染料分子吸附在正、负电性纳米银上的荧光增强及荧光猝灭现象

制备了两种不同表面电性的胶态纳米银,选取阴离子型染料分子荧光素钠、既有阴离子基团又有阳离子的染料分子罗丹明B,研究其在两种纳米银表面的荧光增强及荧光猝灭现象.当罗丹明B(RhB)分子分别吸附在这两种纳米银上时,对负电性纳米银,观察到荧光猝灭、荧光峰红移现象,且在分子的浓度适当时,加入KBr可获得较强的表面增强拉曼光谱;在正电性纳米银上,当分子的浓度较大时观察到荧光猝灭,当分子的浓度较小时观察到荧光增强.而当荧光素钠分子( FS)分别吸附在这两种纳米银上时,在负电性纳米银,观察到荧光猝灭;在正电性纳米银上观察荧光急剧增强现象.从分子的结构及纳米银表面局域场增强或无辐射通道的增加对增强和猝灭的原因作了讨论.     

纳米银对表面吸附镝配合物的荧光增强效应研究

研究了不同粒径的纳米银对镝配合物(乙二胺四乙酸配合物)的光谱学性质影响。当配合物溶液的pH值范围为4.0～6.0时,加入纳米银,可观察到大量的纳米银聚集体形成,而在吸收光谱的长波处出现一个新的吸收峰,随着纳米银浓度的增加,该吸收峰逐渐红移,同时,镝配合物的荧光强度增强。实验结果表明,纳米银粒子对镝配合物的荧光增强效应及荧光增强因子与纳米银粒子的浓度和粒径密切相关。随着纳米银浓度的增加,配合物的荧光强度先增强而后又逐渐降低。小粒径的纳米银对镝配合物的荧光增强因子较小。本文从纳米银粒子的聚集效应、局部电磁场增强效应及光吸收效应等方面探讨了纳米银对表面吸附镝配合物的+荧光增强效应机理。     

纳米银粒子对[Ru(bpy)_3]~(2+)光谱学性质的影响及电解质效应

研究了[Ru(bpy)3]2+溶液中引入纳米银粒子的光谱学性质变化规律以及[Ru(bpy)3]2+与纳米银粒子所构成的溶液体系([Ru(bpy)3]2+-Ag)的电解质效应.研究结果表明,[Ru(bpy)3]2+吸附在纳米银粒子表面使纳米银粒子相互桥连形成规则的类链状网络聚集体.纳米银粒子造成[Ru(bpy)3]2+溶液荧光猝灭,且大尺寸的纳米银粒子引起的荧光猝灭程度较大.在[Ru(bpy)3]2+-Ag体系中引入电解质造成纳米银粒子不同程度的聚集和生长.电解质对纳米银聚集影响为:CaCl2MgCl2Ca(NO3)2KClKNO3.随着[Ru(bpy)3]2+-Ag体系中引入电解质含量的增加,溶液的荧光强度先降低而后又逐渐增强,直至达到定值,表明一定量的电解质可产生荧光猝灭释放效应.电解质对荧光强度影响顺序为:Ca(NO3)2CaCl2MgCl2KClKNO3.采用透射电子显微镜、紫外-可见吸收分光光度计和荧光分光光度计等手段从分子间相互作用和能量传输等方面初步探讨了纳米银粒子对表面吸附[Ru(bpy)3]2+溶液光谱学性质的影响机制以及电解质效应.     

二维Bi2Se3晶体对罗丹明6G分子的荧光猝灭效应研究

首次研究了拓扑绝缘体Bi₂Se₃二维晶体对其表面吸附的罗丹明6G分子的荧光猝灭效应, 证明薄层Bi₂Se₃可以有效猝灭罗丹明6G分子的荧光, 且随Bi₂Se₃二维晶体的厚度从单层增加到8层, 荧光猝灭效应增强, 并初步探讨了其荧光猝灭机理.     

纳米银对铕配合物荧光性质的影响(英文)

研究了纳米银对稀土铕-吡啶-2,6-二羧酸配合物(Eu(Ⅲ)C7H5NO4,Eu(Ⅲ)DPA)的荧光性质的影响。随着纳米银浓度增加,荧光强度先增强而后逐渐下降。较大粒径的纳米银使Eu(Ⅲ)DPA荧光增强效率较大,且达到最大荧光增强效率所需的纳米银浓度较低。在高浓度Eu(Ⅲ)DPA溶液体系中,纳米银导致荧光猝灭。电偶极子跃迁发射荧光增强效率大于磁偶极子跃迁发射荧光增强效率。分析认为,纳米银对Eu(Ⅲ)DPA荧光性质的影响与表面等离子体共振与激发态荧光中心强烈耦合以及表面等离子体再吸收有关。同时,纳米银对铕配合物的不对称率有影响,其影响因素与局域电磁场增强,折射率以及配位场有关。     

