Magnetic nanomaterials. Remote nanoactuactors for biomedical applications: Magnetic Hyperthermia, Magnetofection and Drug Delivery

F. H. SÁNCHEZ

Río de Janeiro

Simposio; Simposio Materia; 2016

Universidade Federal de Rio de Janeiro (UFRJ)

Magnetic iron oxides, magnetite and maghemite, are the most important materials for biomedical applications due to their high biocompatibility. Colloids and nanocomposites containing NPs with sizes between 6 and 30 nm are commonly used. NPs in this range of sizes are single domain and have a magnetic moment equivalent of 4.6x103 to 5.7x105 Bohr magnetons. This feature habilitates their remote manipulation with magnetic fields that can be easily realized. Colloids need to be stable at physiological pH, which require their functionalization with a shell that provides electrostatic and/or steric repulsion. Additional functionalization is needed in order to fulfill other tasks. Magnetic hydrogels (or ferrogels) based on PVA are one kind of very interesting materials. NPs can be easily incorporated in elevated mass ratios which confers them a high magnetic response. These materials swell to a considerably larger size by absorption of water solutions and their form and size can be manipulated using external magnetic signals. Therefore, in principle they can perform a number of tasks by remote manipulation. Recent in vitro MH research performed on genetically modified A549 cell cultures internalized with 12 nm Fe3O4@citric_acid NPs helped to elucidate why apoptosis is observed in this type of essays while almost no temperature rise is recorded. In the experiments, modified cells expressed the green fluorescent protein, which should happen when they attain a degree of stress comparable to being heated up to at least 42 °C. Occurrence of this expression may obey to a very localized temperature increase or to a field induced mechanical stress. In this work it was observed that the position of magnetic endosomes changes and that they align with each other and with applied magnetic field, thus giving support to the activation of magneto-mechanic effects. MF is a technique for the treatment of genetic diseases which has been studied during some time.3 Although has been carried out almost exclusively in vitro, it remains a very promising method due to its high potential and extremely low invasiveness. To develop it further, interdisciplinary work must be done in several directions. One important task is to contribute to understand more deeply the underlying physics of the process, which involves the binding of NPs and viral particles to form complexes, the transport of complexes assisted magnetically, and their internalization in target cells.