Au纳米颗粒的形状和尺寸对表面等离子体的影响

通过调控Au纳米颗粒的形状和尺寸,研究了Au纳米颗粒的形状和尺寸与表面等离子体之间的关系。通过直流磁控溅射的方法在外延片上溅射Au薄膜,并采用快速热退火和常规热退火两种方式对其进行热退火,制备出Au纳米颗粒。使用不同热退火方式、不同热退火温度及不同Au薄膜厚度来改变Au纳米颗粒的形状和尺寸,并对Au纳米颗粒的表面形貌及它的消光谱进行了分析,对比了不同形貌的Au纳米颗粒对表面等离子体共振特性的影响。实验结果表明,使用普通热退火制备的Au纳米颗粒形状接近球体,而使用快速热退火得到的Au纳米颗粒的形状更接近棒体;随着热退火温度的升高,表面等离子体的共振波长发生红移;随着Au薄膜厚度的增加,表面等离子体的共振波长也发生红移。     

Highly Stable Au Nanoparticles with Tunable Spacing and Their Potential Application in Surface Plasmon Resonance Biosensors

Colloidal Au‐amplified surface plasmon resonance (SPR), like traditional SPR, is typically used to detect binding events on a thin noble metal film. The two major concerns in developing colloidal Au‐amplified SPR lie in 1) the instability, manifested as a change in morphology following immersion in organic solvents and aqueous solutions, and 2) the uncontrollable interparticle distance, determining probe spacing and inducing steric hindrance between neighboring probe molecules. This may introduce uncertainties into such detecting techniques, degrade the sensitivity, and become the barricade hampering colloidal Au‐based transducers from applications in sensing. In this paper, colloidal Au‐amplified SPR transducers are produced by using ultrathin Au/Al₂O₃ nanocomposite films via a radio frequency magnetron co‐sputtering method. Deposited Au/Al₂O₃ nanocomposite films exhibit superior stability, and average interparticle distances between Au nanoparticles with similar average sizes can be tuned by changing surface coverage. These characteristics are ascribed to the spacer function and rim confinement of dielectric Al₂O₃ and highlight their advantages for application in optimal nanoparticle‐amplified SPR, especially when the probe size is smaller than the target molecule size. This importance is demonstrated here for the binding of protein (streptavidin) targets to the probe (biotin) surface. In this case, the dielectric matrix Al₂O₃ is a main contributor, behaving as a spacer, tuning the concentration of Au nanoparticles, and manipulating the average interparticle distance, and thus guaranteeing an appropriate number of biotin molecules and expected near‐field coupling to obtain optimal sensing performance.     

Tuning Dichroic Plasmon Resonance Modes of Gold Nanoparticles in Optical Thin Films

A simple method is presented to tune the gold surface plasmon resonance (SPR) modes by growing anisotropic nanoparticles into transparent SiO₂ thin films prepared by glancing angle deposition. In this type of composite film, the anisotropy of the gold nanoparticles, proved by gracing incidence small angle X‐ray scattering, is determined by the tilted nanocolumnar structure of the SiO₂ host and yields a strong film dichroism evidenced by a change from an intense colored to a nearly transparent aspect depending on light polarization and/or sample orientation. The formation in these films of lithographic non‐dichroic SPR patterns by nanosecond laser writing demonstrates the potentialities of this procedure to develop novel optical encryption or anti‐counterfeiting structures either at micrometer‐ or macroscales.     

Surface Plasmon Resonance Sensors Based on Polymer Optical Fiber

Surface Plasmon Resonance （SPR） is a powerful technique for directly sensing in biological studies, chemical detection and environmental pollution monitoring. In this paper, we present polymer optical fiber application in SPR sensors, including wavelength interrogation surface enhanced Raman scattering SPR sensor and surface enhanced Raman scattering （SERS） probe.
Long-period fiber gratings are fabricated on single mode polymer optical fiber （POF） with 120 μm period and 50% duty cycle. The polarization characteristic of this kind of birefringent grating is studied. Theoretical analysis shows it will be advantageous in SPR sensing applications.     

