Newly Synthesized CoFe2-xPrxO4 (x = 0; 0.01; 0.03; 0.05; 0.1; 0.15; 0.2) Nanoparticles Reveal Promising Selective Anticancer Activity against Melanoma (A375), Breast Cancer (MCF-7) and Colon Cancer (HT-29) Cells

In this study, praseodymium-doped cobalt ferrite nanoparticles (CoFe₂₋yPryO₄, y = 0–0.2) were synthesized via sol-gel auto-combustion and systematically characterized to assess their structural, morphological, magnetic, and biological properties. X-ray diffraction (XRD) confirmed single-phase cubic cobalt ferrite formation for samples with y ≤ 0.05 and the emergence of a secondary orthorhombic PrFeO₃ phase at higher dopant concentrations. FTIR spectroscopy identified characteristic metal–oxygen vibrations and revealed a progressive shift of absorption bands with increasing Pr content. Vibrating sample magnetometry (VSM) demonstrated a gradual decline in saturation (Ms) and remanent (Mr) magnetization with praseodymium doping, an effect further intensified by cyclodextrin surface coating. TEM analyses revealed a particle size increase correlated with dopant level, while SEM images displayed a porous morphology typical of combustion-synthesized ferrites. In vitro cell viability assays showed minimal toxicity in normal human keratinocytes (HaCaT), while significant antiproliferative activity was observed against human cancer cell lines A375 (melanoma), MCF-7 (breast adenocarcinoma), and HT-29 (colorectal adenocarcinoma), particularly in Pr 6-CD and Pr 7-CD samples. These findings suggest that praseodymium substitution and cyclodextrin coating can effectively modulate the physicochemical and anticancer properties of cobalt ferrite nanoparticles, making them promising candidates for future biomedical applications.