sepharose and pyrene

Agarose-chitosan-immobilized octadecylsilyl-silica (C

Topics: Chitosan; Chromatography, High Pressure Liquid; Chrysanthemum; Phenanthrenes; Pyrenes; Sepharose; Solid Phase Microextraction

In situ steady-state fluorescence (SSF) measurement technique was applied to investigation of pyrene labeled Poly(vinyl alcohol) (PVA-Py) molecules diffusion in and out of agarose gels. Gel samples with four different concentration of agarose were prepared. PVA-Py was synthesized by "click" chemistry method and dissolved in water to use in diffusion experiments. The results were analyzed by using Fickian type diffusion model, and it was found that sorption and desorption processes of PVA-Py molecules in and out of agarose gel have two distinct regions for short and long diffusion times. Sorption and desorption coefficients were measured and it was seen that the diffusion rates were much larger at short times and at lower agarose concentrations.

Topics: Diffusion; Gels; Polyvinyl Alcohol; Pyrenes; Sepharose; Spectrometry, Fluorescence

The gradient diffusion of ionic sodium dodecyl sulfate micelles in agarose gel was investigated at moderate concentrations above the CMC. Of particular interest were the effects of micelle, gel, and sodium chloride concentration on the micelle diffusivity. Holographic interferometry was used to measure the gradient diffusion coefficient at three sodium chloride concentrations (0, 0.03, 0.10 M), three gel concentrations (0, 1, 2 wt%), and several surfactant concentrations. Time-resolved fluorescence quenching was used to measure aggregation numbers both in solution and gel. The micelle diffusivity increased linearly with surfactant concentration at the two larger sodium chloride concentrations and all gel concentrations. In general, the strength of this effect increased with decreasing sodium chloride concentration and increased with gel concentration. This behavior is evidence of decreasing micelle-micelle electrostatic interactions with increasing sodium chloride concentrations, and increasing excluded volume effects and hydrodynamic screening with increasing gel concentration, respectively. The only exception was at 0.1M sodium chloride and 2 wt% agarose, which showed a slight reduction in the slope compared to 1 wt% agarose. It was found that the concentration effect is quite strong for charged solutes: at a NaCl concentration of 0.03 M in a 2% agarose gel, in a solution with 3% SDS micelles by volume, the micelle diffusion coefficient is doubled relative to its value in the same gel at infinite dilution. The extrapolated, infinite-dilution diffusion coefficients and the rate at which the micelle diffusivity increased with surfactant concentration were compared with predictions of previously published theories in which the micelles are treated as charged, colloidal spheres and the gel as a Brinkman medium. The experimental data and theoretical predictions were in good agreement.

Topics: Diffusion; Gels; Hydrodynamics; Interferometry; Ions; Micelles; Models, Theoretical; Pyrenes; Sepharose; Sodium Chloride; Sodium Dodecyl Sulfate; Solutions; Spectrometry, Fluorescence; Static Electricity

A pyrene-labeled Zn²+-cyclen complex for the staining of DNA in agarose gels is reported. The metal chelate coordinates reversibly to the DNA phosphate backbone, which induces the formation of pyrene excimers. The typical pyrene excimer emission is used for the detection of the DNA. Staining is limited to agarose gels and is less sensitive than ethidium bromide, but DNA amounts as low as 10 ng and short DNA strands (∼300 b.p.) are detectable. Gel extraction as a standard technique in molecular biology was successfully performed after staining with Zn²+-cyclen-pyrene. Cytotoxicity tests on HeLa and V-79 cells reveal that the zinc-cyclen pyrene probe is significant less toxic compared to ethidium bromide.

Topics: Animals; Chelating Agents; Cricetinae; Cyclams; DNA; Fluorescent Dyes; Gels; HeLa Cells; Heterocyclic Compounds; Humans; Models, Molecular; Molecular Conformation; Pyrenes; Sepharose; Solubility; Staining and Labeling; Water; Zinc

Agarose hydrogels which constitute a special class of soft matter are undoubtedly one of the most studied biopolymer gels. However, certain issues such as why the sulfate salts and sulfate content in the agarose molecules reduce the gel strength are still not very clear. The present work provides a detailed analysis of structural changes with respect to coil-helix transition or aggregation of helices in the aqueous agarose solutions and hydrogels that accompanied the systematic addition of sodium sulfate. A combined approach which includes the differential scanning calorimetry and temperature-dependent vacuum-ultraviolet circular dichroism measurements permitted the accurate estimates of the energy changes for coil-helix transition and helix-helix interactions. The hydration process of agarose molecule investigated from differential scanning calorimetry and concentration-dependent ultrasonic measurements indicated the loss of both the freeze bound and nonfreezable water molecules with the increase of sulfate content in the solution. Temperature-dependent fluorescence measurements using pyrene as a probe indicated polarity changes when the gel network is created in waters of different salt concentration. Changes in the hydrogen bonding of the water molecules confined in the gel network have been monitored from the intensity ratios of ice-like and liquid-like -OH stretching band of water Fourier transform infrared (FTIR) spectra. Analysis of the -OH stretching band showed the strengthening of hydrogen bonding of water molecules in the gel which tend to weaken with the subsequent addition of sodium sulfate.

Topics: Calorimetry, Differential Scanning; Circular Dichroism; Gels; Pyrenes; Sepharose; Spectroscopy, Fourier Transform Infrared; Sulfates; Temperature; Thermodynamics; Water