表面等离子体共振光谱技术与电化学方法联用及其应用

表面等离子体共振（Surface Plasmon Resonance,SPR）技术是利用金属薄膜光学耦合产生的物理光学现象建立的一种非常灵敏的光学分析手段. 近年发展的电化学表面等离子体共振（Electrochemical Surface Plasmon Resonance,EC-SPR）是将时间分辨表面等离子体共振光谱技术与电化学方法联用的一种新技术. 本文介绍了SPR和EC-SPR的基本原理,并重点阐述了时间分辨SPR光谱技术与电化学方法联用及应用,该技术已广泛地应用于反应动态过程研究、生物化学传感器、电极/溶液界面的表征、动力学常数的测定以及生物分子相互作用等领域.     

鸟嘌呤、鸟苷及其甲基化衍生物的近红外傅里叶变换表面增强拉曼光谱

本文给出了采用表面增强傅里叶变换拉曼光谱法测定的鸟嘌呤、鸟苷及其甲基化衍生物的拉曼散射。实验结果表明，采用了近红外波长的拉曼散射及傅里叶变换技术成功地获得鸟嘌呤、鸟苷及其甲基化衍生物的水溶液在较低浓度下（0．1～0．01mg／L）不受荧光干扰的拉曼光谱图，其频率与相对强度分布表明，水溶液状态下吸附在Ag膜上的鸟嘌呤（苷）及其衍生物结构中的有关振动谱带r（C＝O）、NH2和杂环上的N获得显著增强。本文对水溶液鸟嘌呤（苷）及其衍生物的FT－Raman谱带的归宿进行了讨论。     

光波导耦合的表面等离子体共振光谱传感器实时监测表面生化反应

利用厚度为100 μm且局部表面覆盖有45 nm金膜的玻璃片作为消逝波表面敏感元件,自主设计并组装了光波导耦合的光谱表面等离子体共振(SPR)生化传感器.本仪器使用一对玻璃棱镜作为输入-输出耦合器,卤钨灯作为白光光源,利用时间分辨的CCD光谱分析仪对光波导输出光谱进行快速测定.这种光波导耦合的光谱SPR传感器灵敏度高,稳定性好,时间分辨率高,光谱窗口和动态探测范围宽,非常适合于表面生化反应的动力学测试.利用这种光波导耦合的光谱SPR传感器对金纳米粒子在半胱胺修饰的金膜表面的自组装过程进行了原位实时监测.     

血卟啉衍生物(HpD)的表面增强共振拉曼光谱

近年来,采用光敏剂(H_pD)与光的协同效应,诊治癌肿疾病有了较大的进展,所以,研究其光谱特性是有其现实意义的。 用共振拉曼光谱和表面增强拉曼光谱所获得的散射强度,都比通常的拉曼光谱有几个数量级的增强,并可得到稀溶液(10~(-6)～10~(-3)mol/L)的高质量光谱,本文报道了8×10~(-3)mol/L HpD水溶液的共振拉曼光谱和5×10~(-5)mol/L HpD水溶液的表面增强共振拉曼光谱,结果表明,表面增强共振拉曼光谱比共振拉曼光谱的散射强度滴出三个量级。     

帽状锌纳米结构的制备及其表面等离子体共振特性

利用真空热蒸发法在二氧化硅纳米粒子单层膜上沉积锌薄膜制备了帽状锌纳米结构. 采用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)和紫外-可见吸收光谱(UV-Vis)对样品的形貌、结构和光学特性进行了表征和研究. SEM照片表明所得到的复合纳米粒子为不完全包裹的帽状结构, 且其表面较粗糙. XRD分析结果显示在二氧化硅纳米粒子上沉积的锌膜呈多晶六角密堆结构. 吸收光谱研究表明, 帽状锌纳米结构在570～760 nm范围内具有明显的由纵向双极子表面等离子体共振引起的吸收峰, 且随着锌帽层厚度的增加或二氧化硅内核粒径的增大, 该吸收峰逐渐红移; 当内核粒径增大到500 nm时, 帽状锌纳米结构在412 nm附近还出现了一个四极子共振峰.     

