R6G单分子表面增强共振拉曼散射光谱探测研究

以共焦显微系统为平台，研究了不同浓度的R6G银溶胶的表面增强共振拉曼散射（SERRS）光谱，结果表明不同浓度溶液中的R6G分子表现出了不同的光谱特性。在浓度为10^-13mol·L^-1的R6G银溶胶中得到了R6G单分子的表面增强共振拉曼散射光谱，观察到了一些光谱非均匀变化现象，如谱色散、谱线的强度起伏、拉曼谱的偏振化以及分子的闪烁等，并对这些现象进行了分析，证明得到的是R6G单分子的SERRS光谱。文章还对单分子检测中的一些关键问题进行了分析与讨论，确定了单分子SERRS光谱检测的适当条件。

Surface-enhanced resonance Raman scattering spectroscopy of single R6G molecules

Surface-enhanced resonance Raman scattering (SERRS) of Rhodamine 6G (R6G) adsorbed on colloidal silver clusters has been studied. Based on the great enhancement of the Raman signal and the quench of the fluorescence, the SERRS spectra of R6G were recorded for the samples of dye colloidal solution with different concentrations. Spectral inhomogeneity behaviours from single molecules in the dried sample films were observed with complementary evidences, such as spectral polarization, spectral diffusion, intensity fluctuation of vibrational lines and even "breathing" of the molecules. Sequential spectra observed from a liquid sample with an average of 0.3 dye molecules in the probed volume exhibited the expected Poisson distribution for actually measuring 0, 1 or 2 molecules. Difference between the SERRS spectra of R6G excited by linearly and circularly polarized light were experimentally measured.

R6G/RedB/Ox725三元混合染料体系的研究

通过测量谱荧光光及荧光寿命探讨了RedB/Ox725的能量转移过程,并观察了R6G/RedB/Qx725三种染料混合的荧光光谱和超辐射模式的激光性能。结果表明,混合后Ox725在氮分子激光泵浦下的激光输出得到改善,且可扩展波长调谐范围。

Role of the N-terminal region in G protein-coupled receptor functions : negative modulation revealed by 5-HT2B receptor polymorphisms

The putative role of the N-terminal region of rhodopsin-like 7 transmembrane biogenic amine receptors in agonist-induced signaling has not yet been clarified despite recent advances in 7 transmembrane receptor structural biology. Given the existence of N-terminal nonsynonymous polymorphisms (R6G;E42G) within the HTR2B gene in a drug-abusing population, we assessed whether these polymorphisms affect 5-hydroxytryptamine 2B (5-HT2B) receptor in vitro pharmacologic and coupling properties in transfected COS-7 cells. Modification of the 5-HT2B receptor N terminus by the R6G;E42G polymorphisms increases such agonist signaling pathways as inositol phosphate accumulation as assessed by either classic or operational models. The N-terminal R6G;E42G mutations of the 5-HT2B receptor also increase cell proliferation and slow its desensitization kinetics compared with the wild-type receptor, further supporting a role for the N terminus in transduction efficacy. Furthermore, by coexpressing a tethered wild-type 5-HT2B receptor N terminus with a 5-HT2B receptor bearing a N-terminal deletion, we were able to restore original coupling. This reversion to normal activity of a truncated 5-HT2B receptor by coexpression of the membrane-tethered wild-type 5-HT2B receptor N terminus was not observed using a membrane-tethered 5-HT2B receptor R6G;E42G N terminus. These data suggest that the N terminus exerts a negative control over basal as well as agonist-stimulated receptor activity that is lost in the R6G;E42G mutant. Our findings reveal a new and unanticipated role of the 5-HT2B receptor N terminus as a negative modulator, affecting both constitutive and agonist-stimulated activity. Moreover, our data caution against excluding the N terminus and extracellular loops in structural studies of this 7 transmembrane receptor family

Spontaneous formation of branched nanochains from room temperature molten amides: visible and near-IR active, SERS substrates for non-fluorescent and fluorescent analytes

