黄色,较薄,无异味,有较好的机械性能,抗菌性较好。     

小麦醇溶蛋白自组装纳米粒子负载白藜芦醇的性质研究

小麦醇溶蛋白是谷朊粉的主要成分之一,用小麦醇溶蛋白包埋白藜芦醇以达到稳定白藜芦醇的目的。用反溶剂法制得其自组装纳米粒子,对乙醇浓度、蛋白浓度、分散液pH、分散液盐浓度等因素对纳米粒子的粒径以及Zeta电位的影响做出了探究。发现在乙醇浓度为65%,蛋白质浓度4%,分散液pH为4.5,分散液盐浓度为0.00 mol/L时,得到理想的纳米粒子,其粒径约为(185.1±8.5)nm,Zeta电位为(19.36±1.03)m V。而后在最佳条件下用小麦醇溶蛋白纳米粒子负载白藜芦醇,发现该复合物在芯壁比为1∶40时包埋率最高,此时粒径(166.7±3.7)nm,Zeta电位(15.68±0.74)m V,包埋率为55.0%,载药率为1.5%。小麦醇溶蛋白纳米粒子可以用来稳定白藜芦醇。     

用于PET的纳米粒子添加剂

人们对于纳米粒子的构成一直存在着很多的争议和误解。一些人只是以纳米(nm)为尺度来描述他们的产品，比如：将2μm的粒子说成2000nm的粒子。其实仅用一个尺寸指标很难对纳米粒子进行准确定义。     

新型抗菌丝绸壁纸制备及其性能检测

采用硫酸法从微晶纤维素中制得纤维素纳米晶,并结合简单沉淀法制得纳米氧化锌/纤维素纳米晶复合粒子。通过简单热轧工艺将复合粒子有机嵌入基纸和丝绸面料之间,制备出抗菌丝绸壁纸。通过对复合粒子与抗菌丝绸壁纸的结构表征与性能测试。实验结果表明:平均粒径为37nm的氧化锌负载在纤维素纳米晶骨架上;同时在383nm处存在紫外光吸收峰,进一步证实复合粒子中含有纳米氧化锌,且成功负载在丝绸壁纸表面;所制备的抗菌丝绸壁纸具有优良的抗菌效果及耐洗涤性能,经50次循环洗涤后,其对大肠杆菌和金黄葡萄球菌的抑菌率均可高达99%以上。     

稻壳更有价值的出路--制备混凝土顶级掺合料

从资源利用和物料平衡的观点看，稻壳最适宜的出路是制备用作混凝土掺合料的纳米SiO2。实验表明，将稻壳控制在600℃焚烧，所得的低温稻壳灰(LowTemperature—Rice Husk Ash ,L-RHA)由纳米尺度的SiO2粒子(约50nm)疏松地粘聚而成。稻壳灰结构中除了以往报道过的微米尺度的蜂窝孔外，还含有大量由SiO2粒子非紧密粘聚而形成的纳米尺度孔隙(＜50nm)。纳米尺度的SiO2粒子和纳米尺度的孔隙是低温稻壳灰具有巨大的比表面积和超高火山灰活性的根本原因。活性试验显示，低温稻壳灰火山灰活性超过造粒硅灰，对普通混凝土和高强混凝土都具有强烈的增强作用。当低温稻壳灰替代水泥量为10％—20％时，可提高高强混凝土抗压强度10Mpa以上。     

负载小麦醇溶蛋白纳米银胶体颗粒的抗菌壳聚糖复合膜构建及表征

本研究采用浇筑法,成功构建了Ag NPs/小麦醇溶蛋白/壳聚糖复合抑菌膜,实现了Ag NPs的稳态化和协同增效。自组装的小麦醇溶蛋白(gliadin),同时充当AgNPs的螯合剂和稳定剂,有效抑制了纳米银颗粒(AgNPs)团聚。与其他复合膜相比,gliadin/Ag NPs复合膜透明度良好。SEM和EDS证实Ag NPs均匀分布于复合膜。此外,gliadin/AgNPs复合颗粒具有优异的缓释特性。人皮肤成纤维细胞评估结果表明复合膜具有更好的生物相容性,激光共聚焦显微镜(CLSM)显示gliadin/Ag NPs复合膜对大肠杆菌与金黄色葡萄球菌具有更强的抗菌效果。这些薄膜在抗菌食品包装材料、伤口敷料以及植入物的开发方面极具应用价值。     

