The incorporation of magnetic nanoparticles into poly(N-isopropylacrylamide) (PNIPAAm) and chitosan microgels gives rise to hybrid systems that combine the microgels swelling capacity with the interesting features presented in magnetic nanoparticles. The presence of chitosan that act as surfactant for magnetic nanoparticles provides a simplistic approach which allows the encapsulation of magnetic nanoparticles without any previous surface modification. Spherical and highly monodisperse microgels with diameters in the range of 200 to 500 nm were obtained. The encapsulation of magnetic nanoparticles in the polymer matrix was confirmed by high resolution Scanning Electron Microscopy in transmission mode. Volume phase transition of the microgels was accessed by Dynamic Light Scattering measurements. It was observed that the thermosensitivity of the PNIPAM microgels still persists in the hybrid microgels; however, the swelling ability is compromised in the microgels with highest chitosan content. The heating performance of the hybrid magnetic microgels, when submitted to an alternating magnetic field, was also evaluated demonstrating the potential of these systems for hyperthermia treatments.

Iron oxide nanoparticles (NPs) have been extensively studied in the last few decades for several biomedical applications such as magnetic resonance imaging, magnetic drug delivery and hyperthermia. Hyperthermia is a technique used for cancer treatment which consists in inducing a temperature of about 41–45 °C in cancerous cells through magnetic NPs and an external magnetic field. Chemical precipitation was used to produce iron oxide NPs 9 nm in size coated with oleic acid and trisodium citrate. The influence of both stabilizers on the heating ability and in vitro cytotoxicity of the produced iron oxide NPs was assessed. Physicochemical characterization of the samples confirmed that the used surfactants do not change the particles' average size and that the presence of the surfactants has a strong effect on both the magnetic properties and the heating ability. The heating ability of Fe3O4 NPs shows a proportional increase with the increase of iron concentration, although when coated with trisodium citrate or oleic acid the heating ability decreases. Cytotoxicity assays demonstrated that both pristine and trisodium citrate Fe3O4 samples do not reduce cell viability. However, oleic acid Fe3O4 strongly reduces cell viability, more drastically in the SaOs-2 cell line. The produced iron oxide NPs are suitable for cancer hyperthermia treatment and the use of a surfactant brings great advantages concerning the dispersion of NPs, also allowing better control of the hyperthermia temperature.

Cancer is one of the main causes of death in the world and its incidence increases every
day. Current treatments are insufficient and present many breaches. Hyperthermia is an old
concept and was early established as a cancer treatment option, mainly in superficial
cancers. More recently, the concept of intracellular hyperthermia emerged wherein magnetic
particles are concentrated at the tumor site and remotely heated using an applied magnetic
field to achieve hyperthermic temperatures (42-45ºC). Many patents have been registered in
this area since the year 2000. This chapter presents the most relevant information organized
in two main categories according to the use or not of nanotechnology.

Iron oxide nanoparticles are having been extensively investigated for several biomedical applications such as hyperthermia and magnetic resonance imaging. However, one of the biggest problems of these nanoparticles is their aggregation.

Taking this into account, in this study the influence of three different surfactants (oleic acid, sodium citrate and Triton X-100) each one with various concentrations in the colloidal solutions stability was analyzed by using a rapid and facile method, the variation in the optical absorbance along time.

The synthesized nanoparticles through chemical precipitation showed an average size of 9 nm and a narrow size distribution. X-ray diffraction pattern and Fourier Transform Infrared analysis confirmed the presence of pure magnetite. SQUID measurements showed superparamagnetic properties with a blocking temperature around 155 K. In addition it was observed that neither sodium citrate nor Triton X-100 influences the magnetic properties of the nanoparticles. On the other hand, oleic acid in a concentration of 64 mM decreases the saturation magnetization from 67 to 45 emu/g. Oleic acid exhibits a good performance as stabilizer of the iron oxide nanoparticles in an aqueous solution for 24 h, for concentrations that lead to the formation of the double layer.

Improved thermoelectric properties of Aluminum Zinc Oxide (AZO) thin films deposited by radio frequency (RF) and pulsed Direct Current (DC) magnetron sputtering at room temperature are reported. In both techniques films were deposited using sintered and non-sintered targets produced from nano-powders. It is confirmed that both the Al doping concentration and film thickness control the thermoelectric, optical and structural properties of these films. Seebeck coefficients up to −134 μV K−1 and electrical conductivities up to 4 × 104 (Ω m)−1 lead to power factors up to 4 × 10−4 W mK−2, which is above the state-of-the-art for similar materials, almost by a factor of three. The thermoelectric I–V response of an optimized AZO element with a planar geometry was measured and a maximum power output of 2.3 nW, for a temperature gradient of 20 K near room temperature, was obtained. Moreover, the low thermal conductivity (<1.19 W mK−1) yields a ZT value above 0.1. This is an important result as it is at least three times higher than the ZT found in the literature for AZO, at room temperature, opening new doors for applications of this inexpensive, abundant and environmental friendly material, in a new era of thermoelectric devices.