Highly stable, branched gold nanoworms are formed spontaneously in an acetamide-based room temperature molten solvent without any additional external stabilizing or aggregating agent. The nanoworms can be anchored onto solid substrates such as indium tin oxide (ITO) without any change in morphology. The anchored nanoworms are explored as substrates for surface enhanced Raman scattering (SERS) studies using non-fluorescent 4-mercaptobenzoic acid (4-MBA) and fluorescent rhodamine 6G (R6G) as probe molecules. The anchored nanostructured particles respond to near IR (1064 nm) as well as visible (785, 632.8 and 514 nm) excitation lasers and yield good surface enhancement in Raman signals. Enhancement factors of the order 10(6)-10(7) are determined for the analytes using a 1064 nm excitation source. Minimum detection limits based on adsorption from ethanolic solutions of 1028 M 4-MBA and aqueous solutions of 1027 M R6G are achieved. Experimental Raman frequencies and frequencies estimated by DFT calculations are in fairly good agreement. SERS imaging of the nanostructures suggests that the substrates comprising of three dimensional, highly interlinked particles are more suited than particles fused in one dimension. The high SERS activity of the branched nanoworms may be attributed to both electromagnetic and charge transfer effects.

Is chemically synthesized Graphene `really' a unique substrate for SERS and fluorescence quenching?

We demonstrate observation of Raman signals of different analytes adsorbed on carbonaceous materials, such as, chemically reduced graphene, graphene oxide (GO), multi-walled carbon nanotube (MWCNT), graphite and activated carbon. The analytes selected for the study were Rhodamine 6G (R6G) (in resonant conditions), Rhodamine B (RB), Nile blue (NBA), Crystal Violet (CV) and acetaminophen (paracetamol). All the analytes except paracetamol absorb and fluoresce in the visible region. In this article we provide experimental evidence of the fact that observation of Raman signals of analytes on such carbonaceous materials are more due to resonance effect, suppression of fluorescence and efficient adsorption and that this property in not unique to graphene or nanotubes but prevalent for various type of carbon materials.

Enhanced photocatalytic efficiency of AuPd nanoalloy decorated ZnO-reduced graphene oxide nanocomposites

Inhibition of electron-hole pair recombination is the most desirable solution for stimulating photocatalytic activity in semiconductor nanostructures. To implement this, herein we study the photocatalytic efficiency of elemental Au, Pd and bimetallic AuPd nanoalloy decorated pristine and reduced graphene oxide (RGO) hybridized ZnO nanorods for degrading rhodamine 6G (R6G) dye. Fabrication of Au, Pd and AuPd nanoalloy on pristine and RGO modified ZnO nanorods is simple and more importantly surfactant or polymer free. AuPd nanoalloyed ZnO-RGO nanocomposites exhibit higher photocatalytic activity for degrading dye than both Au and Pd hybridized ones, indicating the promising potential of bimetallic nanoalloys over elemental components. A non-monotonic dependence on the composite composition was found by analyzing photodegradation efficiency of a series of ZnO-RGO-AuPd hybrid nanostructures with different weight percentages of RGO. The hybrid nanostructure ZnO-RGO (5 wt%)-AuPd (1 wt%) exhibits highest photodegradation efficiency (similar to 100% degradation in 20 min) with an improvement in rate constant (k) by a factor of 10 compared to that of the ZnO-RGO nanocomposite. The enhancement of the photocatalytic activity is attributed to the better separation of photogenerated charge carriers in photocatalysts thereby suggesting possible usefulness in a broad range of applications, such as sensing, photocatalysis and solar energy conversion.

