A feasible approach to tune the interaction of chitosan with sodium dodecyl sulfate

Interaction of binary chitosan/nonionic surfactant (NIS) system with sodium dodecyl sulfate (SDS) in aqueous solution is described using turbodimetry, light scattering, electophoretic mobility and cryogenic electron microscopy. The formation of insoluble CHI/SDS complexes is weakened with a decrease in molecular weight of chitosan and critical micelle concentration of NIS as well as with an increase in NIS concentration. Soluble chitosan/NIS complexes absorb SDS molecules until the charge of mixed chitosan/NIS/SDS complexes reaches a critical value that depends on chitosan molecular weight followed by aggregation of primary electrostatic complexes via hydrogen bonding to complex nanoparticles. In contrast to formation of asymmetric swarm-like structures in the binary chitosan/SDS system, the aggregation of complex nanoparticles in the ternary chitosan/NIS/SDS system occurs by a head-to-tail binding mechanism with formation of elongated filamentous microstructures. The finding can be promising for preparation of microbiologically stable pharmaceutical and cosmetic compositions and drug delivery systems containing mixed surfactants. [Display omitted] •Interaction of chitosan (CHI)/nonionic surfactant (NIS) system with SDS is described.•CHI/NIS binary system is less sensitive to SDS than CHI alone.•In the presence of NIS, longer CHI molecules form complexes with SDS faster.•A decrease in critical micelle concentration of NIS decreases the interaction.•CHI/NIS/SDS complexes associate forming elongated filamentous microstructures.