HRP/L-Cys/Cu自组装膜对苯甲醛的电催化作用

本论文以Cu电极为基底,层层自组装L-半胱氨酸(L-Cys)和辣根过氧化物酶(HRP),形成HRP/L-Cys/Cu双层膜电极,并利用循环伏安法(CV)和交流阻抗法(EIS)研究了膜的致密度。在无H_2O_2存在的情况下,将HRP/L-Cys/Cu双层膜电极插入不同浓度的苯甲醛溶液中,有明显的电催化作用,即使苯甲醛浓度低至0.001 mol/L时依然有清晰的电流信号,这有利于苯甲醛的深度去除。同时发现pH对HRP/L-Cys/Cu电极处理苯甲醛有影响,最佳的电催化pH为6.0和8.0。     

模板法合成三维菊花状TiO2纳米花及其性能

为了解决一维、二维纳米材料在降解有机污染物时,易发生团聚、催化活性低、难以回收利用等问题,以TiO₂(P25)和NaOH为原料,ZnO为模板,采用水热法合成了三维菊花状TiO₂纳米花．运用扫描电子显微镜、X射线衍射仪、氮气吸附脱附、紫外-可见漫反射、傅立叶红外等手段对合成的样品进行测试分析. 结果表明:其花瓣是由TiO₂纳米颗粒通过自组装定向排列而成的链状结构,构成纳米花的粒子晶粒尺寸约15 nm,花状结构尺寸约为5 μm,结晶性良好,为锐钛矿相;比表面积为102.3 m²／g,平均孔径为17.41 nm;以亚甲基蓝为目标污染物,在紫外光照射下对其进行光催化性能实验,80 min亚甲基蓝的降解率为98％,催化活性高于P25,显示出较强的光催化活性．     

巯基三唑自组装膜修饰金电极对对苯二酚的电催化研究

实验采用自组装膜法将巯基三唑修饰在金电极上．结果表明：修饰后的金电极对对苯二酚产生明显的催化作用;扫描速率的平方根与对苯二酚氧化峰电流存在相关关系,表明对苯二酚的氧化还原反应受扩散控制;对苯二酚浓度与其氧化峰电流呈较好的线性关系,可以用来分析和检测该浓度范围内对苯二酚的含量．     

Frictional Responses of Octadecyltrichlorosilane (OTS) and 1H, 1H, 2H, 2H-Perfluorooctyltrichlorosilane (FOTS) Monolayers Self-assembled on Aluminium over Six Orders of Contact Length Scale

We have measured the frictional responses of two silane molecules (Octadecyltrichlorosilane; OTS and 1H, 1H, 2H, 2H-Perfluorooctyltrichlorosilane; FOTS) self-assembled on an aluminium substrate in their non heat-treated and heat-treated states. We varied the contact length scale by performing the experiments in atomic force microscope, nanotribometer and macro scale pin-on-disc machine. We have found that conformational disorder and molecular stiffness have major influences on friction in strongly distinguishing the response of OTS from that of the FOTS molecules. The frictional identity between the two molecules before and after heat treatment, though somewhat contrary to that suggested from purely surface energy considerations, is found to hold over six orders of contact length scales, ten orders of normal load and in three vastly different contact conditions; (a) the probe penetrates about 25% of the molecular backbone of a SAM; no substrate deformation, (b) the contact of the probe with the SAM is conformal and the substrate is plastically deformed and (c) the molecule is dispersed in 5% (v/v) concentration in n-hexadecane to lubricate a pin-on-disc contact.     

Characterization of mixed self-assembled monolayers for immobilization of streptavidin using chemical force microscopy

Mixed self-assembled monolayers (SAMs) to immobilize streptavidin on a gold surface were investigated by measuring the pull-off force between an AFM tip and a biotin-modified surface using CFM. Biotin-LC-NHS was modified on SAMs prepared from a mixed solution of cystamine and MEOH. Increased pull-off forces between the AFM tip and the surface were observed with an increased cystamine mole fraction in the solution. Streptavidin was immobilized onto biotin-LC-NHS modified mixed SAMs and analyzed by tapping AFM. Also, the formation of mixed SAMs containing MUOH and MBDA was confirmed using CFM. The measured pull-off forces on the only MBDA surface were larger than those on the surface with MUOH. These results can be applied to determine an optimal mixing ratio of MUOH and MBDA SAMs that reduces non-specific streptavidin binding onto a surface.     

Mechanical properties and tribological behavior of ZrO<Subscript>2</Subscript> thin films deposited on sulfonated self-assembled monolayer of 3-mercaptopropyl trimethoxysilane

