TX-100 capped iron oxide nanoparticle transformation and implications for induction heating and hyperthermia treatment

The use of superparamagnetic iron oxide nanoparticles (SPIONs) has gained increasing attention in the scientific community with experimental success recorded in medical science through magnetic hyperthermia in cancer treatment and targeted drug delivery. Determining how the nanoparticles and their capping agents react with their surroundings is imperative to optimizing treatments as well as researching new applications for inductively heated nanoparticles. Suspensions of iron oxide nanoparticles capped with TX-100 were prepared in both deionized (DI) water and saline solutions to create a comparison study. The samples were heated via induction, followed by TEM characterization and diffraction pattern analysis for the particles removed after exposure to the high-frequency oscillating magnetic fields. Additional characterization was performed with dynamic light scattering (DLS), magnetic force microscopy (MFM), and X-ray photoelectron spectroscopy (XPS), for determining subsequent changes in their colloidal properties, magnetic interaction, and composition. The introduction of a saline environment promoted clustering, of which its appearance was unique from the DI suspension. This clustering accompanied an increased specific absorption rate for the suspension; moreover, smaller nanoparticles were also observed around the exterior of the clusters. The change in the agglomeration of the nanoparticles within the saline suspensions, and knowledge of previous research into the behavior of TX-100 in the presence of electrolytes, suggests that the addition of sodium chloride salt brought about a chemical change within the samples. MFM measurements show that the particle clusters within the saline suspensions possess higher magnetic attractive forces, and when coupled with the calorimetric measurements gathered, it can be concluded that this positively affected the nanoparticles’ heat output. Such implications and conclusions found will prove useful in optimizing nanoparticle heating for applications such as magnetic hyperthermia.