RESUMO
Processes for nanoparticle synthesis often use toxic solvents under aggressive conditions. A greener alternative is the burning of self-organized alginate systems. We followed the influence of the CaCl2 concentrations during gelation of sodium alginate and the heating rate on the synthesis of nanoparticles by the combustion method using TGA as a reactor vessel. Samples were collected after each main process of mass loss and characterized using the Scanning Electron Microscopy, Infrared Spectroscopy, and X-ray Diffraction. Samples treated at 50⯰C·min-1 presented porous structures at temperatures more than 500⯰C lower than the treatments at 10⯰C·min-1. All calcium alginate samples presented changing from a predominantly amorphous to crystalline structures such as Ca(OH)2, CaCO3 in the calcite phase and CaO as a function of the temperature, while sodium alginate produced mainly Na2CO3, NaOH and NaO. We observed two main correlations: 1) between the porosity and the heating rate, and 2) between the formation of crystalline structure in intermediate temperatures and the CaCl2 concentration in the gelation step.
Assuntos
Alginatos/química , Compostos de Cálcio/química , Cálcio/química , Nanopartículas/química , Óxidos/química , Técnicas de Química Sintética , Química Verde , Análise Espectral , Temperatura , TermogravimetriaRESUMO
American tegumentary leishmaniasis (ATL) is considered a neglected disease, for which an effective vaccine or an efficient diagnosis is not yet available and whose chemotherapeutic arsenal is threatened by the emergence of resistance by etiological agents such as Leishmania amazonensis. ATL is endemic in poor countries and has a high incidence in Brazil. Vaccines developed from native parasite fractions have led to the identification of defined antigenic subunits and the development of vaccine adjuvant technology. The purpose of the present study was to develop and compare preparations based on membrane antigens from L. amazonensis, as a biotechnological prototype for the immunoprophylaxis of the disease in a murine experimental model. For this purpose, batches of biodegradable polymeric micro/nanoparticles were produced, characterized and compared with other parasite's antigens in solution. All preparations containing membrane antigens presented low toxicity on murine macrophages. The in vivo evaluation of immunization efficacy was performed against a challenge with L. amazonensis, along with an evaluation of the immune response profile generated in BALB/C mice. The animals were followed for sample processing and quantification of serum-specific cytokines, nitrites and antibodies. The sera of animals immunized with the non-encapsulated antigen formulations showed higher intensities of nitrites and total IgGs. This approach evidenced the importance of the biological studies involving the immune response of the host against the parasite being interconnected and related to the subfractionation of its proteins in the search for more effective vaccine candidates.