纳米多孔金薄膜的表面等离子体共振传感特性

对淀积在玻璃衬底上厚度约60 nm的金银合金溅射薄膜进行硝酸腐蚀脱银处理, 得到纳米多孔金薄膜. 利用自建的波长检测型表面等离子体共振(SPR)传感装置研究了腐蚀时间对纳米多孔金薄膜SPR特性的影响, 结果发现纳米多孔金薄膜与水溶液接触后在400-900 nm光谱范围内不具有SPR效应, 而当薄膜置于空气中时会产生明显的传播等离子体共振吸收峰, 其共振波长随腐蚀时间增加逐渐红移. 纳米多孔金薄膜在空气气氛中的SPR效应使其能够用于原位监测气相分子在孔内的吸附, 还可对在液相中吸附的生化分子进行离位测试. 本文对L-谷胱甘肽、L-半胱氨酸、2-氨基乙硫醇三种含巯基的生化小分子在纳米多孔金薄膜内的吸附进行了离位分析, 结果表明与传统的致密金薄膜SPR芯片比较, 纳米多孔金薄膜对这些分子显示出更高的灵敏度和更低的检测下限, 这归功于多孔金的大比表面积使其能够吸附大量的生化小分子. 实验还对乙醇蒸气在纳米多孔金薄膜内的吸附进行了原位监测, 发现吸附平衡所用时间较长, 约为160 min.     

多孔硅上银纳米粒薄膜的制备及其表面增强红外光谱

通过简便的化学沉积法在多孔硅上制备银纳米粒薄膜用于表面增强红外光谱检测。通过Ag⁺与多孔硅表面的SiHx发生氧化还原反应将银纳米粒子沉积在多孔硅表面。红外探针分子溶解于无水乙醇中进而被均匀分散在多孔硅表面,实验结果显示：对氨基苯硫酚、对氨基苯甲酸和对氟苯硫酚3个探针分子的红外峰分别最大增强了10、85和21倍。银纳米粒的大小和形状等物理特性、探针分子是否有与银表面进行强结合的基团和芳烃结构、以及表面选律等因素影响表面增强红外的吸收效应。     

Au-Ag合金纳米粒子制备及其表面增强拉曼光谱研究

首先采用柠檬酸钠法制得Au-Ag合金纳米种子, 然后采用盐酸羟胺生长法得到不同组成的Au-Ag合金纳米粒子. 在其UV-Vis光谱中只观察到一个位于单金属银和金之间的等离子体共振峰, 表明Au-Ag合金纳米粒子已经形成. TEM结果表明, 合金纳米粒子的粒径约为60 nm, 且颜色均一, 没有明显的核壳结构. 用苯硫酚(TP)作为探针分子研究了合金纳米粒子的表面增强拉曼光谱(SERS). 结果表明, SERS强度与合金纳米粒子的组成和尺寸有关. 当纳米粒子粒径一定时, 除Au25Ag75外, 随着金的增加SERS强度增强. Au25Ag75的粒径比Ag小, 导致SERS强度比Ag低. Au50Ag50和Au75Ag25加入TP分子后, 其聚集方式与Au相似, 等离子体共振峰逐渐靠近1064 nm, 金含量较高时, TP的SERS归于聚集体的等离子体共振增强的贡献.     

激光诱导的对-叔丁基苯甲硫醇分子表面增强拉曼光谱变化

报道了对-叔丁基苯甲硫醇分子的表面增强拉曼光谱随激光照射时间增加而发生渐变的现象. 某些特征散射峰的相对强度按照一定的趋势发生渐变. 通过比较不同条件下光谱变化的速率, 认为激光的热效应是导致光谱发生变化的主要原因. 在对-叔丁基苯甲硫醇分子自组装形成单分子膜的过程中, 由于末端基团的空间位阻效应, 分子的排列和取向不易达到最佳状态, 激光的热效应使其发生进一步重排而趋于稳定.     

Au/Ag复合纳米笼在表面增强拉曼光谱中的应用

表面增强拉曼光谱（SERS）技术是一种基于贵金属纳米结构基底对被检测物进行高灵敏度检测的一种方法.具有特殊纳米结构的贵金属表面受到激光的照射时，金属表面的自由电子会受到极大的振荡，当入射光频率与振荡频率相近时，则会发生表面等离子体共振现象（SPR），使金属表面的局域电场强度极大增强，入射光强度和散射光强度都得到成倍的放大，从而使吸附在贵金属纳米结构表面的分子的拉曼散射信号得到有效的增强.使用NaBH₄还原-酸刻蚀模板法，制备了八面体Au/Ag复合纳米笼，其形貌规整，尺寸均匀约为600 nm，无Cu₂O模板的残留，Au元素均匀负载在Ag纳米笼上，质量分数约为16.8%；Au/Ag复合纳米笼的紫外可见吸收峰相对于Ag纳米笼发生了红移，更重要的是，Au和Ag元素协同赋予了复合纳米笼超高的SERS灵敏度和重复性，Au/Ag复合纳米笼实现了对罗丹明6G的痕量检测（5×10^-14 mol/L），通过时域有限差分法（FDTD）模拟证实：这主要归因于等离子共振作用产生的高电磁场强度；此外，Au元素的加入使Au/Ag复合纳米笼具有优异的抗氧化性和化学稳定性，即使在1%的H₂O₂溶液中浸泡3 h，仍然能够保持优异的SERS性能.八面体Au/Ag复合纳米笼有望成为一种具有应用前景的高灵敏度、高稳定性的SERS基底.     

