No abstract

Resumo: O estudo de sistemas envolvendo nanopartículas de óxido de ferro e polianilina vem ganhando importância nos últimos anos. Entre esses trabalhos, ainda há um pequeno número de pesquisas que abordam o efeito da sonicação sobre o preparo desses híbridos. Assim, o presente trabalho teve como objetivo avaliar o efeito da sonicação sobre as propriedades de nanopartículas de maghemita revestidas com polianilina, via planejamento fatorial. Os materiais obtidos foram estudados por espectroscopia no infravermelho, difração de raios X e por análise termogravimétrica. As amostras também tiveram a resistividade elétrica e a força magnética investigadas. Os resultados obtidos demonstram que o aumento da potência de sonicação é capaz de produzir um considerável aumento da extensão do grau de dopagem, associado com a diminuição da resistividade das amostras. Por outro lado, a mesma potência de sonicação produziu a destruição de grande parte da maghemita presente, levando a menores forças magnéticas. Palavras-chave: Dispersão ultrassônica, polimerização in situ, planejamento experimental. Preparation of Maghemite and Polyaniline Nanocomposites Assisted by UltrasoundAbstract: The study of systems constituted by iron oxide nanoparticles and polyaniline has increased in the last years. However, few studies are related to the sonication effect on the preparation of these hybrid materials. In this work the effect of sonication on the properties of maghemite/polyaniline hybrids was studied using experimental design techniques. The materials obtained were studied by infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. Samples were also characterized by measuring the electric resistivity and by magnetic force tests. Obtained results show that the increase of the sonication power produces the increase of the doping process and the decrease of the electrical resistivity. The same sonication power produced the destruction of a large amount of the maghemite, leading to lower magnetic forces.

This paper presents the main aspects regarding the production of biodegradable microspheres, the optimization of parameters in the drug encapsulation process, the techniques available for polymeric systems sterilization and the effects of γ-irradiation on microparticles.

Oxaliplatin and modified magnetic nanoparticles (magnetite‐lysine) are inserted into microspheres of previously synthesized poly(lactic acid‐co‐glycolic acid‐b‐ethylene glycol) PLGA‐PEG to evaluate the in vitro hyperthermal potential and the acute toxicity in mice. The used nanoparticles are synthesized by the coprecipitation method, using Fe II and Fe III, and modification with lysine is performed during the synthesis. The drug and the magnetic nanoparticles are inserted into the polymer beads through oil in water (O/W) emulsion. The obtained composites are then characterized by Fourier‐transform infrared (FTIR), Thermogravimetric analysis (TGA), X‐ray Diffraction (XRD), and submitted to magnetic hyperthermia and acute toxicity tests. The hyperthermia tests are conducted according to an experimental design. The magnetite‐lysine nanoparticles reached the temperature for the desired application and are able to raise the temperature by 6 °C at the higher investigated current, time, and concentration conditions. According to the proposed statistical study, only the test time exerted significant positive influence on the observed temperature increase, although synergies between time and concentration and between current and concentration are also significant. In vivo acute toxicity tests are also conducted with swiss mice and revealed that the prepared materials and procedures can be regarded as safe and of low toxicity.

a This paper has been partially presented at the 16th Brazilian Polymer Congress, held on-line, 24-28/Oct/2021.