Probing single-molecule by surface-enhanced resonance Raman scattering with linearly and circularly polarized laser

Rhodamine 6G (R6G) was incubated in silver sols with different low concentrations and its surface-enhanced resonance Raman scattering (SERRS) spectra, excited by linearly and circularly polarized light, respectively, were studied. At the single-molecule level the SERRS spectra were recorded in 10(-13) M dye colloidal solution. Spectral inhomogeneous behaviors from single-molecule were observed such as spectral polarization, spectral diffusion and intensity fluctuations of vibrational lines. Difference between SERRS spectra of R6G excited by linearly and circularly polarized light and the effect of the polarizing angle of Raman signal relative to the slit of spectrograph on the Raman spectral polarization were analyzed and measured experimentally. Circularly polarized laser and the correction of the polarizing angle of Raman signal are necessary to avoid fake results in the measuring of Raman spectral of single-molecule, which was not noticed in initial papers. (c) 2005 Elsevier B.V. All rights reserved.

Single-molecule detection in a liquid by surface-enhanced resonance Raman scattering

Surface-enhanced resonance Raman scattering (SERRS) of Rhodamine 6G (R6G) adsorbed on colloidal silver clusters in a liquid has been studied. The first observation of single molecule resonance Raman scattering in a liquid in a probed volume of 10 pL was achieved. Anisotropy of SERRS spectra of single R6G molecule and huge SERRS spectra were observed and compared with that of single molecule fixed in the dried films of sols, which revealed the intricate complex interaction between R6G molecules and the environment in a liquid.

共焦扫描系统扫描深度与厚度失真分析

采用几何光学方法对共焦系统扫描时产生的扫描深度与厚度失真进行了理论分析，对名义扫描深度与实际扫描深度之间的关系进行了研究．以若丹明6G薄膜与玻片组成的多层样品为模型，对其进行了模拟计算，得到了扫描深度与厚度失真与系统数值孔径、折射率和样品厚度之间的关系．在实验上分别采用单光子荧光和双光子荧光作为检测信号，在反射式共焦扫描系统上进行了纵向扫描实验，并与模拟计算的结果进行了比较和分析．

Optical properties of dye-doped zirconia films by spectroscopic ellipsometry

The optical properties of zirconia films doped with rhodamine 6G and oxazine 725 by the sol-gel process were investigated using spectroscopic ellipsometry (SE). Accurate refractive index n and the extinction coefficient k were determined using a three-oscillator classical Lorentz model in the wavelength range of 300-800 nm. The derived refractive index of dye-doped films exhibited anomalous dispersion in the absorption region. Wavelength tunable output lasing action yellow and near-infrared wavelength region was achieved by DFB configuration using zirconia films doped with R6G and oxazine 725. (c) 2006 Elsevier B.V. All rights reserved.

普通烟草与毛曼陀罗族间体细胞杂交的研究

采用PEG／DMSO融合法，从普通烟草(Nicotiana tabacum L.cv.Xanthi nc)叶肉和毛曼陀罗(Datura innoxia Mill.)茎或叶愈伤组织原生质体融合获得I5株花盆中健康生长的族间体细胞杂种植株;其中11株是在没有选择压力的条件下获得，4株则是在有IOA和R6G选择系统存在下获得。同时获得一株试管开花且形态异常的植株和一株花盆中生长的嵌合植株。lOmM IOA和I5μ g／ml R6G均能分别有效地抑制烟草叶肉和毛曼陀罗愈伤组织原生质体的分裂;10% DMSO能显著提高原生质体融合率;PEG种类并不重要，但浓度则很重要;BAP较ZT，KT对植株分化有更好的诱导效果。杂种的形态、细胞、同工酶、Southern杂交，花粉育性分析结果如下：1、l5株杂种较双亲普遍株型矮小，生长缓慢，形态接近烟草但不很正常，根据形态特征可分为两种类型：(1)共有8株，其叶片大小、形状、颜色、开花习惯、花类型（单花）等均与毛曼陀罗接近，但子房败育;(2)共有7株，其株型、叶片形状、颜色、光滑度、花形状、类型（圆锥状花序）、颜色更接近烟草，但少数杂种开单花或先单花后圆锥状花序或先单花后两种花并存，且开花时间不一，部分子房败育。2、杂种染色体数目大都在60～90之间，个别者较少(48条)或较多(125条)，没有一株为双二倍体(2n=96)，并全部为混倍体。3、15株杂种植株均有双亲的细胞色素氧化酶同工酶特征谱带;大部分都有双亲的过氧化物酶同工酶特征谱带，少都仅具烟草的谱带。4、Hae Ⅲ／水稻rDNA的Southern杂交分析表明杂种1较双亲多一条谱带，杂种2较双亲也多一条弱带，其它杂种尚待定。5、花粉活力测定表明毛曼陀罗（种子再生而来）的为99%，烟草（原生质体再生而来）为80～90%，而杂种的为24～61%，育性普遍低于双亲。

