Macroscopic Phase-Change Drug Carrier Ball with Photothermally Controlled Release and Magnetically Controlled Transport Properties

Phase-change materials (PCMs) are widely regarded as effective thermo-responsive gating materials for on-demand drug release. Most previous studies utilizing PCMs for this purpose focus on small colloidal micro- and nanoparticles. In this study, macroscopic phase-change drug carriers are demonstrated in the form of millimeter-sized balls, which offer enhanced visibility. These wax-based phase-change macroballs, composed of paraffin, fatty alcohols, or fatty acids, can be easily fabricated with customizable volumes by depositing melted wax droplets containing functional components–such as drugs, photothermal agents, surfactants, and magnetites–onto omniphobic surfaces, where they spontaneously dewet and solidify upon natural cooling. These macroballs can be rapidly heated and melted upon near-infrared irradiation due to the incorporation of low-melting-point liquid metal (LM) eutectic Ga–In microdroplets as photothermal agents, enabling efficient on-demand drug release. Furthermore, by adsorbing magnetically susceptible Fe₃O₄ nanoparticles onto the LM microdroplets, the transport of the macroballs becomes magnetically controllable, as demonstrated by the use of a permanent magnet or electromagnet. The strategies demonstrated in this study provide a simple and scalable approach to fabricating high-visibility, trackable macroscopic phase-change balls with on-demand photothermal drug release and magnetically controlled transport properties.