A comparative analysis of low intensity ultrasound effects on living cells: from simulation to experiments

Abstract

Ultrasounds are already broadly exploited in clinical diagnostics and are now becoming a powerful and not harmful tool in antitumoral therapies, as they are able to produce damages towards cancer cells, thank to inertial cavitation and temperature increase. The use of US alone or combined to molecular compounds, microbubbles or solid-state nanoparticles is the focus of current research and clinical trials, like thermoablation, drug sonoporation or sonodynamic therapies. In the present work, we discuss on the non-thermal effects of ultrasound and the conditions which enable oxygen radical production and which role they can have in provoking the death of different cancer cell lines. In this perspective, we set a mathematical model to predict the pressure spatial distribution in a defined water sample volume and thus obtain a map of acoustic pressures and acoustic intensities of the applied ultrasound at different input powers. We then validate and verify these numerical results with direct acoustic measurements and by detecting the production of reactive oxygen species (ROS) by means of sonochemiluminescence (SCL) and electron paramagnetic resonance (EPR) spectroscopy, applied to the same water sample volume and using the same US input parameters adopted in the simulation. Finally, the various US conditions are applied to two different set of cancer cell lines, a cervical adenocarcinoma and a hematological cancer, Burkitt’s lymphoma. We hypothesize how the ROS generation can influence the recorded cell death. In a second set of experiments, the role of semiconductor metal oxide nanocrystals, i.e. zinc oxide, is also evaluated by adding them to the water and biological systems. In particular, the role of ZnO in enhancing the ROS production is verified. Furthermore, the interplay among US and ZnO nanocrystals is evaluated in provoking cancer cell death at specific conditions. This study demonstrates a useful correlation between numerical simulation and experimental acoustic validation as well as with ROS measurement at both qualitative and quantitative levels during US irradiation of simple water solution. It further tries to translate the obtained results to justify one of the possible mechanisms responsible of cancer cell death. It thus aims to pave the way for the use of US in cancer therapy and a better understanding on the non-thermal effect that a specific set of US parameters can have on cancer cells cultured in vitro. Graphical abstract

Mapping knowledge landscapes and emerging trends of sonodynamic therapy: A bibliometric and visualized study

“…With remarkable advancements in nanotechnology, nanomaterials have been introduced as an alternative route to overcome the above issues of traditional sonosensitizers and increasing number of nano-sonosensitizers have been designed and widely used recently ( Guo et al, 2022 ). As for ultrasound, studies mainly concentrated on ultrasound setting parameters including frequency, intensity, transducer geometry, coupling media, as well as other experimental conditions that could affect reproducibility and transferability ( Secomski et al, 2017 ; Araújo Martins et al, 2021 ; Tamboia et al, 2022 ). However, to our knowledge, the ultrasound parameters in different laboratories are still not fully standardized.…”

Anti-CD38 targeted nanotrojan horses stimulated by acoustic waves as therapeutic nanotools selectively against Burkitt’s lymphoma cells

“…It has been reported in the previous literature [ 11 , 12 , 18 ], the enhanced ROS production generated by the ultrasound irradiation of ZnO nanoparticles, due to the increased number of inertial cavitation nuclei at NPs surface. ROS are involved in various cell signaling processes [ 61 ], and an imbalance in cellular redox homeostasis could cause cellular component damages, as well as the activation of many signal pathways liable of cell death, causing ROS-mediated apoptosis or necrosis [ 62 ].…”

“…Recently Zinc oxide nanocrystals (ZnO NCs) has been proposed as effective sonosensitizing nanoparticles, able to produce dramatic effect when applied in combination with ultrasound [ 11 ] or shock waves [ 13 ] to different types of cancer cells [ 14 , 15 ], yet producing ROS, zinc cation release and mechanical damages. Actually, zinc oxide nanoparticles are among the most promising materials for theranostic applications [ 14 , 16 ] due to their wide band gap [ 17 ], suitable for optical imaging, their high surface reactivity, and their response to ultrasound irradiation [ 10 , 11 , 13 , 18 ] leading to the above mentioned physico-chemical damages to cells. Furthermore, ZnO has been proven to be selectively toxic per se against cancer cells [ 16 , 19 ] and more tolerated by healthy ones.…”

Synergistic Piezo-Catalytic Inactivation of Bacteria by Dual-Frequency Ultrasound (120 + 1700 kHz) Using Persulfate and ZnO Nano- and Microparticles

“…Recently, Li et al (2023) [29] comprehensively surveyed the mechanisms of piezoelectric effect-mediated catalysis with different piezoelectric materials and their applications in environmental pollution remediation, including water disinfection. •OH was found to be the main oxidation species under exposure to 38 and 80 kHz in the presence of ZnO [30], whereas •O 2 − and •OH were primarily generated by the 1 MHz + ZnO process [31]. ZnO-based composites, such as Bi 2 O 3 -ZnO-B 2 O 3 [32,33], are also fabricated and used for piezo-catalysis.…”