CdTe量子点与罗丹明6G间的荧光共振能量转移机理研究

本文在合成水溶性巯基乙酸修饰的CdTe量子点的基础上,研究了CdTe量子点与罗丹明6G之间的荧光共振能量转移.实验结果表明:构建的CdTe量子点(供体)-罗丹明6G(受体)荧光共振能量转移体系在磷酸盐缓冲溶液中有较好的转移效果.当磷酸缓冲溶液pH值为7.4,NaCl浓度为1.0 mol/L时,构建的CdTe量子点-罗丹...     

CdTe量子点与罗丹明6G荧光共振能量转移体系的构建及机理研究

以巯基乙酸为修饰剂,水相合成不同尺寸的CdTe量子点(QDs),研究不同发射波长的CdTe QDs与罗丹明6G(R6G)之间的荧光共振能量转移(FRET)规律。结果发现,以发射波长为515nm的CdTe QDs为供体与R6G能量转移效率为58.5%,以R6G为供体与发射波长为605nm的CdTe QDs能量转移效率为49.4%,即在CdTe QDs-R6G的FRET体系中,量子点既可作为供体也可作为受体。在此基础上,构建了CdTe QDs(供体)-R6G(第一受体)-CdTe QDs(第二受体)的三元FRET体系,并研究了其双荧光共振能量转移的机理。     

CdTe/CdS-罗丹明荧光共振能量转移猝灭法测定铅(Ⅱ)及相互作用机制的研究

以巯基乙酸为修饰剂,水相合成量子产率高达75％的CdTe/CdS核壳型量子点,建立了以CdTe/CdS QDs作为能量供体,罗丹明B作为能量受体组成的荧光共振能量转移体系.在此基础上,以CdTe/CdS-罗丹明B为荧光探针,荧光共振能量转移猝灭为理论基础,设计出一种检测pb2+含量的方法.在0～9.62×10-11mo...     

CdTe量子点-罗丹明6G荧光共振能量转移体系的构建及其应用研究

采用巯基化合物修饰的CdTe量子点构建了量子点(供体)-罗丹明6G(受体)荧光共振能量转移体系, 研究了CdTe量子点与牛血清白蛋白(BSA)的相互作用. 结果表明, CdTe量子点与BSA相互作用后提高了CdTe量子点-罗丹明6G 体系的荧光共振能量转移(FRET)效率, 减小了CdTe量子点和罗丹明6G分子间的距离(r), 证实BSA是通过其色氨酸(Trp)残基与CdTe量子点表面金属发生配位作用而直接结合到量子点表面的.     

CdS量子点与曙红Y间的荧光共振能量转移研究

在水溶液中,量子点与有机荧光染料之间可能发生荧光共振能量转移(FRET)。本文以发射波长470nm的Cd S量子点为供体,曙红Y为受体,建立了Cd S量子点-曙红Y的FRET体系,研究了该体系的FRET参数。该体系受体供体数目比为8,猝灭效率为45.6%,增强效率为20.1%;供体-受体间的距离为4.4nm;临界能量转移距离为2.4nm。     

CdS量子点与CdSe量子点间荧光共振能量转移研究

在有机相中合成了不同尺寸的CdS和CdSe量子点, 并利用Langmuir-Blodgett (LB)技术将相同尺寸的CdS和CdSe量子点组装成多层复合纳米有序结构. 采用荧光光谱研究了CdS和CdSe量子点在混合体系和多层复合纳米有序结构状态下的荧光共振能量转移(Fluorescence resonance energy transfer, FRET). 我们观察到CdS和CdSe量子点混合溶液与当溶剂挥发形成固态膜中, CdS量子点的荧光强度较溶液状态下强烈猝灭, 表明当颗粒间距离减小时CdS和CdSe量子点间产生较高效率的荧光共振能量转移. 在多层复合纳米有序结构中, 随着给体CdS量子点层数的增加, 单层受体CdSe量子点的荧光逐步增强, 这表明层间纵向能量转移率随给体层数的增加而提高.     

