荧光染料吖啶红作测定蛋白质的生物探针——蛋白质的染料分析法新进展

简述染料结合分析法的发展过程,吖啶红染料自取和体系测定蛋白质的最佳试验条件和测定结果。阳离子荧光染料吖淀红及其自聚的二聚体的可平衡转化,形成自聚平衡体系,在表面活性剂十二烷基磺酸钠的存在下,蛋白质的定量加入可调节这一平衡,从而引起体系 荧光有规律的变化。方法线性范围宽、灵敏度高、反应速度快、准确度高 、抗干扰 能力强,是染料分析法定量测定蛋白质的最新方法之一。     

蛋白质测定的流动注射荧光法

根据荧光素的单体－二聚体平衡转化的原理，提出了一种检测蛋白质的方法；荧光素在表面活性剂作用下形成二聚体后荧光强度明显降低，加入蛋白质后二聚体解聚使荧光强度增加；结合流动注射法测定牛血清蛋白（BSA），该法简便，灵敏度高，对血清中蛋白质进行测定，结果令人满意。     

光谱法与共焦荧光成像法研究罗丹明B与ct-DNA的相互作用

采用吸收光谱、荧光光谱以及共焦荧光成像技术研究生理条件下罗丹明B(Rhodamine B,RB)与小牛胸腺DNA(ct-DNA)的相互作用以及相互作用模式。光谱研究结果显示,在450~650 nm的吸收光谱范围内,ct-DNA溶液对罗丹明B有减色作用;在560~660 nm荧光发射光谱范围内,ct-DNA对罗丹明B有荧光猝灭作用。同时,随着ct-DNA的加入,罗丹明B溶液的荧光偏振值发生变化,说明罗丹明B与ct-DNA能发生相互作用。在竞争性实验中,罗丹明B未能将亚甲基蓝(MB)从MB-ct-DNA复合体系中置换出来,说明罗丹明B与ct-DNA通过沟槽结合方式发生相互作用。共焦荧光成像结果显示,ct-DNA加入后,罗丹明B的荧光猝灭十分明显。利用罗丹明B和4',6-二脒基-2-苯基吲哚(DAPI)对He La细胞染色后进行共焦荧光成像,结果进一步证实罗丹明B与ct-DNA是通过沟槽结合作用将细胞核染成红色。     

罗丹明6G的溶液状态和荧光特性的研究

罗丹明6G的荧光性质和它的分子聚集态研究是一个重要的科研领域,所得之k_d值表明水溶液中形成罗丹明6G的双聚体。本文提出用荧光法测定k_d聚合常数,该法用于测定罗丹明6G的溶液状态.实验结果表明罗丹明6G双聚体解聚的某些规律,当单体与双聚体平衡趋于单体时,荧光灵敏度就会增加。     

含罗丹明B基团的聚天冬酰胺荧光成像探针研究

以L-天冬氨酸为原料,在体积分数为85%的磷酸催化条件下采用热缩合方法合成了聚琥珀酰亚胺大分子,用罗丹明B与乙二胺反应生成的罗丹明-乙二胺衍生物的氨基以及乙醇胺上的氨基对聚琥珀酰亚胺进行开环反应,合成了含罗丹明B基团的聚天冬酰胺大分子.通过溴化与亲核取代反应将磺胺嘧啶基团接枝于聚天冬酰胺大分子上,从而制备具有肿瘤靶向功能的水溶性聚天冬酰胺大分子荧光探针(SD-PHEA-RhB).对所合成的荧光探针进行了核磁共振谱、红外光谱、紫外-可见光谱、凝胶渗透色谱和质谱等结构表征,进一步测试了其分子量及分布、粒径、荧光性能、体外细胞毒性与细胞摄取以及荧光成像性能.实验结果表明,所合成的聚天冬酰胺荧光成像探针具有良好的水溶性和荧光性能,对酸性环境敏感,对Hep G2和HeLa细胞均具有较低的体外细胞毒性,能被HeLa肿瘤细胞选择性摄取,且能获得较好的HeLa细胞红色荧光成像.     

