Magnetically Guided Theranostics: Novel Nanotubular Magnetic Resonance Imaging Contrast System Using Halloysite Nanotubes Embedded with Iron–Platinum Nanoparticles for Hepatocellular Carcinoma Treatment

Halloysite nanotubes (HNTs) have a layered structure of clay silicate minerals and a tubular shape, which is suitable for the uniform loading of small substrates and drug molecules. The inner diameter of HNTs with an acidic solvent is selectively etched to increase the loading capacity of magnetic iron–platinum (FePt) nanoparticles. The FePt nanoparticles and etched HNTs (eHNT) are then composited by vacuum decompression. The resulting product is named FePt@eHNT and is used as a contrast agent for T2-weighted magnetic resonance imaging. According to a comprehensive analysis of the material and its magnetic properties, by adding different proportions of HNTs before and after modification, the saturation magnetization can reach 23.769 emu g⁻¹, which is higher than that of the composite materials studied in previous studies. This is because the tubular structure promotes the orderly displacement of the FePt nanoparticles under three-dimensional space constraints and the uniform effect of the magnetic field. In addition, the magnetothermal effect of the composite material is observed and its potential as an imaging agent is investigated. In this study, the enhancement of its ferromagnetism and its potential to become a multifunctional composite material for applications in drug delivery, magnetic hyperthermia, and bioimaging is demonstrated.