Praseodymium-Doped Cobalt Ferrite Nanoparticles: Novel Selective Anticancer Agents with Magnetic Modulation ^†

In the pursuit of multifunctional nanomaterials for oncological applications, cobalt ferrite nanoparticles doped with praseodymium (CoFe_2−yPryO₄, y = 0–0.2) were synthesized using a scalable sol–gel auto-combustion route and structurally tailored through controlled doping. These nanomaterials, further stabilized with (2-hydroxypropyl)-γ-cyclodextrin, demonstrated highly tunable magnetic, morphological, and biological behaviors [1]. X-ray diffraction and fourier transform infrared spectroscopy (FTIR) confirmed the phase purity and successful lattice incorporation of Pr³⁺ at low doping levels, while higher substitutions led to the emergence of a secondary PrFeO₃ phase. The dopant induced a consistent increase in lattice parameters and particle sizes, as seen in transmission electron microscopy (TEM), and influenced magnetic saturation and remanence, which declined with increased Pr content and cyclodextrin coating. Biologically, the nanoparticles exhibited minimal cytotoxicity in normal HaCaT keratinocytes, even at the highest concentrations tested, while exerting potent, dose-dependent antiproliferative effects on melanoma (A375), breast (MCF-7), and colorectal (HT-29) cancer cell lines. The Pr 6-CD and Pr 7-CD formulations stood out for their exceptional selectivity and low IC₅₀ values, supporting a direct correlation between Pr content and anticancer efficacy. These findings underscore the promise of Pr-doped cobalt ferrites as selective and biocompatible theranostic agents, warranting further in-depth mechanistic and translational studies.