纳米银对铕配合物荧光性质的影响

本文研究了纳米银对稀土铕-吡啶-2,6-二羧酸配合物（Eu（Ⅲ）C₇H₅NO₄,Eu（Ⅲ）DPA）的荧光性质的影响。随着纳米银浓度增加,荧光强度先增强而后逐渐下降。较大粒径的纳米银使Eu（Ⅲ）DPA荧光增强效率较大,且达到最大荧光增强效率所需的纳米银浓度较低。在高浓度Eu（Ⅲ）DPA溶液体系中,纳米银导致荧光猝灭。电偶极子跃迁发射荧光增强效率大于磁偶极子跃迁发射荧光增强效率。分析认为,纳米银对Eu（Ⅲ）DPA荧光性质的影响与表面等离子体共振与激发态荧光中心强烈耦合以及表面等离子体再吸收有关。同时,纳米银对铕配合物的不对称率有影响,其影响因素与局域电磁场增强,折射率以及配位场有关。     

CdTe量子点与蛋白质相互作用的荧光猝灭效应

本文在水热法合成水溶性CdTe及核壳结构CdTe/CdS量子点的基础上,分别研究了细胞色素c对CdTe量子点及CdTe/CdS核壳量子点荧光的猝灭效应和CdTe量子点对牛血清白蛋白荧光的猝灭效应,并阐述了猝灭机理。结果显示,细胞色素c对CdTe量子点的荧光猝灭效应具有一定的粒径依赖性,粒径越小,猝灭效应越强;细胞色素c对CdTe/CdS核壳量子点的猝灭效应比对CdTe量子点的更强,揭示了受激电子的表面传递机理。CdTe量子点通过松散牛血清白蛋白的螺旋结构而猝灭其荧光。     

厚朴酚在乙醇中的荧光自猝灭及猝灭机理

系统研究了厚朴酚的荧光光谱和吸收光谱随浓度的变化, 揭示了厚朴酚具有较强的自猝灭特性. 其猝灭包括静态和动态机制: 随着浓度增加, 厚朴酚发生聚集; 同时, 单体和聚集体对荧光的猝灭表现为动态猝灭, 由单体、二聚体、三聚体造成的荧光猝灭速率常数kqm、k qd、k qt值远大于扩散控制的荧光猝灭速率常数. 说明除扩散控制的短程能量转移引起的猝灭外, 厚朴酚还存在长程能量转移导致的猝灭机制.     

吖啶红荧光猝灭法测定痕量硒

在稀盐酸溶液中,Se(Ⅳ)与碘化钾反应生成碘分子,碘分子与吖啶红反应,使其发生荧光猝灭反应,荧光猝灭值在一定范围内与硒(Ⅳ)浓度呈线性关系,据此建立了测定痕量硒的荧光猝灭方法。方法的测定范围为0.01～O.20μg·ml-1。方法用于金属锰中痕量硒的测定,结果满意。     

一个新的荧光猝灭动力学方程

从光化学反应动力学模型出发，推导出一个新的荧光猝灭动力学方程：实验结果表明：该方程能够准确地拟合荧光反应的实验数据，可用于定量描述猝灭剂对高分子半透膜内的荧光分子的影响，并能很好地说明荧光猝灭的机理．     

HAS-硅钨杂多酸缔合纳米微粒体系的荧光猝灭

人血清白蛋白;瑞利散射;HAS-硅钨杂多酸缔合纳米微粒体系的荧光猝灭     

纳米金对荧光素的荧光增效作用

纳米金对荧光素的荧光效率具有增强作用,其增强效果取决于纳米金的尺寸大小和浓度。粒径分别为5、15、25 nm的纳米金与不同浓度的荧光素溶液作用后可以增强荧光强度3~10倍,同时讨论了溶液环境和pH值对荧光增强的影响。采用本实验提出的方法可以在生化检测方面提高荧光检测方法的灵敏度。     

纳米银胶体颗粒制备新方法及其荧光增强效应研究

在纳米银胶体颗粒的制备中引入固相分散基体——天然纤维素,利用其表面丰富的羟基、醚基等含氧基团,均匀吸附银离子后,浸入低浓度硼氢化钠,经历脱附、还原过程生成银纳米颗粒的胶体溶液.与经典制备方法相比,反应过程温和且无需添加任何稳定剂,所制得的银纳米颗粒细小、均一、稳定性高.荧光增强实验表明,由于消除了大分子稳定剂的阻碍,胶体溶液在较低浓度下即可获得很好的荧光增强作用.     