吖啶红-罗丹明B荧光共振能量转移法测定汞

研究了吖啶红(供体)和罗丹明B(受体)之间荧光共振能量转移的最佳条件,建立了荧光共振能量转移猝灭法测定污水和废旧电池中痕量汞的方法。室温中,采用十六烷基三甲基溴化胺(CTMAB),在pH=7.0条件下,吖啶红与罗丹明B之间能产生有效的共振能量转移,汞离子的加入能使体系中罗丹明B荧光峰强猝灭从而测定汞的含量。汞离子浓度在0.05～2.5μg/mL范围内与罗丹明B荧光强度变化ΔF呈现良好线性关系(r=0.9997),检出限(3σ/K)为0.95ng/mL,加标回收率98.0%～104.5%。该方法可用于污水和废旧电池中痕量汞的测定。     

Au@SiO2/LaF3∶Ce,Tb复合结构的发光共振能量转移

发光共振能量转移(LRET)与给体?受体间的距离密切相关,可体现分子间距离的变化,在生命科学领域有着重要的应用. 本文设计并合成了Au@SiO2/LaF3:Ce,Tb复合纳米结构,研究了LaF3:Ce,Tb(给体)与Au纳米颗粒(受体)间的LRET行为. 通过调控SiO2层厚度,可以改变给体?受体之间的距离. 当SiO2层厚度增加到42 nm时,仍能观察到明显的LRET现象. 这一距离远超过通常荧光共振能量转移的有效范围,表明由长发光寿命的稀土发光纳米材料与金纳米颗粒形成的给体?受体对可在更大的距离上实现能量转移.     

量子点-罗丹明B比率型荧光探针的制备与性能

本文采用CdSe/Cd_xZn_(1-x)S核/合金壳量子点(QDs)作为荧光共振能量转移体系(FRET)的供体,通过巯基络合作用在其表面修饰一层L-半胱氨酸(Cys)分子,赋予QDs优异的水溶性能,再通过静电相互作用将罗丹明B(RhB)构筑于QDs-Cys表面,获得了一类新型的水溶性FRET体系.采用荧光光谱分析了pH以及供受体浓度比对FRET能量转移效率的影响.研究结果表明,通过静电结合构筑的QDs-Cys-RhB荧光共振能量转移体系对pH和供受体浓度具有敏感的荧光信号响应性能.当pH从10降到7时,FRET体系的荧光共振能量转移效率由49.39%增加到58.99%;当供受体浓度比为3:1时,FRET体系的能量转移效率高达61.09%.由此可见,通过表面络合与静电相互作用构筑的QDs-Cys-RhB荧光共振能量转移体系具有优异的光信号响应性,可以作为一类灵敏、精确的可调式比率型荧光探针,在生物检测、免疫分子等领域中具有广阔的应用前景.     

基于量子点的荧光共振能量转移

研究了具有相反电荷的两种量子点间的荧光共振能量转移.分别以巯基乙酸(TGA)和十六烷基三甲基溴化胺(CTMAB)修饰发射绿色和红色荧光的CdSe/ZnS量子点,使其由油溶性变为水溶性,且表面带相反的电荷,并对修饰后的水相量子点进行琼脂糖凝胶电泳、荧光成像、量子产率等系列表征.对两种量子点间的荧光共振能量转移现象进行研究.结果表明: 在激发波长为400 nm时,两种量子点在磷酸盐缓冲溶液(pH 7.5)中具有较好的荧光共振能量转移效率(猝灭效率0.54,增强效率0.27).     

Solid-emissive rhodamine: hydrogen bonding-assisted efficient intermolecular fluorescence resonance energy transfer in the solid state

Solid-emissive rhodamine complexes are obtained by mixing commercial rhodamine B (RhB) with the recently developed solid-emissive boron 2-(2′-pyridyl)imidazole (BOPIM) derivatives. The formation of intermolecular hydrogen bonds between RhB and BOPIM dyes plays a key role in the emission of RhB in the solid state. The disappearance of emissions from BOPIM dyes indicates the occurrence of efficient intermolecular fluorescence resonance energy transfer (FRET). The hydrogen bond also helps prevent the intermolecular interaction between the carboxyl moieties on RhB to alleviate concentration-induced fluorescence quenching because the emission of the complexes can be directly lightened by excitation at the RhB absorption (510 nm). Our results indicate that intermolecular FRET assisted by non-covalent interactions can be an efficient tool for constructing red or near-infrared solid emitters.     

