Complexes of 1-alkyl-4-aza-1-azoniabicyclo[2.2.2]octane bromides with lanthanum nitrate: Aggregation and interaction with biomolecules

Abstract

Aggregation of new multifunctional amphiphilic complexes of 1-alkyl-4-aza-1-azoniabicyclo[2.2.2]octane bromides (Alk = CnH2n+1, n = 14, 16, 18) with lanthanum nitrate, their solubilization activity and complexation ability toward biopolyanions, as well as antimicrobial properties have been studied to establish the influence of the structure of these compounds on the functional activity. The critical micelle concentration, aggregation numbers and size characteristics of metallosurfactant in aqueous solutions, complexation of metallosurfactants with oligonucleotide, DNA and bovine serum albumin (BSA) have been determined by fluorescence spectroscopy, spectrophotometry, dynamic and electrophoretic light scattering, and circular dichroism techniques. The results have been compared with the properties of metal-free surfactant (ligand), as well as the composition of ligand with inorganic salt. Beneficial effect of the metallosurfactants hydrophobicity on the solubilizing ability of metallomicellar solutions with respect to the water-insoluble dye Orange OT and the high complexing ability of metallomicelles with respect to the DNA decamer (oligonucleotide), DNA and BSA have been established. Metallocomplex bearing hexadecyl ligand effectively interacted with BSA and bound to the tryptophan amino acid residue of the polypeptide.