Solvent polarity-regulated morphologies of MOFs for enhanced tumor microwave hyperthermia

Abstract

Microwave (MW) hyperthermia is a well-established tumor therapy characterized with rapid heating rate and deep tissue penetration. Metal-organic frameworks (MOFs) have emerged as promising MW sensitizers due to their diverse morphologies, which directly determine the microwave-to-thermal conversion efficiencies. Herein, a mild morphological regulation strategy for copper 1,3,5-benzenetricarboxylate (HKUST-1) via adjusting solvent polarity is reported, which enables the controllable transformation between spherical and strip-like morphologies. From the molecular simulation, it confirms that the change of solvent polarity regulates the strength and parameters of intermolecular hydrogen bonds, results in inducing the aggregation behavior of HKUST-1 nanoparticles. In vitro MW heating experiments demonstrate distinct microwave-to-thermal conversion efficiencies between two morphologies, enabling their applications in different tumor treatment scenarios. The strip-like HKUST-1 exhibits significantly enhanced MW absorption performance compared with spherical HKUST-1, which is attributed to the increased copper ion concentration and enhanced dielectric loss caused by morphological aggregation. Compared with the control group, spherical HKUST-1 increases as high as 80.4 % of the microwave-to-thermal conversion efficiency and exhibits a tumor inhibition rate of approximately 73.6 %, rendering it suitable for tumor therapies requiring mild thermal modulation to minimize damage to surrounding normal tissues. In contrast, strip-like HKUST-1 improves the conversion efficiency to 101.6% and achieves a tumor inhibition rate of approximately 82.3%, enabling rapid and effective ablation of large-volume tumors. In summary, this work provides a novel strategy for the morphological regulation of MOFs and lays a solid foundation for the development of high-performance microwave sensitizers for synergistic tumor therapy.