Enhancement of electronic excitation energy transfer in the colloidal crystals of colloidal silica suspensions doped with fluorescent dyes

The efficiency of electronic excitation energy transfer from photo-excited rhodamine 110 (Rh110, energy donor) to rhodamine B (RhB, energy acceptor) in an exhaustively deionized colloidal silica suspension has been studied. This colloidal suspension shows Bragg reflection due to the formation of colloidal crystals and the Bragg-peak wavelength is controllable by the volume fraction of the silica spheres. When the Bragg-peak wavelength matches with the fluorescence band of Rh110, a depletion was observed in the Rh110 fluorescence spectrum. This means the fluorescence of Rh110 is partially trapped due to the Bragg reflection inside the crystal lattice. In the coexistence of RhB, the enhancement of RhB fluorescence intensity was observed. These facts clearly indicate the trapped photon energy of Rh110 is efficiently transferred to RhB within the colloidal crystals. The quantitative measurements showed that the enhancement of the transfer efficiency is 20% (or slightly more) in the present experimental conditions.     

Multimodal coupling of optical transitions and plasmonic oscillations in rhodamine B modified gold nanoparticles

The optical properties of a photoluminescent dye rhodamine B (RhB) interacting with gold nanoparticles (AuNP) have been investigated using plasmonic absorbance, fluorescence, and resonance elastic light scattering (RELS) spectroscopy. We have found that these interactions result in a multimodal coupling that influence optical transitions in RhB. In absorbance measurements, we have observed for the first time the coupling resulting in strong screening of RhB π-π* transitions, likely caused by a contact adsorption of RhB on a conductive surface of AuNP. The nanoparticles quench also very efficiently the RhB fluorescence. We have determined that the static quenching mechanism with a non-F?rster fluorescence resonance energy transfer (FRET) from RhB molecules to AuNP is involved. The Stern-Volmer dependence F(0)/F = f(Q) shows an upward deviation from linearity, attributed to the ultra-high quenching efficiency of AuNP leading to the new extended Stern-Volmer model. A sharp RELS peak of RhB alone (λ(max) = 566 nm) has been observed for the first time and attributed to the resonance fluorescence and enhanced scattering. This peak is completely quenched in the presence of AuNP(22nm). Our quantum mechanical calculations confirm that the distance between AuNP surface and conjugated π-electron system in RhB is well within the range of plasmonic fields extending from AuNP. The optical transition coupling to plasmonic oscillations and the efficient energy transfer due to the interactions of fluorescent dyes with nanoparticles are important for biophysical studies of life processes and applications in nanomedicine.     

Energy/Hole Transfer Phenomena in Hybrid α‐Sexithiophene (α‐STH) Nanoparticle–CdTe Quantum‐Dot Nanocomposites

Considerable attention has been paid to hybrid organic–inorganic nanocomposites for designing new optical materials. Herein, we demonstrate the energy and hole transfer of hybrid hole‐transporting α‐sexithiophene (α‐STH) nanoparticle–CdTe quantum dot (QD) nanocomposites using steady‐state and time‐resolved spectroscopy. Absorption and photoluminescence studies confirm the loss of planarity of the α‐sexithiophene molecule due to the formation of polymer nanoparticles. Upon photoexcitation at 370 nm, a nonradiative energy transfer (73 %) occurs from the hole‐transporting α‐STH nanoparticles to the CdTe nanoparticles with a rate of energy transfer of 6.13×10⁹ s^?1. However, photoluminescence quenching of the CdTe QDs in the presence of the hole‐transporting α‐STH nanoparticles is observed at 490 nm excitation, which is due to both static‐quenching and hole‐transfer‐based dynamic‐quenching phenomena. The calculated hole‐transporting rate is 7.13×10⁷ s^?1 in the presence of 42×10^?8 M α‐STH nanoparticles. Our findings suggest that the interest in α‐sexithiophene (α‐STH) nanoparticle–CdTe QD hybrid nanocomposites might grow in the coming years because of various potential applications, such as solar cells, optoelectronic devices, and so on.     