Fourier Transform Surface Plasmon Resonance (FTSPR) with Gyromagnetic Plasmonic Nanorods

An unprecedented active and dynamic sensing platform based on a LSPR configuration that is modulated by using an external magnetic field is reported. Electrochemically synthesized Au/Fe/Au nanorods exhibited plasmonically active behavior through plasmonic coupling, and the middle ferromagnetic Fe block responded to a magnetic impetus, allowing the nanorods to be modulated. The shear force variation induced by the specific binding events between antigens and antibodies on the nanorod surface is used to enhance the sensitivity of detection of antigens in the plasmonics‐based sensor application. As a proof‐of‐concept, influenza A virus (HA1) was used as a target protein. The limit of detection was enhanced by two orders of magnitude compared to that of traditional LSPR sensing.     

Plasmonic/Nonlinear Optical Material Core/Shell Nanorods as Nanoscale Plasmon Modulators and Optical Voltage Sensors

Herein, we report the design and synthesis of plasmonic/non‐linear optical (NLO) material core/shell nanostructures that can allow dynamic manipulation of light signals using an external electrical field and enable a new generation of nanoscale optical voltage sensors. We show that gold nanorods (Au NRs) can be synthesized with tunable plasmonic properties and function as the nucleation seeds for continued growth of a shell of NLO materials (such as polyaniline, PANI) with variable thickness. The formation of a PANI nanoshell allows dynamic modulation of the dielectric environment of the plasmonic Au NRs, and therefore the plasmonic resonance characteristics, by an external electrical field. The finite element simulation confirms that such modulation is originated from the field‐induced modulation of the dielectric constant of the NLO shell. This approach is general, and the coating of the Au NRs with other NLO materials (such as barium titanate, BTO) is found to produce a similar effect. These findings can not only open a new pathway to active modulation of plasmonic resonance at the sub‐wavelength scale but also enable the creation of a new generation of nanoscale optical voltage sensors (NOVS).     

Ag Nanowire‐Ag Nanoparticle Hybrids for the Highly Enhanced Fluorescene Detection of Protoporphyrin IX Based on Surface Plasmon‐Enhanced Fluorescence

In this study, we developed an approach to fabricate novel 1D Ag NWs‐Ag NPs hybrid substrate for enhanced fluorescene detection of protoporphyrin IX (PpIX) based on surface plasmon‐enhanced fluorescence. The Ag NWs‐Ag NPs hybrid was synthesized by combining the hydrothermal method and self‐assembly method with the asisstance of polyvinylpyrrolidone (PVP). When the Ag NWs‐Ag NPs hybrid was deposited on the glass substrate and employed as active substrate to detect PpIX, the fluorescence intensity of PpIX was enhanced greatly due to the coupling effect of localized surface plasmon‐localized surface plasmon (LSP‐LSP) and localized surface plasmon‐surface plasmon propagation (LSP‐SPP) which induced great enhancement of the electromagnetic field. Furthermore, the enhancement effect was approximately linear when the concentration of PpIX was ranged from 1×10^?7 mol/L to 2×10^?5 mol/L, and the photobleaching phenomenon of PpIX was reduced greatly, indicating that the fabricated Ag NWs‐Ag NPs hybrid substrate had well performance for PpIX imaging. This work provides an effective approach to prepare highly sensitive and stable fluorescence enhancement substrate, and has great potential application in fluorescence imaging.     

帽状铝纳米粒子的制备及表面等离子共振特性

金属纳米材料具有许多独特的物理和化学性质,其中一个重要的光学性质就是表面等离子共振,然而在大多数情况下,金属纳米粒子表面等离子共振所产生的吸收峰被限制在相对狭小的范围内,很难进行调谐。近年来,以电介质为核金属为壳的核壳结构复合纳米材料成功的解决了这一问题,通过设计和剪裁内核的直径与外壳层厚度的比值,可以实现光学性质可调的特性[1～5]。此类复合材料可被广泛应用于光催化、传感器、光信息存储、生物光子学、生物医学等领域[6～11]。美国莱斯大学及德州的研究人员利用这类核壳结构纳米材料成功地实现了对体外乳腺肿瘤的杀灭实验[12]。在这种类型的材料中,对称性降低的即不完全包裹的纳米粒子如杯状[13]、帽状[13,14]、半球壳状[15]、月牙状[16]等核壳结构复合粒子由     

DNA‐Encoded Tuning of Geometric and Plasmonic Properties of Nanoparticles Growing from Gold Nanorod Seeds

