高压静电法制备载阿糖胞苷海藻酸钙-几丁聚糖微胶囊

采用海藻硅酸钠和几丁聚糖为原料制备海藻酸钙-几丁聚糖药物缓释微胶囊,初步考察了载阿糖胞苷微胶囊的制备以及不同分子量几丁聚糖、静/动态载药方式对阿糖胞苷释放性能的影响。     

海藻酸钙微胶囊的制备

研究了海藻酸钙微胶囊的制备条件和影响因素。试验结果表明 :海藻酸钠浓度不宜超过 3.0 % ,Ca Cl2的浓度为 1.0 %～ 4 .0 % ,适宜转速为 30 0 r· min- 1 ,下滴速率可控制在 6 0～ 90滴· m in- 1 ,成型的微胶囊浸泡在蒸馏水中存放 30 d后变化不大     

高载药量海藻酸钙/几丁聚糖微胶囊的性能

采用乳化固化法制备了平均粒径为820nm海藻酸钙微球,并制备了海藻酸钙/几丁聚糖微胶囊。以牛血清白蛋白(BSA)为模型药物,考察投药浓度、几丁聚糖分子量和浓度等对微胶囊载药量和药物释放的影响,发现其载药量最大可达40%以上,结果还显示这种微胶囊具有很好的体外缓释性能。     

纳米微粒zno表面修饰方法的研究

综述了纳米微粒ZnO表面修饰的方法,并对各种修饰方法及其特点、修饰机理进行了分析和归纳。     

直接从水玻璃合成表面修饰的纳米SiO2微粒

采用溶胶-凝胶法,以水玻璃为原料,在加入复合表面活性剂和分散剂的条件下,与乙酸反应直接得到纳米表面修饰的SiO2微粒。TEM照片显示,纳米SiO2颗粒为球形,粒度为10～30nm,统计平均粒径为20nm。合成工艺研究表明,纳米SiO2粒度大小和分散度大小可由表面活性剂浓度、反应物浓度、分散剂浓度和反应温度等控制,其中表面活性剂浓度、反应物浓度、分散剂浓度、反应温度的最佳值分别为：0．6mmol／L,0．6mol／L,7mmol／L,55℃。     

吸水性微胶囊界面修饰提高水泥基材料抗渗性研究

在自修复水泥基材料中,微胶囊与水泥基体间的界面结合决定着微胶囊被裂缝触发的概率,从而影响自修复效果。本文针对吸水性微胶囊的界面结合问题,利用硅烷偶联剂KH550修饰环氧/海藻酸钙微胶囊表面,以改善其与水泥基体间的界面结合情况。采用X射线光电子能谱仪、电感耦合等离子体发射光谱仪等表征硅烷偶联剂在微胶囊表面的键合状况,利用压汞法分析水泥基材料的孔结构,并测试水泥基材料的抗渗性与自修复效果。结果表明,硅烷偶联剂能够与微胶囊外壁的海藻酸钙发生化学键合,微胶囊与水泥基体间的界面结合得到有效改善,水泥基体中有害孔数量减少,无害孔和少害孔数量增加,水泥基材料的抗渗性和自修复效果获得提升。     

纳米金修饰电极的电化学研究

将由柠檬酸三钠与氯金酸制备的纳米金颗粒利用自组装方法修饰于金电极表面形成纳米金修饰电极,运用N5粒度测定仪、透射电子显微镜（TEM）和原子力显微镜（AFM）对纳米颗粒及其修饰电极进行了表征。利用循环伏安法（CV）与交流阻抗法（EIS）研究了纳米金修饰电极的电化学性质。     

纳米微胶囊技术与纳米化妆品研究进展

本文着重阐述了有关纳米胶囊的制备方法及最新研究进展,并展望了纳米技术及纳米微胶囊在化妆品领域的应用前景.     

直接从水玻璃合成表面修饰的纳米SiO2微粒

采用溶胶-凝胶法，以水玻璃为原料，在加入复合表面活性剂和分数剂的条件下，与乙酸反应直接得到纳米表面修饰的SiO2微粒。TEM照片显示，纳米SiO2颗粒为球形，粒度为10-30nm，统计平均粒径为20nm。     

几丁聚糖纳米颗粒的动态光散射研究

利用离子凝胶法制备几丁聚糖纳米颗粒,并用动态光散射测量所得颗粒的粒径分布与界面电位。研究结果发现,随着CS/TPP比值的减小,几丁聚糖纳米颗粒的粒径由单峰分布转变为双峰分布,说明三聚磷酸钠含量的增加会使几丁聚糖纳米颗粒之间产生聚集效应。界面电位值随着CS/TPP比值的减小而逐渐下降,原因是三聚磷酸钠浓度的增加使几丁聚糖纳米颗粒表面上更多的NH3+离子与三聚磷酸根离子反应中和的缘故。     

