Parametric study of acoustically-driven microbubble cavitations in a sonochemical reactor

Exploring viscosity influence mechanisms on coating removal: Insights from single cavitation bubble behaviours in low-frequency ultrasonic settings

The role of acoustic cavitation in various surface cleaning disciplines is important. However, the physical mechanisms underlying acoustic cavitation-induced surface cleansing are poorly understood. This is due to the combination of microscopic and ultrashort timescales associated with the dynamics of acoustic cavitation bubbles. Here, we have precisely controlled single-bubble cavitation in both space and time. Ultrasonic excitation leads to the cavitation of generated single bubbles. A synchronous ultrafast photomicrographic system simultaneously records the dynamics of single acoustic cavitation bubbles (SACBs) and the cleaning process of the nearby surface in liquids with varying viscosities. Finally, we analysed the correlation between bubble dynamics and surface cleaning situations. The differences in the typical dynamic characteristics of the bubbles during collapse in liquids with varying viscosities reveal two main mechanisms underlying surface cleaning by acoustic cavitation, which are respective the Laplace pressure during the bubble's movement and liquid jets during bubble collapse. Our study provides a better physical understanding of the ultrasonic cleaning process based on acoustic cavitation, and will help to optimize and facilitate the applications of surface cleaning, especially for the cleaning of substrates with tightly attached dirt.

Fabrication of silver nanoparticles-deposited fabrics as a potential candidate for the development of reusable facemasks and evaluation of their performance

Recently, wearing facemasks in public has been raised due to the coronavirus disease 2019 epidemic worldwide. However, the performance and effectiveness of many existing products have raised significant concerns among people and professionals. Therefore, greater attempts have been focused recently to increase the efficacy of these products scientifically and industrially. In this respect, doping or impregnating facemask fabrics with metallic substances or nanoparticles like silver nanoparticles has been proposed. So, in the present study, we aimed to sonochemically coat silver nanoparticles on the non-woven Spunbond substrates at different sonication times and concentrations to develop antibacterial and antiviral facemask. The coated substrates were characterized using Field Emission Scanning Electron Microscope, Energy Dispersive X-Ray, X-ray diffraction, and Thermogravimetry analysis. The amount of silver released from the coated substrates was measured by atomic absorption spectroscopy. The filtration efficiency, pressure drop, and electrical conductivity of the coated samples were also investigated. The antibacterial activity of fabrics was evaluated against Escherichia coli and Staphylococcus aureus. Cellular viability of samples assessed by MTT and brine shrimp lethality tests. The results revealed that the higher sonication times and precursor concentrations result in a higher and more stable coating, larger particle size, wider particle size distribution, and lower content of released silver. Coated fabrics also revealed enhanced filtration efficiency (against nanosize particles), desired pressure drop, and antibacterial activity without significant cytotoxicity toward HEK 293 cells and Artemia nauplii. As a result, the coated fabrics could find potential applications in the development of facemasks for protection against different pathogenic entities.

Human clinical trial using diagnostic ultrasound and microbubbles to enhance neoadjuvant chemotherapy in HER2- negative breast cancer

Background

In vivo and in vitro experiments have demonstrated that diagnostic ultrasound combined with microbubbles (USMB) can enhance tumor chemotherapy, but few clinical studies have explored the effect of USMB in human HER2-negative breast cancer. We aimed to compare USMB combined with neoadjuvant chemotherapy (NAC) with NAC alone in the treatment of human HER2-negative breast cancer.

Methods

Patients (n=10) enrolled in the study were treated with TAC (taxane – (docetaxel), anthracycline – (epirubicin or doxorubicin liposomes), and cyclophosphamide) and ultrasound using a commercial clinical ultrasound scanner for 20 min after each chemotherapy session, followed by intermittent injections of SonoVue^® to induce sonoporation and enhance therapeutic efficacy. Contrast-enhanced ultrasound (CEUS) was used to record tumor perfusion before and after ultrasound treatment.

Results

After completion of chemotherapy, the maximum tumor diameter of patients in the combined treatment group (n=10) was significantly smaller than that in the control group (n=16) (p=0.017). Although the combined treatment group had higher overall response and clinical benefit rates than those in the control group, there was no statistically significant difference in RECIST between the combined treatment group and the control groups (p=0.590). More patients in the combination therapy group achieved pathologic complete response than in the control group (p=0.014). For combined treatment, CEUS revealed that the peak intensity, mean transit time, and area under the curve were higher after treatment than before treatment (p<0.001, p<0.001, p=0.003, respectively). Combined therapy did not cause additional toxicity or increase side effects.

Conclusion

USMB and chemotherapy can be combined in a clinical setting using commercially available equipment, without additional toxicity, and may improve the efficacy of NAC in HER2-negative breast cancer.

