Polysaccharide stabilized nanoparticles as potential drug carriers

Many drug molecules are sparingly soluble in water which can severely limit their pharmacological potential. Attaching such drugs to water soluble polymer carriers can increase their solubility. In addition, attaching drug molecules to high molecular mass carriers (e.g., polymers) can alter their in vivo distribution; potentially leading, e.g., to a more selective distribution towards tumors rather than normal tissues. We have developed strategies to synthesize nanoparticles (Au, Ag, other metals, binary salts) using naturally-occurring polysaccharides (chondroitin sulfate, xylan, dextran, gum Arabic) as the stabilizing agents. The polysaccharides used are water soluble resulting in polysaccharide/nanoparticle combinations that readily disperse in water. The potential for these polysaccharide-stabilized nanoparticles to serve as drug carriers was evaluated by studying the binding of various dyes or fluorophores as model compounds to these polysaccharide-stabilized nanoparticles. The non-covalent interactions between the dye or fluorophore and the polysaccharide/nanoparticle combination leads to changes in the UV/Vis spectrum or in the intensity of the emitted fluorescence; an effect that can be exploited to determine whether the dye or fluorophore molecules are free or bound to the nanoparticle/polysaccharide combination. Other strategies we explored involved the covalent attachment of a model compound to the polysaccharide before or after the synthesis of the NP. Size exclusion chromatography, a chromatographic technique that separates molecules based upon their hydrodynamic volume, was used to determine whether the model compounds were free in solution or bound to the polysaccharide/nanoparticle combination