Anisotropic Magnetic Heating for Adaptive Thermal Ablation.

Abstract

Thermal ablation provides minimally invasive treatment for cardiovascular and cerebrovascular conditions but risks damaging healthy tissues due to their low imaging contrast against diseased areas. This study introduces an adaptive thermal ablation probe leveraging anisotropic magnetic heating of magnetite nanorods pre-aligned within a polymer substrate. During magnetic pre-alignment, the nanorods form chain-like aggregates, enhancing their magnetic anisotropy and minimizing demagnetization effects. Under an alternating magnetic field, these features create a distinct difference in heat generation along the aggregates' easy and hard axes. This probe utilizes a bimorph structure incorporating a heating layer with aligned nanorods and an actuation layer containing NdFeB microparticles. Exposure to static and alternating magnetic fields induces probe bending, adjusting nanorod orientation to modulate heat generation and prevent overheating. In vitro experiments demonstrate successful thrombus phantom ablation in both fluid flow and porcine artery models while preserving tissue viability. This innovative approach advances thermal ablation technology by offering a safer, more precise, and adaptive solution with a high potential for clinical translation.