Supported Faceted Gold Nanoparticles with Tunable Surface Plasmon Resonance for NIR‐SERS

A novel dry plasma methodology for fabricating directly stabilized substrate‐supported gold nanoparticle (NP) ensembles for near infrared surface enhanced Raman scattering (NIR SERS) is presented. This maskless stepwise growth exploits Au‐sulfide seeds by plasma sulfidization of gold nuclei to produce highly faceted Au NPs with a multiple plasmon resonance that can be tuned from the visible to the near infrared, down to 1400 nm. The role of Au sulfidization in modifying the dynamics of Au NPs and of the corresponding plasmon resonance is discussed. The tunability of the plasmon resonance in a broad range is shown and the effectiveness as substrates for NIR SERS is demonstrated. The SERS response is investigated by using different laser sources operating both in the visible and in the NIR. SERS mapping of the SERS enhancement factor is carried out in order to evaluate their effectiveness, stability, and reproducibility as NIR SERS substrates, also in comparison with gold NPs fabricated by conventional sputtering and with the state‐of‐the‐art in the current literature.     

表面等离子体共振传感器自适应测量光路

提出了一种用于表面等离子体共振（SPR）传感器的双棱镜自适应光路设计。采用2个完全相同的等腰直角三棱镜,1个作为Kretschmann棱镜结构传感器的元件,另1个作为光路的调整元件。当入射光固定,对双棱镜结构进行角度扫描时,出射光与入射光始终平行,只随着出射点的改变发生小的平移,利用凸透镜进行会聚,可以实现扫描过程中光探测器的固定不动。它避免了传统角扫描SPR传感器需要θ／2θ转角仪来对棱镜和光探测器分别进行θ和2θ角旋转的复杂结构,减少了运动部件,使仪器装置结构简单、紧凑、操作简便。     

Use of Reversal Nanoimprinting of Nanoparticles to Prepare Flexible Waveguide Sensors Exhibiting Enhanced Scattering of the Surface Plasmon Resonance

A flexible surface plasmon resonance (SPR)‐based scattering waveguide sensor is prepared by directly imprinting hollow gold nanoparticles (NPs) and solid gold NPs onto flexible polycarbonate (PC) plates—without any surface modification—using a modified reversal nanoimprint lithography technology. Controlling the imprinting conditions, including temperature and pressure, allows for the fine adjustment of the depths of the embedded metal NPs and their SPR properties. This patterning approach exhibits a resolution down to the submicrometer level. A 3D finite‐difference time domain simulation is used to examine the optical behavior of light propagating parallel to the air/substrate interface within the near‐field regime. Consistent with the simulations, almost an order of magnitude enhancement in the scattering signal after transferring the metal NPs from the glass mold to the PC substrate is obtained experimentally. The enhanced signal is attributed to the particles' strong scattering of the guiding‐mode waves (within the waveguide) and the evanescent wave (above the waveguide) simultaneously. Finally, the imprinting conditions are optimized to obtain a strongly scattering bio/chemical waveguide sensor.     

准分布式光纤表面等离子体波传感器

研究了一种基于波分复用原理的准分布式光纤表面等离子体波传感器。应用光波导理论和多层膜反射理论分析了表面等离子体波效应在同一光纤探头中连续被激励的原理及其传感模型。通过数值模拟和相应实验分别考察了蒸镀调制层对表面等离子体波共振(SPR)效果的影响,并在此基础上给出了设计的一般步骤和原则。实验结果表明,蒸镀不同厚度的Ta2O5薄膜将导致表面等离子体波共振光谱发生偏移,且随着膜厚增加而逐渐发生红移;当液体折射率n0处于1.333~1.388之间时,蒸镀有Ta2O5薄膜的光纤表面等离子体波传感器波长灵敏度达到2235 nm/RIU(Refractive Index Unit);通过在一支光纤探头上依次加工两个表面等离子体波传感区域,实现了对光波信号的连续调制。     

Designing Multicolor Micropatterns of Inverse Opals with Photonic Bandgap and Surface Plasmon Resonance