复合空心纳米粒子PAA@Fe_3O_4的制备及药物控释研究

在反尖晶石型空心磁性Fe3O4纳米粒子表面修饰上APTES,然后通过化学交联法包覆上聚丙烯酸(PAA)制备了p H敏感性PAA@Fe3O4复合空心纳米粒子。用透射电子显微镜(TEM)、振动样品磁强计(VSM)、纳米粒度仪、傅里叶变换红外光谱仪和紫外分光光度计对包覆前后的形貌、结构、磁性和包覆率进行表征。并用罗丹明6G(R6G)作为模拟药物进行药物负载和释放性能进行体外实验研究。结果表明,所制备的PAA@Fe3O4复合粒子具有良好的磁学性能,负载药物为1011 mg/g。复合磁粒上的R6G药物释放的最大释放比达到93.0%,这种药物控释属于一级释放曲线,同时探讨了基于分子溶解度的可能机理。这种基于磁性纳米粒子和高分子材料的复合药物负载体系,有助于提高药物的靶向递送性能并改善诊疗效率。     

科学家将壳聚糖、有机酸及其纳米级胶体用于食品抗菌包装材料

据sciencedirect数据库消息,2013年6月《食品控制》(Food Control)刊登一项壳聚糖、有机酸及其纳米级胶体在食品抗菌包装材料中潜在应用的研究。研究人员将低分子量及中分子量的壳聚糖及有机酸(苯甲酸、山梨酸、纳米级苯甲酸-山梨酸胶体)抗菌活性进行对比。研究结果表明,壳聚糖抗菌活性受其分子量的影响,低分子量及中分子量壳聚糖最低抑菌浓度(w/v)分别为0.010%、0.015%,纳米级苯甲酸-山梨酸胶体抗菌活性显著高于其非纳米级胶体。纳米级胶体抗菌剂可以使用更少的抗菌物质达     

尾巨桉微/纳米粒子溶出规律的研究

采用单因素实验法,分析了尾巨桉新鲜木片与陈旧木片的溶出粒子特征及其微/纳米粒子在常规溶剂抽提和超声波、冷冻、微波预处理抽提中的溶出规律.结果表明,常规溶剂抽提时,新鲜木片溶出的纳米粒子(粒径<100 nm)在体积和粒子数上大于陈旧木片,而大于91.3 nm的粒子在体积和粒子数上小于陈旧木片;随着抽提时间的延长,尾巨桉新旧木片中抽提物的溶出量均呈增加趋势.超声波、冷冻与微波预处理可降低尾巨桉新旧木片溶出粒子的集聚程度,提高抽提物溶出量,其中超声波预处理的作用最为明显.     

基于上转换纳米颗粒和金纳米颗粒的Cd2+免疫检测新方法

基于上转换纳米颗粒(UCNPs)和金纳米颗粒(AuNPs)间的荧光共振能量转移(FRET)和抗原抗体的识别作用构建了Cd~(2+)的免疫检测平台。制备水溶性UCNPs表面修饰Cd-抗原作为能量供体探针,同时在AuNPs表面修饰Cd-抗体作为能量受体探针。抗原-抗体的免疫结合使得UCNPs和AuNPs发生FRET过程,引起UCNPs荧光猝灭;当检测体系中存在Cd~(2+)时,Cd~(2+)与UCNPs-抗原竞争性地结合AuNPs-抗体,从而抑制了FRET过程,荧光信号值随着Cd~(2+)质量浓度的增加而增加。结果表明,该方法检测范围为0.01～10 ng/mL,检出限可达0.01 ng/mL。将该方法应用于自来水样品中Cd~(2+)的检测,当加标水平为0.1、1、10 ng/mL时,回收率为98%～109%,相对标准偏差为3.4%～4.1%。     