纳米银碗阵列结构的高效制备及荧光增强性能

报道了一种以自组装单层聚苯乙烯纳米微球阵列为模板, 通过真空热蒸镀银纳米粒子高效制备大面积银碗阵列结构的方法. 测试结果表明, 制得的银碗阵列结构为微纳米复合分级结构, 银碗由平均粒径为10 nm的银纳米粒子组成. 紫外-可见吸收光谱测试结果表明, 银碗阵列结构表面具有银纳米粒子的局域表面等离子体共振吸收峰. 将荧光分子N,N'-二正丁基喹吖啶酮(DBQA)分别蒸镀到普通银膜和银碗阵列结构表面并测试了荧光光谱. 结果表明, 在银碗阵列结构表面的荧光分子强度得到了显著增强, 说明制备的银碗阵列结构是优良的荧光增强基底.     

Phthalocyanine macrocycle as stabilizer for gold and silver nanoparticles

A one-step process was used for the preparation of gold and silver nanoparticles stabilized by an aminophthalocyanine macrocycle. The resultant nanoparticles were characterized by absorption spectra, infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The nanoparticles were found to possess relatively narrow size distribution. The gold nanoparticles have an average diameter of ~2 nm, while silver particles have 4–5 nm. Preliminary studies on fluorescence and surface enhanced Raman spectroscopy were carried out using these nanoparticles. Fluorescence studies indicate that gold nanoparticles do not quench the fluorescence, while silver nanoparticles do. The stabilized nanoparticles showed enhancement of the Raman signals, thus revealing that they are good substrates for surface enhanced Raman scattering studies.     

Ultrasonic-Assisted Synthesis of Monodisperse Ag Nanoparticles and Their Applications in Surface Enhanced Raman Scattering and Fluorescence Enhancement

Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine (OAm) and oleic acid (OA). The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum (SERS) property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.     

A close analysis of metal-enhanced fluorescence of tryptophan induced by silver nanoparticles: wavelength emission dependence

In the last few years, silver nanoparticles have been proposed as a promising alternative for the label-free detection of proteins via metal-enhanced fluorescence. Generally, the aromatic amino acid tryptophan is most frequently used in this type of studies, because the intrinsic fluorescence of proteins is usually dominated by tryptophan emissions. In the present study, we evaluated the fluorescence behavior of tryptophan in the presence of a silver colloid with nanoparticles of 100 nm in diameter. The results showed that a nanoparticles concentration of 32 mg L^?1 induced maximum fluorescence enhancement. However, the metal-enhanced fluorescence was dependent on the emission wavelength of tryptophan, and this phenomenon was closely related to the metal surface reabsorption process (inner filter effect), suggesting that the plasmon resonance reabsorption effect should be taken into account in analyses involving protein studies by metal-enhanced fluorescence.     

Unmodified "GNP-oligonucleotide" nanobiohybrids: a simple route for emission enhancement of DNA intercalators

We present herein a simple method for enhancing the emission of DNA intercalators in homogeneous nanobiohybrids of unlabeled oligonucleotides and unmodified gold nanoparticles (GNPs). Pristine single‐stranded DNA (ss‐DNA) has been wrapped around unmodified GNPs to induce metal‐enhanced fluorescence (MEF) of DNA intercalators, such as ethidium bromide and propidium iodide. The thickness of the ss‐DNA layer on the gold nanosurface determines the extent of MEF, since this depends on the position of the intercalator in relation to the metal surface. Presumably, at a suitable thickness of this DNA layer, more of the intercalator is localized at the optimum distance from the nanoparticle to give rise to MEF. Importantly, no external spacer or coating agent was needed to induce the MEF effect of the GNPs. The concentration ratios of Au to DNA in the nanohybrids, as well as the capping agents applied to the GNPs, play key roles in enhancing the emission of the intercalators. The dimensions of both components of the nanobiohybrids, that is, the size of the GNPs and the length of the oligonucleotide, have considerable influences on the emission enhancement of the intercalators. Emission intensity increased with increasing size of the GNPs and length of the oligonucleotide only when the DNA efficiently wrapped the nanoparticles. An almost 100 % increment in the quantum yield of ethidium bromide was achieved with the GNP–DNA nanobiohybrid compared with that with DNA alone (in the absence of GNP), and the fluorescence emission was enhanced by 50 % even at an oligonucleotide concentration of 2 nM . The plasmonic effect of the GNPs in the emission enhancement was also established by the use of similar nanobioconjugates of ss‐DNA with nonmetallic carbon nanoparticles and TiO₂ nanoparticles, with which no increase in the fluorescence emission of ethidium bromide was observed.