Cadion 1B对CdTe量子点光谱性质的影响

本文研究了水溶液中镉试剂1B对巯基乙酸稳定下CdTe量子点(CdTe QD)荧光和紫外吸收光谱的影响，文中分别考察了表面活性剂、缓冲介质、镉试剂2B用量、pH以及温度的影响。结果表明：镉试剂1B作用于CdTe QD后产生新的可见光谱吸收峰，并对CdTe QD的荧光有猝灭作用，同时借它们之间的作用可实现镉试剂1B对CdTe QD的包覆，表观平衡常数为1.095×106mol·L-1，表面覆盖率达45%。热力学结果显示，镉试剂1B与CdTe QD的作用是一个自发的、熵驱动的过程，其作用力主要表现为静电作用。     

Bio serves nano: biological light-harvesting complex as energy donor for semiconductor quantum dots

Light-harvesting complex (LHCII) of the photosynthetic apparatus in plants is attached to type-II core-shell CdTe/CdSe/ZnS nanocrystals (quantum dots, QD) exhibiting an absorption band at 710 nm and carrying a dihydrolipoic acid coating for water solubility. LHCII stays functional upon binding to the QD surface and enhances the light utilization of the QDs significantly, similar to its light-harvesting function in photosynthesis. Electronic excitation energy transfer of about 50% efficiency is shown by donor (LHCII) fluorescence quenching as well as sensitized acceptor (QD) emission and corroborated by time-resolved fluorescence measurements. The energy transfer efficiency is commensurable with the expected efficiency calculated according to F?rster theory on the basis of the estimated donor-acceptor separation. Light harvesting is particularly efficient in the red spectral domain where QD absorption is relatively low. Excitation over the entire visible spectrum is further improved by complementing the biological pigments in LHCII with a dye attached to the apoprotein; the dye has been chosen to absorb in the "green gap" of the LHCII absorption spectrum and transfers its excitation energy ultimately to QD. This is the first report of a biological light-harvesting complex serving an inorganic semiconductor nanocrystal. Due to the charge separation between the core and the shell in type-II QDs the presented LHCII-QD hybrid complexes are potentially interesting for sensitized charge-transfer and photovoltaic applications.     

Purely organic light-harvesting phosphorescence energy transfer by β-cyclodextrin pseudorotaxane for mitochondria targeted imaging

A new type of purely organic light-harvesting phosphorescence energy transfer (PET) supramolecular assembly is constructed from 4-(4-bromophenyl)-pyridine modified β-cyclodextrin (CD-PY) as a donor, cucurbit[8]uril (CB[8]) as a mediator, rhodamine B (RhB) as an acceptor, and adamantane modified hyaluronic acid (HA-ADA) as a cancer cell targeting agent. Interestingly, the complexation of free CD-PY, which has no RTP emission in aqueous solution, with CB[8] results in the formation of CD-PY@CB[8] pseudorotaxane with an RTP emission at 510 nm. Then the addition of RhB leads to an efficient light-harvesting PET process with highly efficient energy transfer and an ultrahigh antenna effect (36.42) between CD-PY@CB[8] pseudorotaxane and RhB. Importantly, CD-PY@CB[8]@RhB assembles with HA-ADA into nanoparticles with further enhanced delayed emission at 590 nm. The nanoparticles could be successfully used for mitochondria targeted imaging in A549 cancer cells. This aqueous-state PET based on a supramolecular assembly strategy has potential application in delayed fluorescence cell imaging.

A new type of purely organic light-harvesting PET supramolecular assembly is constructed with efficient energy transfer and ultrahigh antenna effect. Moreover, the assembly could be used for mitochondria targeted imaging in A549 cancer cells.     

水相合成CdX (X＝Te, Te/CdS, Te/ZnS)红色量子点及毒性效应

分别以巯基乙酸(Mercaptoacetic Acid, MA)、还原型谷胱甘肽(Glutathione, GSH)为稳定剂在水相中直接合成了巯基乙酸CdTe (CdTe-MA)、红色巯基乙酸CdTe/CdS (CdTe/CdS-MA)、巯基乙酸CdTe/ZnS (CdTe/ZnS-MA)及谷胱甘肽CdTe (CdTe-GSH)量子点. 其中, CdTe-GSH量子点的量子产率可达47.3%. 体外溶血实验证实CdTe/ZnS-MA和CdTe-GSH量子点的溶血率较CdTe-MA和CdTe/CdS-MA低, 浓度为0.05 mmol/L的量子点溶血率＜5%, 达到了生物医用材料的要求. 活体实验证实: 通过尾静脉方式把量子点注入小鼠体内后, 荧光显微镜观察发现高剂量的量子点(0.4 mmol/10 g)在体内主要在心、肝、脾、肾组织中分布较多, 且引起不同程度的组织病变.