Bis azo dye liquid crystalline micelles as possible drug carriers in immunotargeting technique

Lyotropic liquid crystal mesophases, represented in this work by Congo Red bis azo dye solution, were proposed as systems to carry drugs to immuno-selected targets. The possible use of Congo Red for this aim arises from its liquid crystalline features, enabling it to attach to immune complexes as polymolecular, ordered conglomerates and simultaneously to incorporate many organic compounds into its mesophase, largely independent of the water with a specific but adaptive molecular organization. Molecules with planar rigid structure, and/or large hydrophobic fragments, especially those with a positively charged group in the molecule, are found to be incorporated best. Rhodamine B, Rhodamine 6G and adriamycine, which have the assumed binding features, were tested as model compounds and were found to be readily engaged into Congo Red mesophase. The effect of hydrophobicity on ligand binding was evaluated following the incorporation of homologic 10, 12, 14, 16 carbon chain organic acids and the effect of charge using small mobile tandem molecules of pI differing by a few pH units (lysine-norleucine, tyrosine-tyramine). Positive charge seems to affect binding especially by influencing the organization of molecules and the shape of the micelle simultaneously. Congo Red immobilized to heat-aggregated immunoglobulins and antibodies in the immune complex was found to retain its binding ability, confirming its possible usefulness for drug transport.