Structural studies on the interaction of CTAB with alginate: Possibility of surfactant therapy with chemo sensitization effect.

The present study reports the preparation of sodium alginate-cetyltrimethylammonium bromide (CTAB) nanoparticles (SANPs) through the interaction of a fixed concentration of alginate (0.2% w/v in water) with two different concentrations of CTAB i.e., below (0.4 mM) and above (1.2 mM) critical micelle concentration (CMC) and the elucidation of its structure on the basis of dynamic light scattering, transmission electron microscopy, small angle neutron scattering and zeta potential measurements. The results indicated that the concentration of CTAB dictated the hydrodynamic shape and size of SANPs. While both the micellized (> CMC) and monomeric forms (< CMC) of CTAB resulted in the formation of negatively charged near spherical particles, the SANPs containing micellized form of CTAB exhibited smaller and more compact hydrodynamic structure compared to those containing monomeric form of CTAB. The cytotoxicity studies involving cancerous cell lines (A549 and L132) indicated that the anticancer activity of CTAB was retained in the SANPs. Subsequently, encapsulation of doxorubicin (DOX), a potent anticancer drug in to SANPs enhanced the efficacy of the overall nano-formulation for effectively killing A549 and L132 cells. Additionally, the DOX loaded SANPs also exhibited the sustained and pH dependent drug release under reservoir-sink model. Together, polyelectrolyte complexation between alginate and CTAB appears as a novel strategy to design nano formulation exhibiting anticancer activity perse as well as for sensitizing the efficacy of chemotherapeutic drugs.