纳米结构的构建与表征

在纳米尺寸上按照人们意愿排列物质分子、原子以及进行材料和分子的剪裁具有重 要的研究意义。本论文利用扫描探针加工技术构建种类、形状、尺寸等可控的纳米结构，并且结合表面增强拉曼光谱，对其进行了表征。同时，发展了一种合成可控形貌半导纳米结构的溶液方法，观察了在溶剂挥发作用下纳米粒子在固一液界面的白组装，这种白组装现象有望实现自然自聚集纳米器件的合成。并且制备了一种高效拉曼活性基底，稳定性和重复性好。1．探针针尖性能对扫描探针刻蚀（SPL）的影响采用四种不同类型的针尖：标准Si3N4针尖、敲击模式刻蚀Si针尖、俄罗斯针尖（末覆涂层的Si针尖）、导电针尖进行扫描探针刻蚀实验。发现针尖性能是刻蚀过程中一个重要的因素。具有较小弹性常数的针尖不易在基底进行图案刻划和粒子的操纵。并且，给出了才目应的机理。2．利用“纳米笔”加工技术（DPN）直接构建纳米结构 罗丹明6G（R6G）是一种重要的激光染料和生物染料。利用“纳米笔”加工技术在新解 离的云母表面获得了R6G分子排列。R6G分子通过静电作用结合在云母表面，并且形 成稳定的R6G纳米结构。通过控制针尖不同的运动方向，在云母上构建了不同形状的R6G纳米结构。同时讨论了针尖运行速度和接触时间对DPN的影响。结合表面增强拉曼散射效应，对这些构建的纳米结构进行了定性验证。聚-L-赖氨酸是一种常用的表面修饰试剂，它可以增强生物分子或细胞与表面间的吸附力。利用OPN技术成功的在云母表面获得了聚-L-赖氨酸纳米结构。通过控制针尖不同的运动方向，在表面构建了不同形状包括方块、线条、点、十字花等纳米图案。这种局 部或特定区域的修饰表面在生物化学传感器或微、纳米排列的实现上具有重要的潜在应用价值。牛血．清白蛋白和小牛胸腺组蛋白都是非常重要的蛋白质分子。利用DPN技术将这些蛋自质分子成功的沉积在云母表面。同时考察了针尖一基底接触时间及针尖运行速度对OPN 的影响。这种蛋白质纳米结构的构建为生物纳米器件的最终实现提供了一条简单而有效的途径。3．ZnO纳米结构可控合成及其在固一液界面的自组装使用一种简单而温和的方法直接在溶液中合成了不同ZnO纳米结构。通过调节水一甲醇比率，分别获得zno纳米线、纳米棒和纳米粒子。获得的这些ZnO纳米结构用AFM、XPS及荧光光谱加以表征。讨论了水一甲醇比率对合成ZnO纳米结构不同形貌的影响，给出了可能的机理。溶剂挥发作用卜，zno纳米粒子在云母和玻璃表面进行白组装。不同条件卜，获得不同形状的自组装排列图案。结合现有理论，给出了合理解释。这种方法可以引导纳米粒子的排列，有望实现白然自聚集纳米器件的合成。4．表面增强拉曼活性基底制备和表征使用CTAB，利用一种简单的方法制备了SERS活性基底，并且呈现很好的拉曼响应。对于R6G的检测浓度可以达到1*10-14M，且稳定性和重复性好。结合重定位技术，获得了银纳米晶、簇和膜的AFM图像，而且获得了单分子R6G在同一聚集位置上的SERS光谱。讨论了增强因子的影响因素，并且给出了合理的机理。