荧光偏振发射平台法及其应用

本文从原理上叙述荧光偏振发射平台法,并用荧光单体-单体混合物及单体-聚合物体系进行验证试验。前者如荧光黄-罗丹明S(或四碘荧光素、或罗丹明B),后者如罗丹明6G-罗丹明6G聚合物体系,结果满意。     

金纳米颗粒表面能量转移及巯基化合物的检测

二氧化硅稳定的金纳米颗粒(Au-SiO₂)与罗丹明B之间发生表面能量转移,使罗丹明B荧光猝灭。 金纳米颗粒对罗丹明B的Stern-Volmer猝灭常数为4.3×10³ L/mol。 当荧光猝灭的混合体系中加入巯基化合物时,巯基化合物与金纳米颗粒发生强相互作用阻断罗丹明B-金纳米颗粒之间的能量转移,罗丹明B荧光恢复。 基于罗丹明B-Au-SiO₂体系对巯基化合物的单一响应,建立了一种简单快速检测巯基化合物的方法;并且由于二氧化硅对金纳米颗粒的稳定作用,金纳米颗粒成为一种可以回收利用的检测探针。     

吖啶橙—罗丹明6G—罗丹明B组合成各种混合染料体系的能量转移研究

本文对吖啶橙－罗丹明６Ｇ－罗丹明Ｂ组合成各种混合染料体系的能量转移进行了研究。结果表明，在十二烷基硫酸钠的水溶液中，吖啶橙－罗丹明６Ｇ间，罗丹明６Ｇ－；罗丹明Ｂ间，吖啶橙－罗丹明Ｂ间均能发生有效的能量转移。可以认为不仅染料单体，而且二聚体也是能量转移效率的竞争，探讨了表面活性剂对能量转移的影响。本文的工作将有助于拓宽能量转移的理论研究和应用范围。     

三维荧光光谱的应用研究

本文通过实验探讨了三维荧光光谱在罗丹明B研究中的应用,结果显示,罗丹明B(RhB)三维荧光光谱图较二维荧光光谱图能更详细地描述被测组分的部分性质,可为综合考查罗丹明B的结构特征提供参考。文中还对近年来三维荧光光谱分析技术在不同领域中的应用做了简要介绍。     

I-3-丁基罗丹明B缔合微粒体系的光谱特性

I -丁基罗丹明B缔合微粒体系的光谱特性;I2; 丁基罗丹明B; 缔合纳米微粒; 荧光猝灭; 共振散射; 痕量分析     

Study on the formation and depolymerization of acridine orange dimer in acridine orange-sodium dodecyl benzene sulfonate-protein system

Experiment indicates that the fluorescence of acridine orange (AO) can be greatly quenched by anionic surfactant sodium dodecyl benzene sulfonate (SDBS), but when protein is added into the AO-SDBS system, the fluorescence intensity of the latter is enhanced. It is considered that SDBS can promote the formation of AO dimer, resulting in the quenching of the fluorescence of AO. When bovine serum albumin (BSA) is added into AO-SDBS system, BSA and SDBS can interact and form negative micelle-like cluster complex with "aromatic ring stacking," which destroys the formation conditions of AO dimer and makes some AO dimers turn into monomer, resulting in the fluorescence enhancement of AO-SDBS system. Whereas the positive AO and residual AO dimer are dissolved in the negative BSA-SDBS cluster through electrostatic and hydrophobic forces and form a large association. Here, the fluorescence enhancement of AO-SDBS is considered to originate from the hydrophobic microenvironment provided by BSA and SDBS, the depolymerization of AO dimer and intermolecular energy transfer between BSA and AO.     

Monitoring protein interactions in the living cell through the fluorescence decays of the cyan fluorescent protein.

Using fluorescence lifetime microspectroscopy and imaging techniques, we have studied the fluorescence of cyan fluorescent protein (CFP) transiently expressed in HEK-293 cells, in the presence or absence of its fluorescence resonance energy transfer (FRET) partner, yellow fluorescent protein (YFP). When the two proteins are attached through a 27-amino-acid linker, a 33 % average efficiency of intramolecular energy transfer is accurately determined inside the cell. Additionally, we observe a systematic quenching of the CFP fluorescence with increasing levels of protein expression. This quenching cannot be accounted for by formation of the previously described dimer of GFP-related proteins, since its magnitude is unchanged when the fluorescent proteins carry the mutation A206K shown to dissociate this dimer in vitro. Even when the intracellular protein concentration largely exceeds the in vitro dissociation constant of the dimer, self-association remains undetectable, either between free proteins or intramolecularly within the CFP-YFP construct. Instead, the detailed concentration effects are satisfactorily accounted for by a model of intermolecular, concentration-dependent energy transfer, arising from molecular proximity and crowding. In the case of CFP alone, we suggest that self-quenching could result from a pseudo-homo FRET mechanism between different, spectrally shifted emissive forms of the protein. These phenomena require careful consideration in intracellular FRET studies.     

