**4. Conclusions**

Modified polyol method was used in the chemical synthesis of potassium strontium niobate ferroelectric oxide with stoichiometry KSr2Nb5O15 and of nickel zinc ferrite paramagnetic oxide, stoichiometry Ni0, 5Zn0, 5Fe2O4. Single-phase ceramic phases with average crystallite size in nanometric scale were obtained. Using XRD and AFM essays, average crystallite size and particle surface parameters could be determined, mainly. We employed a method for the preparation of functional composites and nanocomposites based on vulcanized natural rubber, grounded in the dry mixing of the constituents using a open chamber mixing. A vulcanization system based on sulfur (S8), suitable for natural rubber and ceramic nanoparticles was used. The development of a potential application for composites and nanocomposites based on vulcanized natural rubber was started and the preliminary results are encouraging, namely: use of paramagnetic and ferroelectric nanocomposites as modulating agents of the develop‐ ment of colonies of *Leishmania braziliensis* parasites.