A silane coupling reagent (3-mercaptopropyl)trimethoxysilane (abridged as MPTS) was self-assembled on a single-crystal Si substrate to form a two-dimensional organic monolayer (MPTS-SAM). The terminal –SH group in the MPTS-SAM film was in-situ oxidized to –SO₃H group to endow the film with good chemisorption ability. Then ZrO₂ thin films were deposited on the oxidized MPTS-SAM by way of the enhanced hydrolysis of aqueous zirconium sulfate (Zr(SO₄)₂·4H₂O) in the presence of aqueous HCl at 50 °C, making use of the chemisorption ability of the –SO₃H group. The thickness of the ZrO₂ films was determined with an ellipsometer, while their morphologies and corresponding friction forces were analyzed by means of atomic force microscopy. The hardness and elastic modulus of the ZrO₂ thin films were determined on a Nanoindentation II (MET) instrument. The macro-friction and wear behaviors of the ZrO₂ films sliding against an AISI-52100 steel ball were examined on a unidirectional friction and wear tester and the worn surface morphologies observed on a scanning electron microscope (SEM). As the results, the as-deposited ZrO₂ thin film at a deposition duration of 100 h is about 100 nm thick, it decreases to 48 nm after annealing at 500 °C and further decreases to 45 nm after heating at 800 °C. The as-deposited ZrO₂ film is relatively rougher, with the rms to be about 1.0 nm, while the ZrO₂ thin films heated at 500 and 800 °C have surface roughness rms of 0.76 nm and 0.68 nm, respectively. The ZrO₂ film annealed at 800 °C has a high hardness to elastic modulus (H/E) ratio (0.062) as compared to the as-deposited ZrO₂ film and the film annealed at 500 °C. Both the two annealed ZrO₂ films show excellent wear-resistance as they slide against AISI-52100 steel at a normal load below 2.0 N, while the one annealed at 800 °C has better wear-resistance. The differences in the friction and wear behaviors of the as-deposited ZrO₂ film, the ZrO₂ film annealed at 500 °C and that annealed at 800 °C are attributed to their different micro structures and compositions. Since the ZrO₂ films was well adhered to the underlying MPTS-SAM, it might find promising application in the surface-protection of single crystal Si and SiC subject to sliding at small normal load in microelectromechanical systems (MEMS).     

A Novel Method to Remove Self-Assembled Monolayer of Porphyrin from the Gold Surface by Cyclic Voltammetry

Abstract

Cyclic voltammetry, a traditional technique used in self-assembled monolayer practice, was employed to explore the possibility of removing a very adherent self-assembled monolayer of 5-[4-(3-Mercaptopropyloxyphenyl)]-10,15,20-phenylporphyrin from a gold electrode surface. The phenylporphyrin monolayer was gradually removed and the gold electrode surface cleaned electrochemically, in strong alkaline electrolytes, using cyclic voltammetry at negative potentials. The results proved to be better than that obtained using mechanical polishing.     

Preparation of hierarchical mesoporous CaCO3 by a facile binary solvent approach as anticancer drug carrier for etoposide

To develop a nontoxic system for targeting therapy, a new highly ordered hierarchical mesoporous calcium carbonate nanospheres (CCNSs) as small drug carriers has been synthesized by a mild and facile binary solvent approach under the normal temperature and pressure. The hierarchical structure by multistage self-assembled strategy was confirmed by TEM and SEM, and a possible formation process was proposed. Due to the large fraction of voids inside the nanospheres which provides space for physical absorption, the CCNSs can stably encapsulate the anticancer drug etoposide with the drug loading efficiency as high as 39.7 wt.%, and etoposide-loaded CCNS (ECCNS) nanoparticles can dispersed well in the cell culture. Besides, the drug release behavior investigated at three different pH values showed that the release of etoposide from CCNSs was pH-sensitive. MTT assay showed that compared with free etoposide, ECCNSs exhibited a higher cell inhibition ratio against SGC-7901 cells and also decreased the toxicity of etoposide to HEK 293 T cells. The CLSM image showed that ECCNSs exhibited a high efficiency of intracellular delivery, especially in nuclear invasion. The apoptosis test revealed that etoposide entrapped in CCNSs could enhance the delivery efficiencies of drug to achieve an improved inhibition effect on cell growth. These results clearly implied that the CCNSs are a promising drug delivery system for etoposide in cancer therapy.     

基于芘丁酸的SAMs薄膜制备及荧光氧猝灭特性

利用SAMs(self-assembled monolayers)技术将芘丁酸分子接枝于经过3-氨丙基三乙氧基硅烷分子(APTES)修饰的玻璃基片表面。通过XPS、荧光发射光谱的表征以及接触角测试等来考察薄膜的结构及性能,考察了薄膜在不同溶剂中的荧光氧猝灭特性。实验表明,芘丁酸分子以化学键合的方式固定于玻片表面,形成了SAMs薄膜,其在甲苯、三氯甲烷、二氯甲烷等极性较小的有机溶剂中的氧猝灭效率较高,并具有良好的重复性。     

Self-assembled liquid crystalline nanoparticles as an ophthalmic drug delivery system. Part I: influence of process parameters on their preparation studied by experimental design

To develop self-assembled liquid crystalline nanoparticles as a drug delivery system for keratoconus treatment, a formulation containing riboflavin a water-soluble drug, two surfactants (poloxamer 407 and mono acyl glycerol – monoolein-) and water was optimized and prepared by emulsification and a homogenization process. A fractional factorial design was applied to estimate the main effects and interaction effects of five parameters on two responses, namely particle size and encapsulation efficiency. The five parameters are the temperature of the two phases, the duration of emulsification, the presence of heating during homogenization, the number of passes and pressure. The most influent parameters are the presence of heating during the homogenization and the pressure that led to the production of nanoparticles with an average size of 145?nm and an average encapsulation efficiency of 46%.