Fluorescence of amphotericin B-deoxycholate (fungizone) monomers and aggregates and the effect of heat-treatment

Fluorescence excitation and emission spectra are reported for the polyene macrolide antifungal agent Amphotericin B formulated as micellar dispersion Fungizone (FZ) and its modified counterpart heat-treated Fungizone. The addition of sodium dodecyl sulfate or sodium deoxycholate surfactant to modulate the aggregation state of Amphotericin B confirms that the monomer and dimer states have different fluorescence spectra. Energy transfer from excited dimer to monomer is observed. Both FZ and heat-treated FZ (HTFZ) show expected S1 --> S0 fluorescence emission as well as anti-Kasha fluorescence emission from the S2 state. The excitation and S1 --> S0 emission spectra of HTFZ are similar to those of FZ, while the S2 --> S0 fluorescence differs in intensity between them. The variation in the rate constant for internal conversion from S2 to S1 as the surfactant concentration is increased differs for FZ and HTFZ; we propose that this may form a new basis for examining the super-aggregated character of AmB preparations. FZ and HTFZ have a similar stability to disaggregation by added sodium dodecyl sulfate surfactant. These findings provide the groundwork for future fluorescence characterization of FZ or HTFZ interactions with cell membranes.     

Sensitive, label-free protein assay using 1-ethyl-3-methylimidazolium tetrafluoroborate-supported microchip electrophoresis with laser-induced fluorescence detection

Based on the dimer-monomer equilibrium movement of the fluorescent dye Pyronin Y (PY), a rapid, simple, highly sensitive, label-free method for protein detection was developed by microchip electrophoresis with LIF detection. PY formed a nonfluorescent dimer induced by the premicellar aggregation of an anionic surfactant, SDS, however, the fluorescence intensity of the system increased dramatically when proteins such as BSA, bovine hemoglobin, cytochrome c, and trypsin were added to the solution due to the transition of dimer to fluorescent monomer. Furthermore, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) instead of PBS was applied as running buffers in microchip electrophoresis. Due to the excellent properties of EMImBF4, not only nonspecific protein adsorption was more efficiently suppressed, but also approximately ten-fold higher fluorescence intensity enhancement was obtained than that using PBS. Under the optimal conditions, detection limits for BSA, bovine hemoglobin, cytochrome c, and trypsin were 1.00x10(-6), 2x10(-6), 7x10(-7), and 5x10(-7) mg/mL, respectively. Thus, without covalent modification of the protein, a protein assay method with high sensitivity was achieved on microchips.     

一种近红外花菁染料的合成及其应用于生物大分子的测定

光谱性质;蛋白质;核酸测定;一种近红外花菁染料的合成及其应用于生物大分子的测定     

Quantum mechanical study of potential energy curves of protons in hydrogen bonds of 7-azaindole dimer in the ground and excited states

Potential curves for simultaneous movement of protons in H-bonds in the ground and first excited states of the 7-azaindole dimer were calculated by the Rein-Harris method. They provide a necessary condition for the fluorescence of the dimer from its rare tautomeric form, confirmation of a postulated potential curve, and an interpretation of experimental results.     

CARBOXYLATED ZINC-PHTHALOCYANINE, INFLUENCE OF DIMERIZATION ON THE SPECTROSCOPIC PROPERTIES. AN ABSORPTION, EMISSION, AND THERMAL LENSING STUDY

Monomer and dimer absorption and emission spectra, and dimerization constants are reported for the diamide of the zinc-tetracarboxyphthalocyanine in pure dimethylformamide (DMF) and in H₂O/DMF mixtures at room temperature. The dimerization constant increases steadily with the water content. The monomer absorption Q-band is insensitive to the solvent composition, whereas dimer spectra show great variations with the water content. Stationary emission measurements show that fluorescence originates exclusively from the monomers. The fluorescence spectrum as well as its absolute fluorescence quantum yield, measured by steady-state thermal lensing, are also insensitive to the solvent composition. The thermal lensing method is discussed for the case of two absorbing species in equilibrium.     

Hydrogen bond-induced vibronic mode mixing in benzoic acid dimer: a laser-induced fluorescence study

Laser-induced dispersed fluorescence spectra of benzoic acid dimer in the cold environment of supersonic jet expansion have been reinvestigated with improved spectral resolution of measurements. The spectra are analyzed with the aid of the normal mode vibrations of the dimer calculated by the ab initio quantum chemistry method at the DFT/B3LYP/6-311+G(*) (*) level of theory. The analysis reveals that the low-frequency intermolecular hydrogen bond modes are mixed extensively with the carboxyl as well as aromatic ring vibrations upon electronic excitation. The mode mixing is manifested as the complete loss of mirror symmetry relation between the fluorescence excitation and dispersed fluorescence spectra of the S(1) origin, and appearance of large number of cross-sequence transitions when the DF spectra are measured by exciting the low-energy vibrations near the S(1) origin. The cross-sequence bands are found in all the cases to be the combinations of two nontotally symmetric fundamentals consisting of one of the intermolecular hydrogen bond modes and the other from the aromatic ring and carboxyl group vibrations. The implications of this mode mixing on the excited state dynamics of the dimer are discussed.