染料激光器混合染料体系的研究

分子间的能量转移是当今光化学、光生物学和光物理学中的一个重要课题，长期以来一直受到人们的广泛关注。六十年代染料激光器出现以后，人们很快就将这一原理应用研究染料激光器的工作物质。选择适当的混合染料溶液作为染料激光器的工作物质，可以提高某些染料的激光输出能量或扩展激光波长覆盖范围，这已成为分子间能量转移的一个新的应用领域。本文首先阐述分子间能量转移的基本理论并对混合染料体系的选择及其研究进行了文献综述。另外，对研究过程中，他人工作改采用的实验手段也进行了概述，特别对荧光寿命的测量讨论得较为仔细。实验中我们着重研究了R6G/Red B、R6G/NB两个二元体系和C440/C540/Saf.~(-1)、C440/Fl.Na/Saf.~(-1)以及R6G/Red B/Ox725三个三元混合染料体系。实验方法主要通过测量混合染料溶液的荧光光谱、荧光寿命和激光输出性能。激发源波长始终固定在337.1nm。荧光光谱和荧光寿命多是在英国Applied Photophysics公司生产的SP-70型纳秒荧光分光光度计上测量的。这套仪器的设置从激发、探测以至最后的数据处理（微机处理）都达到较高的灵敏度和精确度。更为主要的是采用了时间相关单光子计数技术这一新的测量方法，真有较高的时间分辨本领，为染料分子的短寿命测量提供了重复性极好的可靠数据。并且由于这套仪器的信噪比大，能够测出高浓度溶液情况下的荧光光谱，而一般地荧光光谱仪却很难探测。激光调谐范围的测量是在QJD-9型染料激光器上进行的，光路结构安排合理，各项技术指标都达到了较高水平。激光强度的测量是采用了通用的光路结构测量混合染料溶液的超辐射模式的激光输出。下面是我们的实验结果。1.R6G/Red B、R6G/NB二元混合染料体系。通过测量R6G/Red B混合染料溶液的荧光光谱，了解到给体R6G有较强的能量转移给受体Red B。又通过荧光寿命的测量，表明溶液浓度达到～10~(-3) mol.L~(-1)时，分子间的能量转移主要是共振转移，且符合Stern-Volmer关系。由此我们进行了一定量讨论，计算了不同浓度溶液中给体与受体分子间的平均距离R。激光性能的测量表明这一体系具有较大的激光强度输出，且通过改变给体、受体浓度可扩展调谐范围。对于R6G/NB，我们做了类似的研究。但与R6G/Red B不同的是，R6G/NB始终是双峰。激光性能测量表明此体系可以扩展调谐范围，且可改善NB的激光输出，降低泵浦阈值。2.C440/C540/Saf.-T、C440/Fl.Na/Saf.-T及R6G/Red B/Ox725三元体系。C440/C540/Saf.-T混合染料溶液的荧光光谱研究表明，三种染料分子之间有较强的能量转移发生，且与溶液浓度配比适当时，可以同时获得三个不同波段处的荧光发射，从而可望扩展波长调谐范围。见图1。对于C440/Fl.Na/Saf.-T混合溶液，我们主要是采用光谱手段，对能量转移过程做了研究。结果表明C440/Fl.Na之间以辐射转移为主要机制，Fl.Na/Saf.-T之间在波度稍大时，发生共振转移的可能性较强。另外对能量转移过程进行了一些定量的讨论。计算求得C440/Fl.Na的临距离R_o = 47.5A，小于Fl.Na/Saf.-T的临界距离R_o = 59.0A，因而后者发生共振转移的可能性较大。R6G/Red B/Ox725体系与前两体系相比是向长波长方向扩展了。激光性能的测量表明，此体系可以作为染料激光器的工作物质。实验结果还表明三种染料混合以后的激光性能比Red B/Ox725二组份混合的效果好得多。R6G/Red B/Ox725的超辐射是图2所示。

