Superparamagnetic iron oxide nanoparticles doped with zinc and modified with a cationic derivative of chitosan (SPION-Zn-CCh(+)) that exhibited enhanced activity in magnetic hyperthermia were synthesized and characterized structurally, magnetically, and biologically. The optimum zinc content and the polymer coating were found to be important to maximize the hyperthermic effect in the obtained nanoferrites, which effectively worked at concentrations as low as 0.55 mg Fe per mL. The average core diameter was found to be ca. 10 nm as revealed by SAXS and TEM measurements, while the formed small aggregates of the polymer coated nanoparticles reached a size of ca. 200 nm. The nanoferrite structure was further obtained using Mössbauer spectroscopy and XANES revealing the maximum Zn doping. The much higher (ca. 60%) intrinsic loss power determined for SPION-Zn-CCh(+) as compared to the native iron oxide nanoparticles, together with the long term (12 months) stability of their dispersion and biocompatibility, makes these nanoferrites very promising materials for magnetic hyperthermia therapy. The proposed synthetic method employing a cationic polysaccharide opens up also new opportunities for the formation of other metal ferrites with composition and structure previously unobtainable and potentially superior e.g. magnetic properties.

A controlled cell detachment and transfer into a new place was triggered only by an external magnetic field.

Here we present a facile and efficient method of controlled embedding of inorganic nanoparticles into an ultra-thin (<15 nm) and flat (~1.0 nm) polymeric coating that prevents unwanted aggregation. Hybrid polymer brushes-based films were obtained by simultaneous incorporation of superparamagnetic iron oxide nanoparticles (SPIONs) with diameters of 8–10 nm into a polycationic macromolecular matrix during the surface initiated atom transfer radical polymerization (SI-ATRP) reaction in an ultrasonic reactor. The proposed structures characterized with homogeneous distribution of separated nanoparticles that maintain nanometric thickness and strong magnetic properties are a good alternative for commonly used layers of crosslinked nanoparticles aggregates or bulk structures. Obtained coatings were characterized using atomic force microscopy (AFM) working in the magnetic mode, secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS).

A broad spectrum of applications of magnetic nanoparticles leads to the need for the precise tuning of their magnetic properties. In this study, a series of magnetite and zinc-ferrite nanoparticles were successfully prepared by modified high-temperature synthesis in a controlled gas atmosphere. Nanoparticles with different zinc to iron ratios and pure Fe₃O₄ were obtained. The structure of the nanoparticles was studied by transmission electron microscopy and Mössbauer spectroscopy. These revealed the single domain character of the nanoparticles and the influence of the synthesis temperature and zinc to iron ratio on their shape and size. Chemical structure was characterized by inductively coupled plasma optical emission spectroscopy, energy dispersive X-ray spectroscopy and thermogravimetric analysis. X-ray photoelectron spectroscopy coupled with an argon gas cluster ion beam (Ar-GCIB) allowed the study of subsequent layers of the nanoparticles without altering their chemical structure. This revealed the presence of a carbon layer on all nanoparticles consisting of capping agents used in the synthesis and revealed the core–shell character of the zinc ferrite particles. In addition, different types of zinc infusions in the nanoparticle structure were observed when using different Zn/Fe ratios. Finally, magnetic studies performed by means of vibrating sample magnetometry proved the superparamagnetic behavior of all the samples.