二氧化硅包覆对纳米多孔金增强荧光特性的调制

为了减弱金属基底对表面增强荧光的淬灭效应,设计了增强效果更好的荧光增强基底。采用化学生长二氧化硅的方法对纳米多孔金(NPG)表面进行修饰,避免荧光分子和NPG表面直接接触引起的淬灭效应,在SiO_2@NPG表面分别组装上罗丹明6G(R6G)和辐射中心波长为700 nm的量子点(QD 700)。通过探测分析荧光光谱,可以得出:二氧化硅包覆的基底可以使表面增强荧光得到显著的增强,并且二氧化硅厚度对荧光强度有调节作用;在基底增强量子点荧光信号的同时,量子点和NPG之间还出现非辐射的能量转移现象,二氧化硅的厚度对能量转移同样有调节作用,厚度约为5 nm时能量转移现象最显著。本实验为基于荧光能量转移的检测以及设计更好的荧光增强基底提供了参考。     

SPR生物传感技术的研究进展与应用

由于具有实时、免标记、高灵敏度等优点,表面等离体子共振(surface plasmon resonance,SPR)技术被广泛应用于生物分子相互作用的研究分析。在SPR能够检测的分子量范围内,基本所有的具有特异性反应的生物分子都可以被SPR生物传感器检测。因此,SPR技术越来越展示出其重要的应用价值,成为近几年来研究的热点。本文重点从原理、技术改进以及应用等三个角度对SPR技术进行阐述,并从技术改进方面重点介绍了SPR技术的两个发展:表面等离子体子共振成像(SPRi)技术与局域表面等离子体子技术(LSPR)。     

激光扫描共聚焦表面等离子体共振系统实时监测单链DNA构象变化

脱氧核糖核酸(DNA)是染色体的重要组成部分,是一种主要的遗传物质,很多实验方法与理论模型被用来研究DNA与一些重要生物物种相互作用引起的构象变化。采用激光扫描共聚焦表面等离子体共振(LSCI-SPR)系统研究了一种特定单链DNA(ssDNA)分别与其互补DNA(cDNA)和汞离子(Hg~(2+))作用后的构象变化。将一端有荧光分子的ssDNA修饰在表面等离子体共振系统传感芯片上,通过观察荧光图像的变化来确定ssDNA与cDNA及Hg~(2+)之间相互作用而导致的构象变化,并通过动力学曲线计算出二者的结合速率分别为3.33×10~(-5) s~(-1)和1.42×10~(-4) s~(-1)。对于ssDNA-cDNA的相互作用,荧光图像没有变化。对于ssDNA-Hg~(2+)的相互作用,在通入Hg~(2+)后荧光发生猝灭。这些结果表明,激光扫描共聚焦表面等离子体共振系统在高灵敏实时监测ssDNA与其他特殊生物分子作用产生的构象变化和计算动力学参数方面有着广阔的应用前景。     

激光辐照制备银纳米基底及其用于葡萄糖检测

通过激光辐照的方法制备银纳米条纹表面增强拉曼散射基底,该基底具有制备方法简单、均匀性好、重复性强的优点。用巯基吡啶(4-MPY)作为探针分子,葡萄糖和葡萄糖氧化酶产生的过氧化氢会改变银纳米条纹的形貌,进而影响探针分子的表面增强拉曼光谱强度,从而实现葡萄糖的间接检测。得到的探针分子的表面增强拉曼光谱的强度与葡萄糖溶液的浓度具有较好的线性关系。实验结果表明,该基底在葡萄糖的检测及定量分析方面具有良好的应用前景。     

人工局域表面等离子体中环偶极子耦合效应研究

为了研究微波频率下人工局域表面等离子体中环偶极子的激励和耦合效应,设计了双层紧凑型金属圆盘结构。该金属圆盘结构由双层单裂谐振环阵列及介质板组成。采用微波激发该结构上层环偶极子模式,再利用介质板耦合到下层环偶极子,实现环偶极子级联耦合。通过调整上下谐振环的阵列数量,谐振口的大小以及中间介质板的介电系数的变化,获得双层阵列的上下环偶极子模式的耦合结果。研究结果表明,该模式可以产生多峰环偶极子效应,丰富了对人工局域表面等离子体中环偶极子模式间耦合效应的认识,可为新型传感器的设计和应用提供参考。     

表面等离子共振生物传感器技术及在生命研究中的应用

表面等离子体共振（Surface Plasmon Resonance,SPR）是一种入射光照射引起金属表面产生等离子体共振而导致反射光衰减的现象,反射光衰减程度与入射角和金属表面物质质量相关。根据这一原理研制的表面等离子体传感器,在检测、分析生物分子问的相互作用等方面有广泛的应用前景。本文对表面等离子共振生物传感器的工作原理、技术参数、检测方法进行了详细介绍,同时介绍了表面等离子共振技术在免疫检测、药物代谢及其蛋白质动力学等生命研究中的应用。     

