Multicolor super-resolution fluorescence imaging via multi-parameter fluorophore detection

Understanding the complexity of the cellular environment will benefit from the ability to unambiguously resolve multiple cellular components, simultaneously and with nanometer-scale spatial resolution. Multicolor super-resolution fluorescence microscopy techniques have been developed to achieve this goal, yet challenges remain in terms of the number of targets that can be simultaneously imaged and the crosstalk between color channels. Herein, we demonstrate multicolor stochastic optical reconstruction microscopy (STORM) based on a multi-parameter detection strategy, which uses both the fluorescence activation wavelength and the emission color to discriminate between photo-activatable fluorescent probes. First, we obtained two-color super-resolution images using the near-infrared cyanine dye Alexa 750 in conjunction with a red cyanine dye Alexa 647, and quantified color crosstalk levels and image registration accuracy. Combinatorial pairing of these two switchable dyes with fluorophores which enhance photo-activation enabled multi-parameter detection of six different probes. Using this approach, we obtained six-color super-resolution fluorescence images of a model sample. The combination of multiple fluorescence detection parameters for improved fluorophore discrimination promises to substantially enhance our ability to visualize multiple cellular targets with sub-diffraction-limit resolution.     

Intramolecular Charge Transfer (ICT) Based Two-photon Fluorescent Probe for Bisulfite with Bioimaging Applications

Abstract

A two-photon fluorescent probe has been adopted for bisulfite based on an intramolecular charge transfer (ICT) mechanism. The fluorescence intensity of the probe decreased by 837 fold following treatment with HSO₃^? and the detection limit was 42?nM. This probe showed excellent properties such as high photostability, good two-photon properties, and large Stokes shifts. More importantly, this approach offers a rapid, highly selective, and sensitive method to determine HSO₃^? in buffer solutions and real samples. Furthermore, the probe was successfully used for two-photon fluorescence visualization of trace SO₂ derivatives in biological systems.     

New Fluorometric Method for Continuous Measurement of ß-Cyanoalanine Synthase Activity

Abstract

A new method for the determination of injectase has been described. Assay conditions have been established which permit the assay of injectase over the range from 10^?3 to 0. 1 unit. The method is simple, rapid, sensitive, and reliable.     

Spectrometry: Spectrofluorimetric Study of Benzo[a]Quinolizidines as Potential Fluorescent Probes for DNA

Abstract

The interaction between DNA and several benzo[a]quinolizidines, including emetine and four synthetic benzo[a]quinolizidine derivatives, has been studied using spectrophotometric and spectrofluorimetric techniques. An appreciable decrease in molar absorptivity at the maxima at λ = 230 nm and λ = 280 nm is observed when increasing DNA concentrations (10 mg/ml-100 mg/ml) are added to aqueous buffered solutions (pH = 7) of the benzo[a]quinolizidine derivatives. These compounds exhibit native fluorescence at 315 nm (λex = 285 nm), which is quenched by increasing amounts of DNA. The interaction between DNA and benzo[a]quinolizidines was confirmed by viscosimetry. Increases between 1.9% and 10.8% in the reduced specific viscosity (n/no) of DNA solutions were observed due to the presence of the benzo[a]quinolizidines studied.     

一种近红外发射荧光探针的合成及其荧光增强识别Hg2+

汞离子(Hg~(2+))由于高毒性以及容易对环境和人体造成损害,其检测越来越受到人们的重视。本文基于4-(二乙氨基)水杨醛设计合成了一种近红外发射荧光探针L,该探针可在MeCN/HEPES(体积比2/8,pH=7.4)缓冲溶液中高选择性地荧光增强识别Hg~(2+),其具有合成简便、抗干扰能力强、适用pH范围宽等特点。进一步研究表明,探针L可用于真实水样中Hg~(2+)的检测。     

一维双链4-氧-1(4H)-吡啶氮乙酸桥联铜配位聚合物[Cu(4-OPA)2]n的合成、结构及性能研究

A novel coordination polymer of [Cu(4-OPA)₂]_n (4-OPA^-=4-oxo-1(4H)-pyridineacetate anion) was synthesized and characterized by elemental analysis, IR, TG, fluorescence and X-ray single crystal diffraction. The title complex crystallizes in triclinic with space group P1, a=0.713 17(14) nm, b=0.739 81(15) nm, c=0.753 02(15) nm, α=91.46(3)°, β=109.14(3)°, γ=111.31(3)°. V=0.344 92(17) nm³, Z=1, R=0.028 6, wR=0.080 3. The Cu atom occupies an inversion site in an octahedral environment, defined by two carbonyl O atoms and four carboxyl O atoms from different 4-OPA^- ligands. Adjacent Cu(Ⅱ) atoms are bridged by the 4-OPA^- ligands, forming a one-dimensional double chain structure. The closest Cu…Cu distance is 0.850 6(3) nm. The results of TG and fluorescent analysis show that the title coordination polymer is stable under 262.8 ℃ and has two emission peaks at 422 and 484 nm. CCDC: 287038.     

A Platform for Preparation of Monodispersed Fluorescent Conjugated Polymer Microspheres with Core‐Shell Structures

A strategy to prepare stable monodispersed fluorescent microspheres is developed by modifying the Wessling method to synthesize poly(p‐phenylenevinylene) (PPV) on the surface of a highly crosslinked polymer core. The positively charged PPV polymer precursors (pre‐PPV) are adsorbed onto the core with negative charges on the surface and then the insoluble fluorescent PPVs form after thermal elimination. Each individual sphere is found to possess a very smooth surface with an even distribution of fluorescence by microscopic techniques. Very small coefficient of variance (CV) values of emission intensity (<4.0%) and size (<2.3%) are realized for microspheres prepared in the same batch. The spheres are demonstrated to have good thermal stability and photostability.