Systematically controlling the morphology of nanoparticles, especially those growing from gold nanorod (AuNR) seeds, are underexplored; however, the AuNR and its related morphologies have shown promises in many applications. Herein we report the use of programmable DNA sequences to control AuNR overgrowth, resulting in gold nanoparticles varying from nanodumbbell to nanooctahedron, as well as shapes in between, with high yield and reproducibility. Kinetic studies revealed two representative pathways for the shape control evolving into distinct nanostructures. Furthermore, the geometric and plasmonic properties of the gold nanoparticles could be precisely controlled by adjusting the base compositions of DNA sequences or by introducing phosphorothioate modifications in the DNA. As a result, the surface plasmon resonance (SPR) peaks of the nanoparticles can be fine‐tuned in a wide range, from visible to second near‐infrared (NIR‐II) region beyond 1000 nm.     

High-sensitivity Mercury Ion Detection System Using Unmodified Gold Nanorods

Hg²⁺ is one of the most universal and severe toxic metal pollutants. Here we reported a high-sensitivity and rapid method for detection of Hg²⁺. The technique was based on the localized surface plasmon resonance property of gold nanorods. Neither modification of gold nanorods nor separation of analyte was necessary. The longitudinal absorption peak of gold nanorods presented a linear blue shift as Hg²⁺ concentration increased. The blue shift of longitudinal absorption peak was due to the changes of both aspect ratio and medium dielectric constant. The sensor had a wide linear interval ranging from 285 nM to 8.00 μM, the detection limit was as low as 112 nM, and the sensitivity was 30.48 nm μM^μ1, which were comparable to the performance of the modified sensors.     

Plasmonic response of ordered arrays of gold nanorods immersed within a nematic liquid crystal

We study theoretically the optical properties of a two-dimensional lattice of metallic (gold) nanorods immersed within a nematic liquid crystal (NLC) strongly anchored to the surface of the nanorods. The distribution of the director field of the NLC is found by minimising the corresponding total free energy via simulated annealing. Optical properties such as transmittance, reflectance and absorbance of the structure are found by employing a hybrid discrete-dipole approximation/layer-multiple-scattering technique. We show, in particular, that when the NLC is strongly anchored to the nanorods, light absorbance is more efficient compared to the case where the liquid crystal (LC) is aligned by application of an external field. Also, the alignment of the LC molecules via an external field leads to a significant shift of the surface-plasmon resonance of the gold nanorods relative to the strong-anchoring case, an effect which can be exploited in switching applications. We also report that the rate of light absorption is a non-monotonic function of the height of nanorods due to the guiding of EM waves taking place for long enough nanorods.     

压电增强的等离激元光催化材料Ag/BaTiO3的制备及性能研究

针对光催化过程中的低光利用率和低催化效率，采用光化学还原法将Ag纳米颗粒均匀修饰在BaTiO₃纳米压电材料表面，制备了x mol/L-Ag/BaTiO₃（x=0.01、0.02、0.04，x为Ag的浓度）等离激元压电光催化剂.研究了压电光催化过程中的反应机理及等离激元颗粒负载的浓度对光催化剂性能的影响.研究结果显示，0.02 mol/L-Ag/BaTiO₃在全光谱光辐照和超声激发的压电场的辅助下，在75 min内可降解91%的罗丹明B，将降解效率提升了21%，证实了纳米复合结构中压电势对表面等离激元光催化活性的重要影响.催化性能的提升源于压电效应和表面等离子体共振效应的协同作用.Ag纳米颗粒的等离子体共振效应（LSPR），使光吸收范围从紫外光区扩大至可见光波段.超声驱动可使BaTiO₃纳米压电体发生形变而于表面产生压电电荷，压电势的存在进一步增强了LSPR诱导的光生载流子分离，促进羟基自由基的生成，加速有机染料的降解.本工作将BaTiO₃的压电效应引入等离子体光催化中，可推广到其他材料和催化系统中，为环境净化提供一种有效的技术.     

金纳米棒的生长及与FeCl_3的作用

采用三氯化铁选择性刻蚀法获得了预定长径比的金纳米棒.相比于晶种生长法,三氯化铁选择性刻蚀法可以更加简便快捷地调控金纳米棒形貌.以三氯化铁为刻蚀剂的刻蚀反应优先发生在金纳米棒尖端,这是因为金纳米棒尖端反应活性更高且表面活性剂钝化作用更弱.通过控制刻蚀反应时间及刻蚀剂浓度,可以精确调控金纳米棒的长径比.实验结果表明,增加刻蚀剂浓度、卤素离子浓度以及升高反应温度可以加快刻蚀反应速率.进一步讨论了金属离子的刻蚀作用机理.