Specific adsorption of metachromatic compounds of chondroitin sulfate by insoluble calcium salts

A comparative study of polyelectrolyte induced metachromasy

The interaction of two cationic dyes, namely crystal violet (CV), with anionic polyelectrolytes, namely sodium carrageenate (NaCar) and sodium heparinate (NaHep), has been investigated by spectrophotometric method. The polymers induced metachromasy in the dye resulting in the shift of the absorption maxima of the dyes towards shorter wavelengths. The stability of the complexes formed between crystal violet and sodium carrageenate was found to be greater than that formed between crystal violet and sodium heparinate. This fact was further confirmed by reversal studies using alcohols, urea surfactants and electrolytes. The interaction parameters revealed that binding between crystal violet and sodium carrageenate was mainly due to electrostatic interaction while that between crystal violet and sodium heparinate is found to involve both electrostatic and hydrophobic forces.

A study of interaction of cationic dyes with anionic polyelectrolytes

The interactions of Acridine Orange with Sodium Alginate and Pinacyanol Chloride with Heparin have been investigated by spectrophotometric method. The polymers induce metachromasy in the dye as evidenced from the considerable blue shift in the absorption maxima of the corresponding dyes. The interaction constant and thermodynamic parameters of polymer-dye interactions have been determined. The effect of additives such as alcohols, and urea on the reversal of metachromasy has been studied. The data has been used to determine the stability of the metachromatic complex and the nature of binding. The thermodynamic parameters of interaction revealed that binding between Acridine Orange and Sodium Alginate involved only electrostatic forces while that between Pinacyanol Chloride involved both electrostatic and hydrophobic forces. The reversal studies using surfactants indicated the involvement of both electrostatic and hydrophobic forces in binding. Based on the results it can be concluded that Pinacyanol Chloride is more effective inducing metachromasy than Acridine Orange.

A comparative study of polyelectrolyte-dye interactions

The interaction of Azure B with sodium alginate and heparin in aqueous solution has been studied by spectrophotometric method. Absorbance of Azure B at 645 nm decreases and a new band appeared at 545 nm and at 556 nm respectively which indicated that a new metachromatic complex formed. A linear decrease in absorbance is noted. It was found that sodium alginate is more effective than heparin in decreasing the absorbance of Azure B at 645 nm. The stoichiometry of sodium alginate or heparin with Azure B was determined by spectrophotometry. The results suggested that the interaction between Azure B with sodium alginate or heparin was a result of electrostatic forces and the difference between heparin and sodium alginate were attributed to the different negative charge number on repetitive disaccharides unit. Studies on the effect of alcohol or urea indicated that sodium alginate and heparin interacted with the aggregates of Azure B. Thermodynamic parameters of interaction has been evaluated to determine the stability of the metachromatic complex. The effect of surfactants on reversal of metachromasy has also been studied.

INTERCELLULAR MACROMOLECULES CONTAINING POLYSACCHARIDES

A survey is presented of the carbohydrate of intercellular spaces that is known to exist in the form of polysaccharide. This amounts to considering the polysaccharides made by connective tissue cells. The chemical structures of these polysaccharides are discussed in the cases in which they are known and regularities in patterns are noted. Such regularities make of these polysaccharides a natural group that may be related to the natural group of connective tissue cells that produce them. Viscosity is discussed as an important property of hyaluronate. The polyelectrolyte properties of these polysaccharides are considered in detail mainly from the point of view of their use in studying the polysaccharides, fractionating them, and accounting for their behavior in tissues. Polyelectrolyte properties are considered in connection with simple cations, micellar detergent cations, metachromatic dye cations, and protein cations. The existence of the polysaccharides in native tissues as compounds with proteins is discussed in detail, and with particular reference to the two cases most thoroughly studied, the chondroitin sulfate of cartilage and the hyaluronate of synovial fluid. A sharp distinction is drawn between compact and diffuse macromolecules by a contrast of tropocollagen and hyaluronate. The known proteinpolysaccharides of intercellular space are diffuse molecules. Experiments are described to show how hyaluronate hinders sedimentation, excludes compact macromolecules, or entangles with fibrils. Binding of water by connective tissue and elasticity of cartilage may be related to the tissue content of such diffuse macromolecules.

Spectral characteristics of metachromatically stained cartilage: effects of enzymatic degradation and dehydration

When a microspectrophotometer was used to study cartilage, stained metachromatically with Azure A and Safranin O, the following 3 points were made: 1. the absorption maximum of stained cartilage matrix is identical to that reported for solutions of these dyes containing chondroitin sulfate; 2. partial enzymatic degradation of the cartilage matrix has no effect on the position of the absorption peak (although the intensity is greatly diminished); 3. ethanolic dehydration shifts the absorption peak somewhat toward the orthochromatic position, and decreases the intensity of the stain.