Microfluidic Detection of SPIONs and Co-Ferrite Ferrofluid Using Amorphous Wire Magneto-Impedance Sensor.

The detection of magnetic nanoparticles in a liquid medium and the quantification of their concentration have the potential to improve the efficiency of several relevant applications in different fields, including medicine, environmental remediation, and mechanical engineering. To this end, sensors based on the magneto-impedance effect have attracted much attention due to their high sensitivity to the stray magnetic field generated by magnetic nanoparticles, their simple fabrication process, and their relatively low cost. To improve the sensitivity of these sensors, a multidisciplinary approach is required to study a wide range of soft magnetic materials as sensing elements and to customize the magnetic properties of nanoparticles. The combination of magneto-impedance sensors with ad hoc microfluidic systems favors the design of integrated portable devices with high specificity towards magnetic ferrofluids, allowing the use of very small sample volumes and making measurements faster and more reliable. In this work, a magneto-impedance sensor based on an amorphous Fe73.5Nb3Cu1Si13.5B9 wire as the sensing element is integrated into a customized millifluidic chip. The sensor detects the presence of magnetic nanoparticles in the ferrofluid and distinguishes the different stray fields generated by single-domain superparamagnetic iron oxide nanoparticles or magnetically blocked Co-ferrite nanoparticles.

Dual-responsive magnetic nanodroplets for controlled oxygen release via ultrasound and magnetic stimulation.

Magnetic oxygen-loaded nanodroplets (MOLNDs) are a promising class of nanomaterials dually sensitive to ultrasound and magnetic fields, which can be employed as nanovectors for drug delivery applications, particularly in the field of hypoxic tissue treatment. Previous investigations were primarily focused on the application of these hybrid systems for hyperthermia treatment, exploiting magnetic nanoparticles for heat generation and nanodroplets as carriers and ultrasound contrast agents for treatment progress monitoring. This work places its emphasis on the prospect of obtaining an oxygen delivery system that can be activated by both ultrasound and magnetic fields. To achieve this goal, Fe3O4 nanoparticles were employed to decorate and induce the magnetic vaporization of OLNDs, allowing oxygen release. We present an optimized method for preparing MOLNDs by decorating nanodroplets made of diverse fluorocarbon cores and polymeric coatings. Furthermore, we performed a series of characterizations for better understanding how magnetic decoration can influence the physicochemical properties of OLNDs. Our comprehensive analysis demonstrates the efficacy of magnetic stimulation in promoting oxygen release compared to conventional ultrasound-based methods. We emphasize the critical role of selecting the appropriate fluorocarbon core and polymeric coating to optimize the decoration process and enhance the oxygen release performance of MOLNDs.

Improvement of Hyperthermia Properties of Iron Oxide Nanoparticles by Surface Coating.

Magnetic hyperthermia is an oncological therapy that exploits magnetic nanoparticles activated by radiofrequency magnetic fields to produce a controlled temperature increase in a diseased tissue. The specific loss power (SLP) of magnetic nanoparticles or the capability to release heat can be improved using surface treatments, which can reduce agglomeration effects, thus impacting on local magnetostatic interactions. In this work, Fe3O4 nanoparticles are synthesized via a coprecipitation reaction and fully characterized in terms of structural, morphological, dimensional, magnetic, and hyperthermia properties (under the Hergt-Dutz limit). Different types of surface coatings are tested, comparing their impact on the heating efficacy and colloidal stability, resulting that sodium citrate leads to a doubling of the SLP with a substantial improvement in dispersion and stability in solution over time; an SLP value of around 170 W/g is obtained in this case for a 100 kHz and 48 kA/m magnetic field.

Fabrication of new Magnetic Micro-Machines for minimally invasive surgery.

Magnetic Micro-Machines (MMM) have been proposed as effective tools for minimally invasive surgery. We propose an innovative and low cost MMM manufacturing process based on casting of a mixture of SmCo powders and acrylic resin into silicone moulds. After developing a MMM prototype, we tested its swimming ability by using different siliconic oils of known kinematic viscosity. The propulsion efficiency, given by the velocity and frequency ratio, has been found comparable with other MMM reported in the literature.