One step gold (bio)functionalisation based on CS2-amine reaction

Dithiocarbamates have been regarded as alternative anchor groups to thiols on gold surfaces, and claimed to be formed in situ through the reaction between secondary amines and carbon disulphide. In this paper, we further exploit this methodology for a convenient one step biomolecule immobilisation onto gold surfaces. First, the reactivity between CS₂ and electroactive compounds containing amines, primary (dopamine), secondary (epinephrine), and an amino acid (tryptophan) has been investigated by electrochemical methods. Cyclic voltammetric characterisation of the modified electrodes confirmed the immobilisation of all the target compounds, allowing the estimation of their surface concentration. The best result was obtained with epinephrine, a secondary amine, for which a typical quasi-reversible behaviour of surface confined electroactive species could be clearly depicted. Electrochemical reductive desorption studies enabled to infer on the extent of the reaction and on the relative stability of the generated monolayers. Bio-functionalisation studies have been accomplished through the reaction of CS₂ with glucose oxidase in aqueous medium, and the catalytic activity of the immobilised enzyme was evaluated towards glucose, by electrochemical methods in the presence of a redox mediator. Scanning tunnelling microscopy (STM) and Atomic force microscopy (AFM) were used respectively, to characterize the gold electrodes and Glucose Oxidase coverage and distribution on the modified surfaces.     

Self-assembled monolayers of alkanethiols on gold: the adsorption and wetting properties of monolayers derived from two components with alkane chains of different lengths

This paper describes the preparation and wetting properties of two-component self-assembled monolayers (SAMs) obtained by the competitive adsorption of one short-chain (HS(CH₂)₁₀Sh) and one long-chain (HS(CH₂)₂₁Lg) alkanethiol onto gold from dilute ethanolic solutions. The four possible combinations of the tail groups CH₃ and CH₂OH were investigated: Sh = CH₃/Lg = CH₂OH, Sh = CH₂OH/Lg = CH₃, Sh = CH₂OH/Lg = CH₂OH, and Sh = CH₃/Lg = CH,. The compositions of these SAMs are not the same as the compositions of the solutions from which they were formed. Although the relationship between the composition of the SAM and the composition of the solution suggests that some phase separation may be occurring within the SAM, contact angles with water and hexadecane show that significant disorder still remains in the interfacial region.     

Review: Polymers,Surface-Modified Polymers,and Self Assembled Monolayers as Surface-Modifying Agents for Biomaterials

Biocompatibility and nontoxicity of biomaterials are of utmost importance when foreign bodies come in contact with a biological system. Irrespective of the nature of material, nonspecific protein adsorption is the first process observed at surface–biological system interfaces followed by cellular processes. Nonspecific protein adsorption leads to deleterious cellular processes such as biofouling and finally immunological host response. Hence, surface modification becomes mandatory for preventing undesirable implant failure and inflammatory responses. Various polymers, surface-modified polymers and surfaces withself assembled monolayers, have been tested to tune surface properties for a given application. Surface functional groups and surface structures of polymers and copolymers regulate surface hydrophobicity, nonspecific protein adsorption, biomaterial stability, and antifouling property, etc. Self assembled monolayers are formed by covalent linkage with more controlled surface structure and smoothness. Mixed and hybrid self assembled monolayers containing both hydrophilic and hydrophobic groups result in moderate wettability. Further, we have discussed different methods of surface modification using polymers, modified polymers, and self assembled monolayers for improved surface biocompatibility and nonfouling properties.     

Determination of heavy metal ions in mixed solution by imprinted SAMs

Specific selectivity toward different heavy metal ions could be introduced into self-assembled monolayers (SAMs) by ion imprinting. In the mixed solution, good response toward mercury ions could be obtained on mercury ions imprinted SAMs, the copper ions imprinted SAMs presented good selectivity toward copper ions, while on lead ions imprinted SAMs, significantly higher insertion of lead ions than mercury and copper ions were observed. Linear calibration plots were obtained for each heavy metal ion and the regression equations were: [Hg(II)]/(10⁻⁶ M), [Cu(II)]/(10⁻⁶ M) and [Pb(II)]/(10⁻⁶ M) for mercury, copper and lead ions, respectively. The detection limits were determined to be: 1.46×10⁻⁸ M for Hg(II), 3.73×10⁻⁸ M for Cu(II) and 4.34×10⁻⁸ M Pb(II). The decreases in current response for mercury, copper and lead ions in the presence of 100-fold interferential ions were: 3.37%, 9.16% and 7.60%, respectively. Acceptable recoveries were obtained in mixed solutions at both high and low concentrations.     

