Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Nanoparticles were obtained by electrostatic complexation between chitosan and gellan gum at different polysaccharide ratios. The effect of the chitosan:gellan ratio on the particle charge and particle size distribution was determined by dynamic light scattering measurements. The particle stability was studied during storage in an aqueous medium at 25 degrees C for 100 h. The effect of the preparation procedure (mixing steps) on the characteristics of the complexes was also determined. In addition, the influence of a nonionic surfactant (polysorbate-20) on the chitosan:gellan electrostatic complexes (PECs) was evaluated. The charge of the PECs depended on the polysaccharide ratio. During storage, structural reorganization of the complexes was observed. The mixture protocol was a determinant factor for PEC size. Multilayered particles formed by a 2-step mixing of polysaccharide solutions showed a considerable increase in size as compared to the complexes formed by a 1-step mixing. The PEC size, count rate and zeta potential were not affected by the presence of polysorbate-20. (C) 2013 Elsevier Ltd. All rights reserved.941695703Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2009/54137-1]CNPq [301869/2006-5]