, 2005, Huo et al., 2005, Xie et al., 2007 and Zhu et al., 2007). The experimental data demonstrate that cross-linked chitosan nanoparticles were successfully obtained using the established

parameters for ionic gelation method. The best-optimized conditions lead to obtaining nanoparticles smaller than 200 nm for all formulations, with a very suitable particle size distribution and polydispersity appropriate parameters. In the spectrum of chitosan nanoparticles prepared with TPP addition, after the conjugation reaction with TPP, at 1538 cm-1 the formation of new amide bonds by ionic interactions with TPP can be evidenced (Papadimitriou et al., 2008 and Xu check details and Du, 2003). So we can suppose that the tripolyphosphoric groups of TPP are linked with ammonium group of chitosan, the inter- and intramolecular actions learn more are enhanced in chitosan nanoparticles. The T. serrulatus was loaded inside cross-linked nanoparticles with success. The encapsulation efficiency demonstrated levels greater than 90% for all formulations. This high encapsulation efficiency can be explained because the venom is dissolved in TTP solution and at the moment of cross-linked nanoparticle formation, these protein molecules are

completely trapped inside the polymeric matrix of chitosan nanoparticles ( Gan and Wang, 2007). Moreover, the electrostatic interactions

between positively charged groups of chitosan and negatively charged proteins are frequent ( Gan et al., 2005) during the formation of nanoparticles. These interactions were confirmed by potential zeta analysis, in which the increment of protein loading leads to a decrease in the positive charge on the particle surface (Table 1). The particle size reduction observed for the particles containing T. serrulatus occurred possibly due to the steric barrier caused by the presence of protein, which reduces the formation of cross-linking between chitosan and TTP and consequently the formation of smaller particles. Phosphoribosylglycinamide formyltransferase The experimental mice were vaccinated with the adjuvant chitosan nanoparticles and aluminum hydroxide associated experimental group, or not associated control group, with the T. serrulatus venom. When compared to conventional adjuvant aluminum hydroxide, the chitosan nanoparticles in the same venom concentration 10% did not show significant difference in the antibody production. This data proved that chitosan nanoparticles can be equipotent to aluminum hydroxide in antibody production. The control group vaccinated with chitosan nanoparticles or aluminum hydroxide without venom did not present significant antibody production.