Engineering of hybrid composite systems based on nanocellulose and magnetic nanoparticles for biomedical applications

Nowadays an increasing number of people survive cancer, still the incidence and related deaths continue to increase over the years. Current cancer therapies like radiation and chemotherapy cause several negative side effects that significantly affect the patient’s wellbeing. In alternative, magnetic hyperthermia induces a temperature increase in tumor cells due to the application of an alternating magnetic field. This rise in temperature is enough to trigger a set of mechanisms that induce the death of the cancerous cells, which are more sensitive to temperature, without harming healthy cells. The goal of this thesis was to produce a new biomaterial for magnetic hyperthermia application based on two materials: the well-reported heat-inducer Fe3O4 superparamagnetic nanoparticles; and cellulose nanocrystals (CNCs), an effective green mechanical reinforcement. Thus, a new composite material using polyvinyl alcohol (PVA) as a matrix was produced combining the two above-mentioned materials. Two types of structures were produced depending on the crosslinker used: films with citric acid, and hydrogels with glutaraldehyde. The physicochemical properties, as well as structural properties, were evaluated by XRD and FTIR. Additionally, swelling ability and mechanical properties were assessed with water uptake and compression tests. Finally, in vitro tests were made to evaluate the performance of these composite materials. Both films and hydrogels were able to respond to a permanent magnet, absorbed their weight in water, and presented promising mechanical properties. PVA, PVA/CNC, and PVA/CNC/NP hydrogels displayed a compressive modulus of 0.76 ± 0.22, 1.45 ± 0.55 and 1.05 ± 0.17 MPa, respectively. The films managed to produce a 1.8 °C increase in temperature, while the hydrogels reached 2.1 °C under the application of an external alternating magnetic field. The composite materials are biocompat-ible within the tested composition, demonstrating the promising application of these materials in physi-ological conditions