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

ZIF-8-based nanostructures were engineered for cavitation enhancement. • Bare ZIF-8 leads to a non-monotonic size-dependent apparent cavitation threshold. • Particle morphology modulates cavitation in addition to material type. • Mesoporous silica shells amplify low-threshold cavitation for all sizes. • Interfacial engineering enables MOF-based low cavitation threshold. 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. Download: Download high-res image (94KB) Download: Download full-size image