基于上转换纳米粒子与金纳米粒子构建荧光共振能量转移体系检测双酚A方法研究

制备了粒径为13nm的金纳米粒子,在其表面修饰双酚A(BPA)适配体作为能量受体探针;并利用聚丙烯酸(PAA)包覆油溶性的上转换荧光纳米材料(UCNPs)制备水溶性的UCNPs,在其表面修饰适配体互补链形成功能化UCNPs作为能量供体,构建了基于FRET原理的BPA生物传感检测平台。结果表明:该检测体系在1×10~(-9)～1×10~(-3) mol/L时具有良好的线性关系(R~2=0.992 3),检出限低至1×10~(-10) mol/L。     

Preparation of water-soluble antimicrobial zein nanoparticles by a modified antisolvent approach and their characterization

We developed a simple antisolvent procedure to prepare core/shell zein/SC nanoparticles by directly pouring sodium caseinate (SC) into zein solutions. The nanoparticles are spherical in shape, possessing the re-dispersibility in de-ionized water after freeze-drying. The nanoparticles possessed strong loading capacity for thymol, and were stable over 8 months storage. Morphological attributes, antimicrobial and antioxidant properties as well as release profiles of thymol-loaded nanoparticles were investigated. Thymol loadings gave the nanoparticles antimicrobial activity against tested bacteria on agar diffusion assay as well as DPPH radical scavenging activity, in a dose-dependent manner. These nanoparticles were also effective in delaying the growth of Staphylococcus aureus in fresh M–H broth at 37 °C. Thymol loading resulted in a slight increase in particle size, and did not affect the re-dispersibility of the nanoparticles. The nanoparticle sustained the release of thymol, and the release kinetic of thymol can be described as a two-step biphasic process.     

新型脂质体的研究进展

作为药物传递系统的载体,纳米脂质体、柔性脂质体、多糖包覆脂质体等新型脂质体的研究已取得显著进展,现将最新进展进行综述,关注的焦点是脂质体的稳定性、生物粘附性、耐酶性以及在血循环中的长循环性、隐形性、立体稳定性、控释性、靶向性,以提高药物的生物利用度。同时对作为第二代脂质体的固体脂质纳米粒作了简要的论述。     

Flavonoids: precipitation kinetics and interaction with surfactant micelles

Polyphenolic substances, such as flavonoids, attract considerable interest due to their ability to act as antioxidants. The vast majority of studies published deal with the nutritional, biochemical, or chemical structure aspects of these substances while few reports exist on the physico-chemical properties as well as solution behavior of the substances. In this article we report on the precipitation kinetics of naringenin, quercetin, and rutin in pure water as well as in micellar solutions of Tween 80. The methods used are dynamic and static light scattering in conjunction with cryo transmission electron microscopy. The results show that the substances precipitate rapidly in pure water. In the presence of Tween 80 micelles, however, the flavonoids can become solubilized in the micelles, which can result in solutions which are stable for days. The results suggest that the extent of solubilization is related to the chemical structure of the flavonoids. This study illustrates that precipitation kinetics and the distribution of polyphenolic substances in solutions and dispersions are factors of importance, which should be taken into account when designing investigations and interpreting results.     

A novel electrochemical immunosensor based on Fe3O4@graphene nanocomposite modified glassy carbon electrode for rapid detection of Salmonella in milk

Foods contaminated by foodborne pathogens have always been a great threat to human life. Herein, we constructed an electrochemical immunosensor for Salmonella detection by using a Fe₃O₄@graphene modified electrode. Because of the excellent electrical conductivity and mechanical stability of graphene and the large specific surface area of Fe₃O₄, the Fe₃O₄@graphene nanocomposite exhibits an excellent electrical signal, which greatly increased the sensitivity of the immunosensor. Gold nanoparticles were deposited on Fe₃O₄@graphene nanocomposite by electrochemical technology for the immobilization of the antibody. Cyclic voltammetry was selected to electrochemically characterize the construction process of immunosensors. The microstructure and morphology of related nanocomposites were analyzed by scanning electron microscopy. Under optimized experimental conditions, a good linear relationship was achieved in the Salmonella concentration range of 2.4 × 10² to 2.4 × 10⁷ cfu/mL, and the limit of detection of the immunosensor was 2.4 × 10² cfu/mL. Additionally, the constructed immunosensor exhibited acceptable selectivity, reproducibility, and stability and provides a new reference for detecting pathogenic bacteria in milk.     

