Fabian Starsich

An Integrated Microrobotic Platform for On‐Demand, Targeted Therapeutic Interventions

The presented microrobotic platform combines together the advantages of self-folding NIR light sensitive polymer bilayers, magnetic alginate microbeads, and a 3D manipulation system, to propose a solution for targeted, on-demand drug and cell delivery. First feasibility studies are presented together with the potential of the full design.

Gas-phase synthesis of magnetic metal/polymer nanocomposites

Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields.

Silica-Coated Nonstoichiometric Nano Zn-Ferrites for Magnetic Resonance Imaging and Hyperthermia Treatment

Large-scale and reproducible synthesis of nanomaterials is highly sought out for successful translation into clinics. Flame aerosol technology with its proven capacity to manufacture high purity materials (e.g., light guides) up to kg h-1 is explored here for the preparation of highly magnetic, nonstoichiometric Zn-ferrite (Zn0.4 Fe2.6 O4 ) nanoparticles coated in situ with a nanothin SiO2 layer. The focus is on their suitability as magnetic multifunctional theranostic agents analyzing their T2 contrast enhancing capability for magnetic resonance imaging (MRI) and their magnetic hyperthermia performance. The primary particle size is closely controlled from 5 to 35 nm evaluating its impact on magnetic properties, MRI relaxivity, and magnetic heating performance. Most importantly, the addition of Zn in the flame precursor solution facilitates the growth of spinel Zn-ferrite crystals that exhibit superior magnetic properties over iron oxides typically made in flames. These properties result in strong MRI T2 contrast agents as shown on a 4.7 T small animal MRI scanner and lead to a more efficient heating with alternating magnetic fields. Also, by injecting Zn0.4 Fe2.6 O4 nanoparticle suspensions into pork tissue, MR-images are acquired at clinically relevant concentrations. Furthermore, the nanothin SiO2 shell facilitates functionalization with polymers, which improves the biocompatibility of the theranostic system.

Coercivity Determines Magnetic Particle Heating

Diseased cell treatment by heating with magnetic nanoparticles is hindered by their required high concentrations. A clear relationship between heating efficiency and magnetic properties of nanoparticles has not been attained experimentally yet due to limited availability of magnetic nanoparticles with varying size and composition. Here, versatile flame aerosol technology is used for the synthesis of 21 types of ferro-/ferrimagnetic nanocrystals with varying composition, size, and morphology for hyperthermia and thermoablation therapy. Heating efficiency, magnetic hysteresis, and first-order reversal curves of these materials are compared. The maximum heating performance occurs near the transition from superparamagnetic to single domain state, regardless of particle composition. Most importantly, the ratio between saturation magnetization and coercivity can be linked to the heating properties of magnetic nanoparticles. Magnetic interaction is controlled by changes in the architecture of the nanoparticles and closely analyzed by first-order reversal curves. Silica-coated nonstoichiometric Gd-Zn ferrite exhibits the most promising therapeutic capability at relatively low particle concentrations, as shown in vitro with cancerous prostate cells.