Fluorescence detection and quantitation of recombinant proteins containing oligohistidine tag sequences directly in sodium dodecyl sulfate-polyacrylamide gels

Two fluorophore-nitrilotriacetic acid conjugates, Pro-Q Sapphire 365 and Pro-Q Sapphire 488 oligohistidine gel stains, have been developed for the fluorescence detection of fusion proteins containing oligohistidine tags directly in sodium dodecyl sulfate polyacrylamide gels, without the requirement for electroblotting, reporter enzymes or secondary detection reagents. Pro-Q Sapphire 365 oligohistidine gel stain exhibits bright-blue fluorescence (emission maximum = 450 nm) when illuminated with UV-A or UV-B light from a standard ultraviolet transilluminator. Pro-Q Sapphire 488 oligohistidine gel stain exhibits bright-green fluorescence (emission maximum = 515 nm) when illuminated with visible light from a laser-based gel scanner equipped with a 470 nm second-harmonic generation (SHG) or 488 nm argon-ion laser source. Typically, 25-65 ng of oligohistidine-tagged fusion protein in whole cell lysates is detectable using either stain. After documenting the fluorescence signal from the Pro-Q Sapphire dyes, gels may be post-stained with the red-fluorescent SYPRO Ruby protein gel stain in order to reveal the total protein pattern.     

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.     

Three-way-output response system by electric potential: UV-vis, CD, and fluorescence spectral changes upon electrolysis of the chiral ester of tetracyanoanthraquinodimethane

The newly prepared tetracyanoanthraquinodimethane (TCNAQ) derivatives 1a,b with a chiral auxiliary are good electron acceptors and exhibit weak circular dichroism (CD) based on the absorption of TCNAQ. The twin-type electron acceptor 1c with two TCNAQ units shows larger ellipticity by exciton coupling. UV-vis, CD, and fluorescence spectra were changed drastically upon electrochemical reduction of 1c, which demonstrates the unprecedented three-way-output response system.     

铽(Ⅲ)-1,4-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)丁二酮-[1,4]体系荧光性质的研究及应用

本文研究了Tb(Ⅲ)-1,4-双(′-苯基-3′-甲基-5′-氧代吡唑-4′-基)丁二酮-[1,4](BPMPBD)-溴化十六烷基三甲胺(CTMAB)体系的荧光性质,探讨了响影体系荧光性质的诸因素,确定了最佳实验条件。该体系中Tb(Ⅲ)浓度以2.0×10~(-5)～1.0×10~(-10)mol/L范围内与其荧光强度呈线性关系,检测限可达到5.0×10~(-11)mol/L。应用于合成样品中微量Tb(Ⅲ)的分析,结果令人满意。     

2，4，6－三苯基氧鎓盐分子内旋转受阻对其发光行为的影响

研究了４－位苯基取代基旋转受阻和旋转自由的２，４，６－三苯基氧盐的光物理性质。实验结果表明，当４－位苯基取代基旋转受阻时，氧盐化合物在激发态时引起的分子内极化程度比４－位取代基旋转自由的氧盐化合物大，即在激发态时旋转受阻氧盐化合物发生的分子内电荷转移能力较强；４－位取代基旋转自由的化合物的荧光量子产率随溶剂粘度的增大而有所增大，但旋转受阻化合物在相同的条件下则出现相反的结果。实验结果还表明，４－位取代苯基旋转受阻对化合物的荧光发射不利。     

Synthesis of novel copoly(styrene-maleic anhydride) materials and their luminescent properties

Two series of new high fluorescent polymeric materials based on copoly(styrene-maleic anhydride) (SMA) were prepared by the condensation of SMA with fluorescent groups. One series consists of 1,8-naphthalimides derivatives that are linked with SMA. The other series were prepared by the condensation of SMA with 3,4,9,10-perylene tetracarboxylic mono-anhydride mono-imide. These simple routes to copolymer of styrene and maleic anhydride containing pendent luminescent moiety are promising in increasing fluorescent quantum yield in solid state and processing, in which styrene is employed as “diluents”. The luminescent and the preliminary photovoltaic properties of these copolymers have been investigated.     

Size of Micelles Determined by Static Fluorescence Quenching

We developed a new method to measure the average aggregation number of large rod-like micelles using static fluorescence self-quenching of a solubilized fluorophore. The method is based on the increase of self-quenching of micelle-solubilized pyrene through excimer formation. We consider the effect of random distribution of pyrene in micelles and the micellar size distribution. The measured average aggregation <n> _M is based on a new M-weighted raging similar to our exponential-weighted averaging in the transient decay method. We apply this method to study the effect of a large concentration of salt on the average aggregation behavior of sodium dodecyl sulfate (SDS) and cetyle tetraammonium bromide (CTAB). The sizes increase with increasing ionic concentrations. For SDS, we used the thermodynamic model developed by Missel et al. to calculate < n > _M which we compare with experimental results.