Precision‐Engineered Cobalt‐Doped Iron Oxide Nanoparticles: From Octahedron Seeds to Cubical Bipyramids for Enhanced Magnetic Hyperthermia

Abstract Despite notable advancements, the significantly improved yet suboptimal heating efficiency of current magnetic nanoparticles hinders the effectiveness of systemically delivered magnetic hyperthermia in reducing tumor size or halting growth. Addressing this challenge, the seed‐and‐growth thermal decomposition method has been developed to synthesize cobalt‐doped iron oxide nanoparticles (Co‐IONPs) featuring a cubical bipyramid morphology, consisting of both magnetite and maghemite phases within their nanostructure. They possess an exceptional specific absorption rate (SAR) of 14 686 ± 396 W g⁻¹ Fe, inducing a temperature rise of 3.73 °C s ⁻¹ when subjected to an alternating magnetic field (AMF, 315 kHz; 26.8 kA m ⁻¹ ). The cubical bipyramid‐shaped Co‐IONPs, functionalized with LHRH peptide, efficiently accumulate in ovarian cancer xenografts following an intravenous injection at a relatively low dose of 4 mg kg ⁻¹ , elevating intratumoral temperatures beyond 50 °C with a high heating rate. In contrast to previously reported magnetic nanoparticles with ultrahigh heating efficiency, the developed cubical bipyramid‐shaped nanoparticles effectively halt ovarian cancer tumor growth after a single 30‐min session of magnetic hyperthermia. These outcomes underscore the potential of shape‐dependent magnetic hyperthermia, where the cubical bipyramid morphology significantly enhances the heating efficiency and therapeutic efficacy of magnetic nanoparticles, improving the effectiveness of hyperthermia‐based cancer treatments.