Curcumin-gold-polyethylene glycol nanoparticles as a nanosensitizer for photothermal and sonodynamic therapies: In vitro and animal model studies

Photothermal and ultrasound therapies are novel non-invasive strategies for tumor treatment which are equipped with a photosensitizer and sonosensitizer subsequent activation by laser irradiation and ultrasound exposure. In this study, curcumin-gold-polyethylene glycol nanoparticles (Cur-Au NPs-PEG) were synthesized, and the dual role in photothermal (PTT) and sonodynamic (SDT) therapies of melanoma cancer was evaluated. The toxicity effect of Cur-Au NPs-PEG against a mouse malignant melanoma cell line C540 (B16/F10) was firstly inspected in vitro. Cur-Au NPs-PEG provided a hyperthermal microenvironment and generated reactive oxygen species upon PTT and STD, respectively, with representing synergism effects. Studies in vivo in a tumor-bearing animal also demonstrate the superiority of PTT and SDT in destroying melanoma tumor.

Damage characteristics and surface description of near-wall materials subjected to ultrasonic cavitation

For the analysis of ultrasonic cavitation erosion on the surface of materials, the ultrasonic cavitation erosion experiments for AlCu4Mg1 and Ti6Al4V were carried out, and the changes of surface topography, surface roughness, and Vickers hardness were explored. Cavitation pits gradually expand and deepen with the increase of experiment time, and Ti6Al4V is more difficult to erode by cavitation than AlCu4Mg1. After experiments, the cavitation damage characteristics such as the single pit, the rainbow ring area, the fisheye pit, and some small pits were observed, which can be considered to be induced by a single micro-jet impact, ablation effect caused by the high temperature, micro-jet impingement with a sharp angle, and multibeam micro-jets coupling impact or negative pressure in the local area produced by micro-jet impact, respectively. The surface roughness and Vickers hardness of the material increase slowly after rapid growth at different points in time as the experiment time increases. With the increase of the ultrasonic amplitude, both of them first increase and then decrease after the ultrasonic amplitude is greater than 10.8 μm. The increases in surface roughness and Vickers hardness tend to decrease as the viscosity coefficient increases. Ultrasonic cavitation can cause submicron surface roughness and increase surface hardness by 20.36%, so it can be used as a surface treatment method.

In situconversion of rose bengal microbubbles into nanoparticles for ultrasound imaging guided sonodynamic therapy with enhanced antitumor efficacy

Sonosensitizer microbubbles enhance drug accumulation and the antitumor efficacy of sonodynamic therapy by ultrasound mediated micro to nano conversion.

Tumor targeting DVDMS-nanoliposomes for an enhanced sonodynamic therapy of gliomas

UTMD-assisted intelligent DVDMS encapsulate iRGD-Liposomes mediate SDT with deep tumor penetration and specific targeting ability enhanced anti-glioma efficacy.

Activation of microbubbles by low-intensity pulsed ultrasound enhances the cytotoxicity of curcumin involving apoptosis induction and cell motility inhibition in human breast cancer MDA-MB-231 cells

Ultrasound and microbubbles-mediated drug delivery has become a promising strategy to promote drug delivery and its therapeutic efficacy. The aim of this research was to assess the effects of microbubbles (MBs)-combined low-intensity pulsed ultrasound (LPUS) on the delivery and cytotoxicity of curcumin (Cur) to human breast cancer MDA-MB-231 cells. Under the experimental condition, MBs raised the level of acoustic cavitation and enhanced plasma membrane permeability; and cellular uptake of Cur was notably improved by LPUS-MBs treatment, aggravating Cur-induced MDA-MB-231 cells death. The combined treatment markedly caused more obvious changes of cell morphology, F-actin cytoskeleton damage and cell migration inhibition. Our results demonstrated that combination of MBs and LPUS may be an efficient strategy for improving anti-tumor effect of Cur, suggesting a potential effective method for antineoplastic therapy.

Numerical simulation of the nonlinear ultrasonic pressure wave propagation in a cavitating bubbly liquid inside a sonochemical reactor

We investigate the acoustic wave propagation in bubbly liquid inside a pilot sonochemical reactor which aims to produce antibacterial medical textile fabrics by coating the textile with ZnO or CuO nanoparticles. Computational models on acoustic propagation are developed in order to aid the design procedures. The acoustic pressure wave propagation in the sonoreactor is simulated by solving the Helmholtz equation using a meshless numerical method. The paper implements both the state-of-the-art linear model and a nonlinear wave propagation model recently introduced by Louisnard (2012), and presents a novel iterative solution procedure for the nonlinear propagation model which can be implemented using any numerical method and/or programming tool. Comparative results regarding both the linear and the nonlinear wave propagation are shown. Effects of bubble size distribution and bubble volume fraction on the acoustic wave propagation are discussed in detail. The simulations demonstrate that the nonlinear model successfully captures the realistic spatial distribution of the cavitation zones and the associated acoustic pressure amplitudes.