碱性染料杂多酸多元配合物显色反应及其应用的研究

本论文由六部分组成第一部分文献综述，对近年来碱性染料-元素杂多酸显色反应的研究及其应用的进展情况作了介绍。第二部分研究了乙基罗丹明B与硅钼杂多酸 PVA存在下的显色条件，缔合物的最大吸收波长为584nm，在测量波长586nm处，ε_(586) = 3.4 * 10~5lmol·cm~(-1), 缔合物至少可稳定1小时，0～1.3μg Si(IV)/25ml Beer定律，只有P(V)、A(s)、Ge(IV)等离子干扰严重，可采用酒石酸掩蔽之。从而提出了测定硅的高灵敏光度法。本法可不经分离直接用于水样及NaOH、NH_4G、NH_4NO_3等试剂分析，检测下限分别为10ppb(水样,5ml) 1 * 10~(-5)%（试剂，1g）。第三部分研究了乙基罗丹明B-磷钼杂多酸-PVA新的显色体系的光度测定条件，缔合物的最大吸收波长为584nm，在工作波长586nm下，ε_(586) = 3.2 * 10~5l·mol~(-1)·cm~(-1)，配合物至少可稳定1小时，0～1.5μgP(V)/25ml服从Beer定律。藉提高酸度和还原剂以消除Si(IV)、As(V)等离子的干扰。本法可不经分离直接用于钢样及硫酸钠、硫酸镁试剂中痕量磷的测定，检测下限达1 * 10~(-5)%(试剂1g)。第四部分研究了乙基罗丹明B-锗钼杂多酸在PVA存在下的显色条件，缔合物最大吸收波长为584nm，在测量波长588nm下，缔合物的表观摩尔吸光系数ε_(588) = 3.8 * 10~5l·mol~(-1)·cm~(-1)，0～1.5μg Ge(IV)/25ml服从Beer定律，缔合物至少可稳定2小时，仅P(V)、As(V)、 Si(IV)等离子严重干扰。第五部分研究了缔合物的形成机理。我们用摩尔比法，等摩尔连续变化法及摩尔吸光系数对比法分别研究呈溶液或结晶状的缔合物组成比，所得结果一致，即Si(或 P、Ge):ERB=1:4。由红外光谱的研究证明，染料ERB~+的结构未受缔合物形成的影响。ERB~+阳离子与杂多酸阴离子是藉离子链力结合成离子对缔合物，并讨论了本类显色反应的历程。第六部分是罗丹明类碱性染料中取代基对缔合的稳定性及萃取率的影响的研究。对用苯萃取罗丹明类碱性染料-高氯酸缔合物体系，进行了吸收光谱、酸度影响、表现摩尔吸光系数、萃取率和萃取平衡常数的测定实验，各种缔合物的最大吸收波长分别为：BRB, 567nm; ERB, 567nm; R6G, 536nm; RB, 563nm。表观摩尔吸光系数分别为(l·mol~(-1)·cm~(-1):BRB, 9.86 * 10~4; ERB, 8.82*10~4;R6G, 4·0.3 * 10~4。萃取率分别为：BRB, 91.9%, ERB, 79.2%; R6G, 45.7%。萃取平衡常数分别为：BRB, 1.32 * 10~4; ERB, 1.14 * 10~3; R6G, 6.06 * 10~2。并用平衡移动法测定缔合物组成均为1：1。根据上述实验结果，从离子体积、憎水和亲水基、取代基的酸碱性及染料阳离子的正电性等四个方面对染料分子上不同取代基对缔合物稳定性、可萃性和溶解度影响进行了讨论，得到了一些规律性的认识：随着取代基体积增大、憎水基的引入和加重、碱性减弱、染料阳离子正电性的增加，均能使形成缔合物的稳定性和可萃性增加，其增加顺序为BRB > ERB > R6G > RB。