汤的威力:食品科学新知

汤在各国的饮食文化中都带有健康调理的色彩,现代临床医学和药效学也验证了部分汤的功效.本文简要回顾了有关汤中存在的纳米颗粒在形成、组成成分和活性实验上的研究结果,展望了汤纳米颗粒的研究能给功效成分筛选和毒理学研究带来的新思路.     

Gelatin-templated gold nanoparticles as novel time-temperature indicator

Gold nanoparticles (AuNPs) were generated by mixing of gelatin solution and gold precursor (HAuCl(4,) 1 mM) under isothermal condition (80 °C). The effects of gelatin concentration (1% to 6%) and pH (3, 5, and 9) on the color signal of gelatin-templated AuNPs were examined. The λ(max) of AuNPs shifted from 535 to 552 nm at 1% gelatin, and the color intensity of the AuNPs was a maximum at 2% gelatin. The speed of color development was accelerated at pH 3, and the AuNPs prepared at pH 3 were bigger (45 to 162 nm) and more irregular in shape than those prepared at pH 5 or 9. When the performance of gelatin nanoreactor as time-temperature indicator (2%, pH 5) was evaluated in a simulated frozen storage, clear color signals developed as little as 6 h of exposure at 30 °C and the intensity of the color signal was proportional to duration of exposure. Practical Application: Gelatin-gold precursor mixture acted as a "nanoreactor" for gold nanoparticle synthesis without need for any additional reactants. When the gelatin-templated AuNPs were exposed to 30 °C, color signals developed with intensities that depended on the duration of exposure. The reaction was irreversible and colors were easily discerned by the naked eye.     

木质素纳米颗粒制备及其在水凝胶材料中的应用研究进展

木质素作为可再生天然芳香性高分子生物质资源受到人们越来越多的关注,对木质素高值化利用的研究在不断深入。木质素纳米颗粒（LNP）的制备与应用是实现木质素高值化利用的有效途径,木质素具有环境和生物相容性好、价格低廉且资源丰富等优点,但其固有的异质性、颗粒尺寸较大和分散性差的问题阻碍其应用,木质素纳米化可实现颗粒尺寸大小和形态的可控,LNP的比表面积和表面功能位点增加,相比原始木质素,抗氧化、抗紫外线等能力得到进一步增强,具有广泛的应用前景。本文对LNP的制备以及在水凝胶材料中的应用进行了综述,并对未来发展进行了展望。     

Characterization of glucoamylase immobilized on magnetic nanoparticles

Magnetic support was prepared by precipitation from an alkaline solution of divalent and trivalent iron ions and subsequently was modified with 3‐aminopropyltriethoxysilane. FTIR analysis showed existence of a new Si–O–Fe bond in obtained particles. Scanning electronic microscopy images shows that the nanoparticles of all samples have particle size below 30 nm. Glucoamylase AMG 300L was immobilized onto the modified magnetic support using glutaraldehyde as a coupling agent. Obtained preparations had specific activity of 148 U/g of the support when measured at 55°C using maltose as substrate. The immobilized enzyme exhibited mass transfer limitation as reflected by a higher apparent K_m value and a lower energy of activation. The immobilization was almost completely terminated after 30 min of the reaction at 30°C. The highest immobilization yield of the enzyme was achieved at glutaraldehyde concentration of 10 mM. The immobilization did not influence considerably on optimum pH and temperature of substrate hydrolysis catalyzed by investigated enzyme (55°C, pH 4.5). Moreover, immobilized glucoamylase was easily separated from the reaction medium by an external magnetic field and retained about 60% of initial activity after nine repeated cycles of enzyme reaction followed by magnetic separation.