纳米多孔银的制备及其表面增强拉曼散射特性研究

表面增强拉曼散射(SERS)因其具有高达单分子检测量级的灵敏度，在医学诊断、食品安全、环境监测等领域有着较大的应用前景。制备具有高密度“热点”的SERS基底是这项技术走向实际应用的关键。双连续结构的纳米多孔金属由于近邻纳米结构之间的耦合效应，所以具有很好的SERS增强特性。采用溅射方法制备了银锌合金前驱体，采用自由脱合金工艺和电化学脱合金工艺制备了具有纳米多孔结构的银基底，通过调制脱合金参数，获得了具有高增强因子的SERS基底。所制备的纳米多孔银基底对结晶紫的检测极限达到了10^-12 mol/L，可应用于超灵敏检测。     

荧光共振能量转移显微术及其新进展

本文叙述荧光共振能量转移显微术及荧光寿命成像显微术的原理、方法及特点。同时介绍利用荧光共振能量转移显微术研究信号分子Rac蛋白在3T3成纤维细胞内的定位及活化过程,以及利用荧光共振能量转移—荧光寿命成像显微术研究转录因子CAATT/增强子结合蛋白α在小鼠垂体细胞内的二聚化现象。     

热处理对金纳米颗粒活性衬底的影响

利用退火工艺对拉曼增强衬底进行热处理,得到粒径和密度不同的金纳米颗粒拉曼增强衬底,并且此工艺不引入杂质离子。通过用生物大分子龙胆紫作为探针分子,对金纳米颗粒表面的表面增强拉曼散射(SERS)和表面增强荧光(SEF)进行研究发现,拉曼和荧光强度存在相同的变化趋势。研究结果表明:热处理可以优化SERS和SEF增强效果,为高效率、低成本的基于SERS和SEF效应生物化学传感器件的研究提供参考。     

超表面透镜的像差和成像技术探讨

本文讨论了超表面透镜像差与成像技术,介绍了超表面透镜应用原理,总结局域表面等离激元共振、惠更斯原理、截断波导原理、贝里相位原理四种单元结构,了解到每种单元结构超表面透镜应用要点,最后总结等离子体超表面透镜成像、全介质超表面透镜成像、金属/介质混合的超表面透镜成像的应用,明确不同形式超表面透镜应用侧重点,为超表面透镜像差与成像技术研发与创新积累经验。     

Surface Damage Characteristics of Self-Assembled Monolayers of Alkanethiols on Metal Surfaces

The effect of metal oxide layer on the nano-tribological characteristics of single chain alkanethiol (CH₃(CH₂) _n SH) self-assembled monolayers (SAMs) on various metal surfaces (gold, silver, copper) was investigated. In order to correlate the surface structures with the tribological characteristics, various surface analysis techniques such as Scanning Probe Microscopy, X-ray Photoelectron Spectroscopy, Secondary Ion Mass Spectrometry and Spectroscopic Ellipsometry were used. Results of surface analyses showed that thiols on a metal surface were susceptible to forming multilayers if the metal surface was oxidized before the thiol assembly process. From the friction and wear tests conducted using an Atomic Force Microscope and a Lateral Force Microscope, it was found that thiols on copper oxide surface could be easily removed even under a few nano-Newton normal load. On the other hand, thiols on gold and copper fresh surfaces (the surface which was made by minimizing oxide formation) could endure up to micro-Newton level loads. Based on these findings, it could be concluded that the nano-tribological characteristics of alkanethiol SAMs on various metal surfaces were largely dependent on the oxide layer that already formed on the metal surface before the thiol adsorption process.     

Controlled Synthesis and Optical Properties of Pure Gold Nanoparticles

Abstract

Gold nanoparticles were synthesized by laser ablation of a gold metallic disc at wavelengths of 532 nm and 355 nm with 7 ns pulse duration in the pure water. The colloidal gold nanoparticles were characterized by ultraviolet-visible absorption spectroscopy, transmission electron microscopy, and fluorescence spectrometry. The presence of a surface plasmon resonance peak around ～ 524 nm indicates the formation of gold nanoparticles. The formation efficiencies of gold nanoparticles in colloids were found to increase when ablating the gold metallic disc with a laser having a longer wavelength. The size distributions of the gold nanoparticles thus produced were measured by transmission electron microscopy. A reduction in mean diameter of the particles was observed with a decrease in the laser wavelength under the irradiation at a high fluence of 25 mJ/pulse. The fluorescence spectroscopy demonstrated that these gold nanoparticles are fluorescent, showing a strong blue emission intensity at 458 nm.     

表面等离子体共振理论仿真研究

为了掌握影响激发表面等离子体共振(SPR)现象的因素,文中以薄膜光学理论为基础,利用Winspall软件模拟研究Kretschman结构下,金膜厚度、待测介质折射率以及三棱镜类型对表面等离子体共振吸收峰位变化的影响,得出了最佳膜厚以及影响激发SPR现象的棱镜折射率和待测物质折射率随共振角度变化的规律,为SPR传感器的设...     