Immobilization of glucose oxidase in alginate-chitosan microcapsules

In order to improve its stability and catalytic rate in flour, the immobilization of glucose oxidase (GOX) was investigated in this work. The enzyme was encapsulated in calcium alginate-chitosan microspheres (CACM) using an emulsification-internal gelation-GOX adsorption-chitosan coating method. The interaction between alginate and chitosan was confirmed by infrared spectroscopy (IR). The resultant CACM in wet state, whose morphology was investigated by scanning electron microscopy (SEM), was spherical with a mean diameter of about 26 μm. The GOX load, encapsulation efficiency and activity of the CACM-GOX were influenced by concentration of chitosan, encapsulation time and encapsulation pH. The highest total enzymatic activity and encapsulation efficiency was achieved when the pH of the adsorption medium was near the isoelectric point (pI) of GOX, approximately pH 4.0. In addition, the molecular weight of chitosan also evidently influenced the encapsulation efficiency. Storage stabilities of GOX samples were investigated continuously over two months and the retained activity of CACM-GOX was 70.4%, markedly higher than the 7.5% of free enzyme. The results reveal the great potential of CACM-GOX as a flour improver.     

pH-responsive release from polypeptide microcapsules

Microcapsules were prepared from [Glu(OMe)]_m(Sar)_n (m = 21, n = 19) and [Lys(Z)]_m(Sar)_n (m = 27, n = 15), and were chemically modified to obtain a pH-responsive releasing membranes. One membrane was prepared by partially deprotecting the ester groups of [Glu(OMe)]_m(Sar)_n. The other membrane was prepared by connecting of poly(Glu) to side chain amino groups that were generated by a partial deprotection of [Lys(Z)]_m (Sar)_n. Consequently, two types of polypeptidic microcapsules were prepared; Glu residues in the main chain, and Glu residues in the graft chains on the positively charged main chain. Both microcapsules showed pH-responsive release of FITC-dextran encapsulated in the microcapsules. The release rate became slower in the medium at pH 3.0 than pH 7.5. Optical microscope observation revealed that partially deblocked [Glu(OMe)]_m(Sar)_n microcapsules swelled more at pH 7.5 than at pH 3.0; hence, enhanced permeation through the polypeptide membrane at pH 7.5. However, the shape of poly(Glu)-grafted [Lys(Z)]_m(Sar)_n microcapsules changed a little by changing pH of the medium. It is suggested that ion-pairing between carboxylate groups of poly(Glu) and ammonium groups of Lys acts as crosslinking to give the shape stability. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 453–458, 1997     

Synthesis of gold nanoparticles in hyperbranched polyol dispersions

In this study, a series of different generation hyperbranched poly(amine‐ester) with hydroxyl as terminal group were synthesized and used as protectants to synthesize gold nanoparticles with a facile and highly reproducible method. The effect of hyperbranched poly(amine‐ester) generation on size and their distribution of gold nanopartciels were discussed. The results of ultraviolet visible absorption spectroscopy, Transmission electron microscopy and scanning electron microscopy showed that the mean diameter were 24.3 ± 2.6 nm, 18.2 ± 2.1 nm, and 13.6 ± 1.5 nm corresponding to the different generation hyperbranched poly(amine‐ester), and the synthesized gold nanoparticles were almost monodisperse with a narrow size distribution. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Chemical,biological, and antibacterial characterization of silica glass containing silver and gold nanoparticles

The aim of this study has been the preparation of sol‐gel glasses with potential antibacterial properties. Bioactive glasses containing different percentages of silver and gold nanoparticles have been synthesized via the sol‐gel method. The obtained glasses have 0.5, 1, 1.5, and 2 wt% silver as well as a constant amount of gold nanoparticles (AuNP) added as colloidal solution (15 wt%). Fourier Transform Infrared (FTIR) spectroscopy was used to characterize the materials. Scanning electron microscopy (SEM) has been used to investigate the surface of each sample. Moreover, the materials have been characterized in order to verify their antibacterial activities as well as their bioactivity and cytocompatibility as a function of Ag and Au content. SEM/EDX analysis has shown that the samples are bioactive because they are able to stimulate hydroxyapatite nucleation on their surface when soaked in a simulated body fluid (SBF). WST‐8 assay of 3T3 cells, placed in contact with the material extracts, has showed that the glass does not induce cytotoxicity. Staphylococcus epidermidis and Pseudomonas aeruginosa strains have been used for the evaluation of the antibacterial properties of each sample. The experimental data have shown that all synthesized materials have antibacterial activity. However, the two bacterial strains respond differently to the materials. The data show that the presence of AuNP causes a decrease in the antibacterial activity of Ag⁺ ions.     