Structural coloration provides unique features over chemical coloration, such as nonfading, color tunability, and high color brightness, rendering it useful in various optical applications. To develop the structural colors, two different mechanisms of coloration–photonic bandgap (PBG) and surface plasmon resonance (SPR)–have been separately utilized. In this work, a new method is suggested to create structurally colored micropatterns by regioselectively employing SPR in a single film of inverse opal with PBG. The inverse opals are prepared by thermal embedding of opal into a negative photoresist and its subsequent removal. The inverse opals have a hexagonal array of open pores on the surface which serves as a template to make SPR‐active nanostructures through a directional deposition of gold, a perforated gold film and an array of curved gold disks are formed. With a shadow mask lithographically prepared, the gold is regioselectively deposited on the surface of the inverse opal, which results in two distinct regions of gold‐free inverse opal with PBG and gold nanostructure with SPR. As PBG and SPR develop their own structural colors respectively, the resultant micropatterns exhibit pronounced dual colors. More importantly, the micropatterns show the distinguished optical response for evaporation of volatile liquids that occupy the pores.     

Mixed Aerogels from Au and CdTe Nanoparticles

Mixed metal–semiconductor nanocrystal aerogels are fabricated, which are light‐emitting and highly porous macroscopic monoliths. Thiol‐stabilized CdTe and Au nanoparticles from aqueous synthesis act as building blocks for the hybrid material. The Au colloids undergo a surface‐modification to enhance the particle stability and achieve thiol functionalities. A photochemical treatment is applied for the gelation process which is found to be reversible by subsequent addition of thiol molecules. Via supercritical drying aerogels are formed. The variation of the initial CdTe to Au nanoparticle ratio permits a facile tuning of the content and the properties of the resulting aerogels. The obtained structures were characterized by means of optical spectroscopy, electron microscopy, elemental analysis, and nitrogen physisorption.     

The Interplay between Surface Plasmon Resonance and Switching Properties in Gold@Spin Crossover Nanocomposites

Rod‐like gold nanoparticles are directly embedded in a 1D‐polymeric spin crossover (SCO) material leading to singular Au@SCO nanohybrid architectures. The resulting architectures are designed to promote a synergetic effect between ultrafast spin‐state photoswitching and photothermal properties of plasmonic nanoparticles. This synergy is evidenced by the strong modulation of the surface plasmon resonance of the gold nanorods through the spin‐state switching of the SCO component and also the strong enhancement of the photoswitching efficiency compared to pure SCO particles. This remarkable synergy results from the large modulation of the dielectric properties of the SCO polymer upon its thermal switching and the enhancement of the heating of these hybrid nanostructures upon excitation of the surface plasmon resonance of the gold nanorods.     

Ag、Au纳米颗粒的激光表面修饰

通过用Nd：YAG激光（λ=1064nm）对氧化还原法制备的Ag、Au纳米颗粒的修饰,使Ag、Au纳米颗粒的尺寸均匀性得到更好的改善。用透射电子显微镜（TEM）和紫外-可见表面等离于体吸收（SPA）光谱对激光修饰后的Ag、Au纳米颗粒进行了测量和表征,结果表明,这些被修饰过的Ag、Au纳米颗粒由于自身体系发生了改变,可以作为更高效表面增强拉曼光谱（SERS）的增强基底。     

光纤表面等离子体波共振温度传感器的研究

根据液体折射率随温度变化而改变的特性，提出了一种基于表面等离子体波共振(SPR)效应的新型光纤温度传感器，分析了表面等离子体波共振光纤探头感应环境温度变化的原理。对表面等离子体波共振探头结构进行了优化设计，并进行了相关实验，为实现高折射率液体介质的感温测试和扩大测温范围提供依据。通过自行设计的一套光纤温度传感测试系统，得到系统输出的表面等离子体波共振光谱信号随温度变化的特性曲线，并提出对共振波长和最小光强反射率进行实时双参数测量的方法。实验结果表明，该测试系统具有结构简单、全光纤化、易远程测量等优点。     

用表面等离子体谐振（SPR）测量物质的折射率

本文介绍一种用表面等离子体谐振间接测量物质折射率的新方法。从理论上对这种方法作了论证,运用这种方法对ＬＢ膜做了测试实验,推算出其折射率,并且分析了这种方法适用特点。     

