Cavitation Induced by Janus-Like Mesoporous Silicon Nanoparticles Enhances Ultrasound Hyperthermia

Abstract

The presence of nanoparticles lowers the levels of ultrasound (US) intensity needed to achieve the therapeutic effect and improves the contrast between healthy and pathological tissues. Here, we evaluate the role of two main mechanisms that contribute to the US-induced heating of aqueous suspensions of biodegradable nanoparticles (NPs) of mesoporous silicon prepared by electrochemical etching of heavily boron-doped crystalline silicon wafers in a hydrofluoric acid solution. The first mechanism is associated with an increase of the attenuation of US in the presence of NPs due to additional scattering and viscous dissipation, which was numerically simulated and compared to the experimental data. The second mechanism is caused by acoustic cavitation leading to intense bubble collapse and energy release in the vicinity of NPs. This effect is found to be pronounced for as-called Janus NPs produced via a nano-stopper technique, which allow us to prepare mesoporous NPs with hydrophobic inner pore walls and hydrophilic external surface. Such Janus-like NPs trap air inside the pores when dispersed in water. The precise measurement of the heating dynamics in situ enabled us to detect the excessive heat production by Janus-like NPs over their completely hydrophilic counterparts. The excessive heat is attributed to the high intensity cavitation in the suspension of Janus-like NPs. The present work elicits the potential of specifically designed Janus-like mesoporous silicon NPs in the field of nanotheranostics based on ultrasound radiation.

Remotely Activated Nanoparticles for Anticancer Therapy

“…Furthermore, investigating the interactions between silicon NPs and US, Sviridov et al highlighted two main mechanisms. (1) an enhanced scattering and viscous dissipation of the US energy in the medium with NPs, resulting in the heating of the medium; (2) an augmented acoustic cavitation-associated heating, more pronounced in the case of NPs with hydrophobic inner walls [158].…”

Surface Wettability of Nanoparticle Modulated Sonothrombolysis

“…Sonoluminescence, one of the dominant mechanisms, refers to the ROS generation by luminous energy transfer during electronic excitation of sensitizer under US irradiation. The cavitation effect is another widely accepted SDT mechanism, which refers to the rapid expansion of the bubbles in liquid under US irradiation, followed by rapidly collapse [ 4 ] and the generation of shock waves, [ 5 ] micro‐jet, [ 6 ] high temperature, [ 7 ] and high pressure, [ 8 ] leading to decompose water into ROS, [ 9 ] which in turn promotes cellular apoptosis. Previous reports have shown that bubbles can act as nucleation sites for lowering cavitation thresholds with the assistance of nanoparticles, then enhancing the cavitation effect.…”

Recent advances in nanomaterials for sonodynamic therapy

“…In addition to TiO2, Si nanostructures also have been widely used in SDT [123,124]. For example, Osminkina et al prepared Si nanowires (Si NWs, about 5 μm in length and 200 nm in diameter) via a cheap and efficient metal-assisted etching method [125].…”