RESUMO
The development of a nanoparticulate system for the carrier antigen is now an important tool in the vaccination process, since a smaller number of doses is necessary for effective immunization. Thus, in this work a nanoparticulate system using polymers of chitosan and poly (methacrylic acid) (CS-PMAA) to adsorb the Vi antigen of Salmonella Typhi was developed. CS-PMAA nanoparticles with different proportions of chitosan and poly (methacrylic acid) were obtained and reached sizes from 123.9 ± 2.48 to 234.9 ± 2.66 nm, and spherical shapes were seen in transmission microscopy. At pH 7.2, the nanoparticles had a cationic surface charge that contributed to the adsorption of the Vi antigen. Qualitative analyses of the isolated Vi antigen were performed using Fourier-transform infrared spectroscopy, which indicated the presence of all the characteristic bands of the capsular polysaccharide, and nuclear magnetic resonance, which showed signals for the five hydrogens and the N-acetyl and O-acetyl groups which are characteristic of the Vi antigen structure. In the adsorption kinetics study, the Vi capsular antigen, contained in a phosphate buffer solution of pH 7.2, experienced 55% adsorption on the 1-1% (CS-PMAA) nanoparticles. The adsorption kinetics results showed the ability of the nanoparticulate system to adsorb the Vi antigen.
RESUMO
Chitosan has attracted much interest due to its special physical and chemical properties related to drug administration. Nanoparticles delivery systems from Vi Antigen are a promising approach in the struggle against typhoid fever. In this paper, we reported the obtainment and the characterization of Vi Antigen by Infrared spectroscopy as well as Molecular Modeling and Computational Chemistry studies of the Chitosan-Vi Antigen interaction through theoretical models. The results of the theoretical and experimental Infrared spectroscopy showed important bands related to N-Acetyl and O-Acetyl groups present in Vi Antigen. Important interactions related to its adsorption were observed through three-dimensional optimized structures. Two models were proposed for the Chitosan-Vi Antigen in adsorption system, one as a monomer and another as an optimized tetrasaccharide antigen. The Molecular Modeling studies presented the best conformation and binding site on the nanoparticle Chitosan-Vi Antigen in models proposed. Interactions were observed between O-Acetyl and N-Acetyl groups the Vi Antigen and hydroxy, amino and methyl groups the Chitosan.