Oil adsorption ability of Miscanthus floridulus leaves determined using gold nanoparticles

ABSTRACT

This study was to demonstrate the possibility of using Miscanthus floridulus leaves to adsorb oils. The oil adsorption ability of Miscanthus leaves was approximately 3.59 ± 0.19 and 3.91 ± 0.15 (g oil/g leaves) for soybean oil and motor oil, respectively. The adsorption ability of Miscanthus leaves was directly visualized by scanning electron microscope (SEM) and transmission electron microscop (TEM) using gold nanoparticles that were adsorbed on the surface and edge of M. floridulus leaves. Changes in IR absorbance were used to exhibit specific interactions and the adsorption ability of M. floridulus leaves. The results showed M. floridulus leaves have hydrophobic structure on the leaf surface.     

Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

The citrate reduction method for the synthesis of gold nanoparticles (GNPs) has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM) via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.     

金纳米分光光度法测定尿中痕量鸟苷

在pH 3.6的BR缓冲溶液中,鸟苷与金纳米间相互作用,可降低金纳米粒子表面之间的静电斥力,从而改变溶液的吸光度。当鸟苷的浓度在1.75×10^-8-6.27×10^-6mol/L时,与体系ΔA630/A530形成良好的线性关系,其回归方程为：ΔA630/A530=1.33c×10^-6mol/L＋0.017 5,相关系数r=0.997。检出限为5.26×10^-9mol/L。相对标准偏差（RSD）为1.97%-3.26%,回收率为96.2%-98.9%。该法具有操作简单、快速、灵敏度高的优点。     

Separation of biosynthesized gold nanoparticles by density gradient centrifugation

The electronic, optical, magnetic, and catalytic properties of noble metal nanoparticles (NPs) strongly depend on their size. The size control of the noble metal NPs is one of the significant issues in the field of nanotechnology. We demonstrate both theoretically and experimentally that gold NPs can be separated by density gradient centrifugation (DGC) according to their size. By analyzing the force balance in a centrifuge with a horizontal rotor, a model was developed that relates the sedimentation shift to the centrifugation time and can be used to predict the effect of separation by the shift of particles within a specific period of time. The influences of centrifugation time and centrifugal force on the separation effect of DGC were evaluated.     

Microwave irradiation synthesis and self-assembly of alkylamine-stabilized gold nanoparticles

The hydrophobic gold nanoparticles protected with octadecylamine, tetradecylamine and decylamine, respectively, were prepared by using ethanol reduction in reverse micelle through microwave dielectric heating. In this experiment, the commonly used toxic and highly volatile organic solvents such as chloroform, toluene and so on, which were an obstacle for preparing hydrophobic nanoparticles under microwave irradiation, were replaced by a safe organic mixed solvent n-heptane/ethanol used as an oil phase. The various alkylamine-stabilized gold nanoparticles obtained through this method were characterized and analyzed by ultraviolet visible spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and elemental analysis. When the molar ratio of alkylamine to HAuCl₄ was 40 : 1, the average diameters and standard deviations for octadecylamine-, tetradecylamine- and decylamine-capped gold nanoparticles were 4.53 ± 0.79, 5.22 ± 1.66, and 4.09 ± 1.22 nm, respectively. Furthermore, the composition of octadecylamine-stabilized gold nanoparticles was determined to be (C₁₈H₃₇NH₂)₂₆₅·Au₂₈₂₂, and the experimental result showed that both the monodispersity and stability of these gold nanoparticles were beneficial to forming large areas of ordered two-dimensional arrangement at the air/water interface.     

Analysis of the contrast in icosahedral gold nanoparticles

When observing nanoparticles with the transmission electron microscope very often we observe a contrast that can be interpreted at first sight as coming from a some kind of a quasicrystalline array, i.e. with order but not periodicity. In the case of icosahedral particles their structure has been well studied by many years and their contrast explained in terms of twins. In this work we present the analysis of the quasi-periodic contrast observed in icosahedral gold nanoparticles along the five-fold direction, which resembles the contrasts of a quasicrystalline structures. A detailed analysis led us to demonstrate that it could correspond to a Moiré-pattern artifact produced in an array of Mackay icosahedra. Dedicated to Professor Konrad Hayek.