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Recent studies on magnetic nanoparticles (MNPs) used for Magnetic Fluid Hyperthermia treatments have shown that Brownian rotation is suppressed when they are confined within a cell. To investigate this effect we conducted a systematic study of the Specific Absorption Rate (SAR) of colloidal suspensions of MNPs in water and gels at different agarose concentration. SAR measurements were conducted by varying the frequency (f = 110–990 kHz) and amplitude (up to 17 kA/m) of the applied alternating magnetic field (AMF). MNP samples with different diameter (d = 10, 14, and 18 nm) were used. Our results show that Neel relaxation dominates SAR with negligible contribution from Brownian motion for smaller MNPs (d = 10 nm). For the largest MNPs (d = 18 nm) we observed a more significant SAR decrease in gel suspensions as compared to those in solution. In particular, when applying AMFs as the ones used in a clinical setting (16.2 kA/m at f = 110 kHz), we measured SAR value of 67 W/g in solution and 25 W/g in gel. This experimental finding demonstrates that investigation of MNPs properties should be conducted in media with viscosity similar to the one found in mammalian tissues.

The development of reproducible protocols to synthesize hard/soft nano-heterostructures (NHSs) with tailored magnetic properties is a crucial step to define their potential application in a variety of technological areas. Thermal decomposition has proved to be an effective tool to prepare such systems, but it has been scarcely used so far for the synthesis of Co-based metal/ferrite NHSs, despite their intriguing physical properties. We found a new approach to prepare this kind of nanomaterial based on a simple one-pot thermal decomposition reaction of metal-oleate precursors in the high boiling solvent docosane. The obtained NHSs are characterized by the coexistence of Co metal and Co doped magnetite and are highly stable in an air atmosphere, thanks to the passivation of the metal with a very thin oxide layer. The investigation of the influence of the metal precursor composition (a mixed iron–cobalt oleate), of the ligands (oleic acid and sodium oleate) and of the reaction time on the chemical and structural characteristics of the final product, allowed us to rationalize the reaction pathway and to determine the role of each parameter. In particular, the use of sodium oleate is crucial to obtain a metal phase in the NHSs. In such a way, the one-pot approach proposed here allows the fine control of the synthesis, leading to the formation of stable, high performant, metal/ferrite NHSs with tailored magnetic properties. For instance, the room temperature maximum energy product was increased up to 19 kJ m−3 by tuning the Co content in the metal precursor., This work was supported by EU-H2020 AMPHIBIAN Project (no. 720853) and by European Union's Horizon 2020 research and innovation programme under grant agreement no. 823717-ESTEEM3.

The present article describes the verbal and non-verbal analysis of four situations of interaction among four italian-speaking children who have linguistic difficulties. The analysis criteria, which have been used, are three: the pertinency of the verbal and non-verbal turns, the themes and the gesture. The analysis focuses on the interactive ability shown by these children and their capacity to vary them according to the interactive situation.

Nanocomposites based on an organic polymer and inorganic nanocrystals (NCs) represent a class of high impact functional materials able to convey the unique size and shape dependent properties of nano-objects to highly processable resists.[1] In this work, a novel magnetic nanocomposite based on a negative tone epoxy photoresist and magnetic colloidal Fe2O3 NCs has been manufactured for fabricating AFM probes. Epoxy-type photoresist grant superior lithographic performances when patterned by standard near- ultraviolet (UV) optical lithography, providing structures with high aspect-ratio and nearly vertical sidewalls. Such resists are at present employed in optical and micromechanical applications for the fabrication of optical waveguides, microfluidic systems and scanning probes.[2] However, these materials lack of any inherent functionality, e.g. electrical conductivity, luminescence, magnetism, piezoresistivity and dielectricity. Hence, the incorporation of NCs can confer them new properties maintaining the patterning resolutions required for the manufacturing of highly miniaturized devices. These added properties can be interesting for the fabrication of novel micro/nanoelectromechanical systems (MEMS/NEMS). The current challenge consists on incorporating NCs in the photoresist host matrix to add functionality preserving at the same time the polymer photostructurability. The NC addition has relied on the efficient dispersion of pre-synthesized functional nanosized fillers into the pre-made epoxy photoresist, by using a common solvent as recently reported by the authors in the incorporation of highly luminescent CdSe@ZnS NCs in the same epoxy photoresist.[3] Here, the magnetic properties, UV-photostructurability and mechanical characteristics of the nanocomposite have been investigated. The results show that, after the incorporation, the Fe2O3 NCs preserve their magnetism which is conveyed to the photoresist and retained after the UV-lithography process (Figure 1).

We report on the synthesis, characterization and application of a novel nanocomposite made of a negative tone epoxy based photoresist modified with organic-capped Fe(2)O(3) nanocrystals (NCs). The mechanical properties of the nanocomposite drastically improve upon incorporation of a suitable concentration of NCs in the polymer, without deteriorating its photolithography performance. High aspect ratio 3D microstructures made of the nanocomposite have been fabricated with a uniform surface morphology and with a resolution down to few micrometres. The embedded organic-capped Fe(2)O(3) NCs drastically increase the stiffness and hardness of the epoxy based photoresist matrix, making the final material extremely interesting for manufacturing miniaturized polymer based mechanical devices and systems. In particular, the nanocomposite has been used as structural material for fabricating photoplastic Atomic Force Microscopy (AFM) probes with integrated tips showing outstanding mechanical response and high resolution imaging performance. The fabricated probes consist of straight cantilevers with low stress-gradient and high quality factors, incorporating sharp polymeric tips. They present considerably improved performance compared to pure epoxy based photoresist AFM probes, and to commercial silicon AFM probes.

Colloidal magneto-plasmonic nanostructures are multifunctional materials with huge potential for applications in magnetism, optoelectronics, biomedicine and catalysis. Currently it is considered that their optical and magnetic properties are a combination of the modified properties associated with the material constituents. Herein we have investigated the morphological, magnetic and plasmonic properties of Au@magnetite core@shell heterostructured nanocrystals (HNCs) with eccentric topology. We shed light on their behavior as heat mediators for magnetic fluid hyperthermia, a promising approach to cancer therapy. A red-shift and damping of the plasmon resonance was observed, which correlated with the optical contribution and the dielectric screening of the asymmetrically distributed iron oxide shell. The magnetic properties of the Au@magnetite HNCs were investigated by comparison with those of the corresponding carved magnetite nanocrystals (NCs), obtained by selective etching of the Au domain with iodine. The iron oxide NCs featured higher magnetization and coercive field than their parent HNCs, which showed a superparamagnetic behavior instead. In addition, the carved NCs exhibited better hyperthermia performances than the HNCs, being the Specific Absorption Rate (SAR) of heat one order of magnitude higher. On the basis of the peculiar magnetic properties of the HNCs, we hypothesized that a minority wu¨stite phase was stabilized at the Au/iron-oxide interface, which could be eliminated upon oxidation to magnetite during the Au etching process. Our study opens a new scenario in the understanding of the physico-chemical behavior of this class of magneto-plasmonic heterostructures, whereby the asymmetric spatial distribution of the component materials, their complex multiphase composition and heterointerface structure determine their ultimate plasmonic, magnetic and hyperthermia properties.