Interfacial regulation of low-intensity acoustic cavitation by MOF-based nanoparticles

Ultrasound-induced cavitation plays an important role in ultrasound-mediated treatments, drug delivery, and sonodynamic therapy, yet the mechanism of regulatory functions of metal-organic framework (MOF) nanoparticles toward cavitation intensity is still not fully understood. In this study, zeolitic imidazolate framework-8 (ZIF-8) was used as a model system to investigate the effects of particle size, external morphology, and mesoporous silica shell engineering on cavitation behavior under low-intensity ultrasound. The results showed that bare ZIF-8 nanoparticles exhibited limited cavitation enhancement, but displayed a clear non-monotonic size dependence, with the intermediate-sized sample showing the lowest apparent cavitation threshold. Comparison between rhombic dodecahedral and cubic ZIF-8 further indicated that the external geometric boundary of the particles affects their nonlinear acoustic response. Compared with size and morphology regulation alone, mesoporous silica coating markedly enhanced the third-harmonic response of ZIF-8-based particles and reduced the cavitation threshold across the investigated size range, particularly in the low-intensity region. These findings support an interface-governed mechanism in which particle geometry and mesoporous shell structure modulate gas-nucleus stabilization and activation, providing a strategy for constructing MOF-based low-threshold cavitation nanoplatforms.