Molecular-level design of binary self-assembled monolayers on polycrystalline gold electrodes

In this study, we followed up, by measuring the reductive desorption patterns, the time-dependent growth of the self-assembled monolayer (SAM) of a thiol compound (typically cysteine) formed on polycrystalline Au (poly-Au) electrode. Cysteine molecules appeared to adsorb preferentially and consecutively at the Au(1 1 0), Au(1 0 0) and then at the Au(1 1 1) surface domains of the poly-Au. A 95% surface coverage of cysteine (Γ_cysteine) was attained after 5 s, 120 s and more than 300 s for the Au(1 1 0), Au(1 0 0) and Au(1 1 1) domains, respectively, of the poly-Au electrode. The electrochemical reduction of molecular oxygen (O₂) in O₂-saturated 0.5 M KOH was utilized as a probing reaction for the extent of the compactness of the SAM. A binary SAM of two thiols (cysteine and cystamine) has been successfully designed over the poly-Au electrode at which a precise positioning of cysteine was achieved, i.e., cysteine was attached to the Au(1 1 1) domains, while cystamine to the Au(1 0 0) and Au(1 1 0) domains. SEM images for the electrodeposited Ag over the cysteine sub-SAM/Au electrode gave a possible mapping of the Au(1 1 1) domains of the poly-Au electrode.     

Electrochemical and optical microscopy study of red pepper seed oil corrosion inhibition by self-assembled monolayers (SAM) on 304 SS

Corrosion inhibition by red pepper seed oil (capsicol) on 304 stainless steel (SS) was studied in 1 M HCl solutions. The oil was extracted from the seed of the red pepper (Capsicum annuum L.), which was cultivated in East Java, Indonesia. Electrochemical and optical microscopy techniques were used to observe the performance of the corrosion-inhibition process. The inhibition efficiency reached 92.32% for an immersion time in capsicol of 30 min at room temperature and decreased with temperature. This inhibition behavior by capsicol was also justified by comparing the pictures of the samples with and without the inhibitor after corroding for one week.     

仿生法制备功能陶瓷薄膜材料

介绍了一种新的功能陶瓷薄膜制备方法——仿生法。该方法不同于传统的湿化学方法，如水热合成法、熔胶凝胶法、电化学法等，其突出特点是无外加电场，不需要调制熔胶或者凝胶，可以在常温常压下合成。该方法涉及两个关键点：基板表面的修饰和溶液条件的控制。我们在基板(单晶硅，玻璃等)的表面通过化学吸附的方式生长了一层自组织单分子层，然后将这层单分子层部分暴露在紫外光下，使暴露部分发生光化学反应，从而生成与未暴露部分不同的新的官能团。以此为模板，在适合的溶液条件下(溶液的过饱和度等)，通过溶液与模板表面官能团之间的选择性的物理化学作用，实现了从溶液中直接制备位置、形貌、结晶形态等可控的功能陶瓷薄膜。作者以SrTiO3为例简单介绍了这种新的合成方法。     

自组装单分子膜在生物传感器中的应用

论述了单分子膜及其在生物传感器中的应用。构成单分子膜组分化学参数的简单、连续可调决定了生物传感器的性质完全可控,取向有序、稳定可靠的单分子膜是生物传感器理想的基底材料。     

地空导弹武器系统可靠性分析及指标论证研究

可靠性是武器系统战技指标的重要内容,如何将比较成熟的可靠性理论应用到具体的装备可靠性论证工作当中,是一个值得研究的课题。针对地空导弹武器(surface-to-air missile,SAMs)系统这种具体类别的武器装备,在分析武器系统组成和战斗工作时序的基础上,对其工作可靠性逻辑和可靠性指标选取论证进行了研究,并给出了2个指标的计算思路,最后,讨论了地空导弹武器可靠性增长试验中的问题。     

Highly oriented ZnO rod arrays on Si substrates from aqueous solution

Ordered zinc oxide （ZnO） rod arrays with very high orientation were fabricated on Si substrates by using a solution method. The substrate surfaces were functionalized by Self-Assembly Monolayers （SAMs）. In the very early growth stage, the oriented ZnO crystals had already grown, which appeared to be the main reason why ZnO nanorods showed very high orientation. The un-dense and un-uniform SAMs provided a surface that was heterogeneous to ZnO nucleation. Consequently, highly oriented ZnO rods were selectively grown on the ＂coin-like＂ SAM-uncovered regions. The route developed here can provide some helpful information to control the nucleation and orientation of ZnO in aqueous solution. Also, the site-selective growth mechanisms can indicate a clue to grow patterned highly oriented ZnO nanorod arrays by the organic template.