TM导模激励的对称型表面等离子体共振结构的研究

提出并研究了一种新的、可用TM导模激励的对称型表面等离子体共振结构,共振条件通过调节两金属薄膜之间的间隙来满足,提高了应用范围和使用灵活性。实验采用0．004AgNO3--0．996NaNO3混合盐制备了离子交换波导,金属膜为70nmAg膜,测试表明在两金属膜十分靠近时可以发生表面等离子体波的激发。     

Plasmonic effect of silver nanoparticles on the upconversion emissions of Sm3+-doped sodium-borosilicate glass

The effect of the localized surface plasmon resonance (SPR) on optical absorption and photoluminescence of Sm³⁺-doped sodium borosilicate glass containing reduced silver nanoparticles (NPs) is reported (Ag⁺ → Ag⁰). The interaction of ultraviolet light by metallic NPs and its effect on the optical properties of samarium in proposed glass were investigated by absorption and photoluminescence spectra analysis. The existence of the NPs was pursued by transmission electron microscopy technique, revealing the existence of Ag NPs with average size of ∼8–14 nm. The largest enhancement was achieved for emission at 561 nm. Such improvements were attributed and discussed by enhanced electric field around metallic NPs and energy transfer (ET) between Sm³⁺ ions and silver NPs.     

Environmental effects on the formation process of adhesive wear particles

Three kinds of experiments have been conducted to study the effect of environmental molecules on the formation process of adhesive wear particles. First, the growth process of transfer particles was continuously observed by scanning electron microscope. It was understood that the growth of the transfer particles was due to the continuous conversion of the disc surface material into transfer particles. Next, wear tests between a Sn pin and Sn disc were conducted in an oxygen environment from 7 × 10⁻³ Pa to 1.0 × 10⁵ Pa. The size and hardness of wear particles and the wear volume increased with increasing oxygen pressure. Wear tests between Sn and Sn were also conducted while Au metals were sputter-deposited onto the friction surface. The deposition of Au had the same effect on the size and hardness of the wear particles as the oxygen atmosphere. In general, the hardness of metals is increased by the small amount of impurity atoms in them. The inclusion of oxygen or gold atoms on the surface and in the transfer particle is supposed to have the same effect of enhancing the shear strength of the interface and the transfer particles. This is the possible mechanism of the continuous shear fracture within the bulk which results in the growth of transfer particles.     

Analysis of 2-Benzo[c]cinnoline Nanofilm at the Gold Surface

Abstract

A polycrystalline gold surface was modified with 2-benzo[c]cinnoline (BCC) in nonaqueous media using cyclic voltammetry. A multilayer BCC nanofilm at the gold surface was formed by the electrochemical reduction of 2-benzo[c]cinnoline diazonium salt (BCC-DAS). Grafting of BCC molecules onto the gold surface was verified by cyclic voltammetry using various redox probes, electrochemical impedance spectroscopy, and Raman spectroscopy. The BCC film thickness was measured by ellipsometry and calculated as 46 nm indicating a multilayer film formation. The stability and the potential range of the novel Au-BCC modified electrode were also studied in open atmosphere and pure water. The working potential range of Au-BCC electrode was found to be between ?1.8 and +1.6 V.     

Time-lapse FRET microscopy using fluorescence anisotropy

We present recent data on dynamic imaging of Rac1 activity in live T-cells. Förster resonance energy transfer between enhanced green and monomeric red fluorescent protein pairs which form part of a biosensor molecule provides a metric of this activity. Microscopy is performed using a multi-functional high-content screening instrument using fluorescence anisotropy to provide a means of monitoring protein–protein activity with high temporal resolution. Specifically, the response of T-cells upon interaction of a cell surface receptor with an antibody coated multi-well chamber was measured. We observed dynamic changes in the activity of the biosensor molecules with a time resolution that is difficult to achieve with traditional methodologies for observing Förster resonance energy transfer (fluorescence lifetime imaging using single photon counting or frequency domain techniques) and without spectral corrections that are normally required for intensity based methodologies.     

Nanoscopic observation of a gold nanoparticle-conjugated protein using near-field scanning optical microscopy

This study describes a single gold nanoparticle (AuNP)-based observation of biomolecular interaction using a near-field scanning microscope (NSOM) in transmission mode. To observe streptavidin molecules, a glass surface was first patterned with a micro-scale line of (3-aminopropyl)trimethoxysilane (APTMS) by micro-contact printing (μCP) with a subsequent reaction of N-hydroxysuccinimide (NHS)-biotin. The AuNP-conjugated streptavidin was then applied to the biotin-modified glass surface and NSOM was employed to detect the resulting specific interaction between streptavidin and biotin on the glass surface. Using the optical and topological images generated from the NSOM analysis, the interaction could be observed at the nanoscopic scale. This study demonstrates that the NSOM is a powerful tool for the detection of protein interactions at the nanoscopic level when the protein is conjugated with AuNPs.