Production and characterization of thermoresponsive magnetic membranes

• Autor(a) principal: Lavadinho, João Pedro Sequeira
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/90936
• topic: Magnetic hyperthermia; superparamagnetic nanoparticles; polyacrylamide; thermoresponsive; magnetic nanocomposites; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

In the last years, the electrospinning technique has proven to be very advantageous to produce polymeric membranes since it originates nanometric fibres with a high surface area/volume ratio. As a result, electrospun nanofibers have been used for different biomedical applications, particularly in the development of multifunctional devices. To increase membrane functionality additional materials such as magnetic nanoparticles (MNPs) that respond to external stimuli can be combined with electrospun fibres. The incorporation of these nanoparticles into electrospun fibres produces a multifunctional system that can be used for cancer theranostic applications. The main objective of this work was to process a thermoresponsive polymer, polyacrylamide (PAAm), using electrospinning and to incorporate MNPs by their addition to the precursor solution. These membranes will have the ability to respond to two different external stimuli, magnetic field and temperature, being suitable for magnetic hyperthermia application. In the first phase, an optimization study of the electrospinning parameters was made to obtain monodisperse fibres of PAAm. MNPs were synthesized by chemical precipitation technique and then stabilized with oleic acid or dimercaptosuccinic acid to avoid their aggregation. Later the MNPs were added to the precursor polymeric solution and composite membranes were produced, which were characterized in terms of its mechanical properties, and swelling ability. They were also analysed in terms of morphology, chemical properties and structurally by SEM, FTIR and XRD, respectively. PAAm fibres with an average diameter of around 200 nm containing iron oxide nanoparticles were produced. This was confirmed by TEM and EDS analysis showing the presence of NPs and iron in the fibres, respectively. The incorporation of MNPs provided fibre reinforcement by increasing the Young’s modulus. Through magnetic hyperthermia measurements, it was possible to obtain a temperature variation of 1.1ºC, demonstrating the potential of this dual-stimuli responsive membranes for magnetic hyperthermia applications.