表面化学修饰对CdS纳米粒子三阶光学非线性的影响

用反胶束法制备了表面修饰 AOT-SO- 3(磺基琥珀酸双 -2 -乙基己酯钠盐的阴离子 )的 Cd S纳米粒子与表面修饰 Py(吡啶 )的 Cd S纳米粒子。采用背相简并四波混频 (DFWM)的方法研究了它们的三阶光学非线性。结果表明当 Cd S纳米粒子表面上的 AOT-SO- 3被 Py取代后 ,其三阶非线性极化率增加 ,这归于表面修饰 Py的Cd S纳米粒子具有长寿命的表面受陷电子 -空穴分离态 ,从而提高了对激子吸收的漂白效率 ,增加了三阶光学非线性。     

Enhancement of Phosphorescence by Surface‐Plasmon Resonances in Colloidal Metal Nanoparticles: The Role of Aggregates

The spectroscopic and near‐field scanning optical microscopy (NSOM) studies of phosphorescent films doped with colloidal gold nanoparticles (NPs) are presented. Films with a high concentration of 2,3,7,8,12,13,17,18‐octaethyl‐21H,23H‐porphine platinum(II ) dispersed in a neutral polymer poly[(methyl methacrylate)‐co‐(ethyl acrylate)] demonstrate a twofold increase of the phosphorescence quantum yield after the addition of aggregated NPs. In materials doped with unaggregated particles, a decrease of the emission yield is observed. Theoretical modeling of the phosphorescence transients suggests a minimization of the triplet–triplet quenching owing to the presence of fast processes that decrease the concentration of chromophores in the excited state and may be both of radiative and non‐radiative origin. NSOM examination of the films reveals increased light emission around large NP clusters. This observation demonstrates significant enhancement of the spontaneous emission rates by the large aggregates, although unaggregated NPs introduce mostly phosphorescence quenching sites.     

Realizing both improved luminance and stability in organic light-emitting devices based on a solution-processed inter-layer composed of MoOX and Au nanoparticles mixture

We report on the solution-processed mixture of Au nanoparticles (NPs) and MoO_X as an inter-layer in organic light-emitting devices (OLEDs), leading to the enhanced light emission and good stability. An impressive enhancement in current efficiency and power efficiency is achieved up to 70% and 100%, respectively. A systematic study to the effect of the Au NPs:MoO_X inter-layer on OLEDs demonstrates that the improved electrical properties is mainly ascribed to the enhanced hole injection due to the high work function of MoO_X and the good conductivity of Au NPs, and the enhanced optical properties is mainly attributed to the localized surface plasmon induced by Au NPs, which makes a great contribution to the improved efficiency. Besides, Au NPs:MoO_X inter-layer also behaves superior to the frequently-used polyethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS) in device stability. The decay ratio for Au NPs:MoO_X based device is 60% after 80 h, while it is nearly dying out for the device with PEDOT:PSS inter-layer.     

Colloidal Stability and Surface Chemistry Are Key Factors for the Composition of the Protein Corona of Inorganic Gold Nanoparticles

To study the influence of colloidal stability on protein corona formation, gold nanoparticles are synthesized with five distinct surface modifications: coating with citric acid, bis(p‐sulfonatophenyl)phenylphosphine dihydrate dipotassium salt, thiol‐terminated methoxy‐polyethylene glycol, dodecylamine‐grafted poly(isobutylene‐alt‐maleic anhydride), and dodecylamine‐grafted poly(isobutylene‐alt‐maleic anhydride) conjugated with polyethylene glycol. The nanoparticles are incubated with serum or bronchoalveolar lavage fluid from C57BL/6 mice (15 min or 24 h) to assess the effect of differential nanoparticle surface presentation on protein corona formation in the air–blood barrier exposure pathway. Proteomic quantification and nanoparticle size measurements are used to assess protein corona formation. We show that surface modification has a clear effect on the size and the composition of the protein corona that is related to the colloidal stability of the studied nanoparticles. Additionally, differences in the composition and size of the protein corona are shown between biological media and duration of exposure, indicating evolution of the corona through this exposure pathway. Consequently, a major determinant of protein corona formation is the colloidal stability of nanoparticles in biological media and chemical or environmental modification of the nanoparticles alters the surface presentation of the functional epitope in vivo. Therefore, the colloidal stability of nanoparticles has a decisive influence on nano–bio interactions.