Investigation of Microbubble Cavitation-Induced Calcein Release from Cells In Vitro

Effect of ultrasound application on the growth of S. xylosus inoculated in by-products from the poultry industry

A wide variety of by-products are produced by the industry when animals are slaughtered. However, the proteins present in these by-products, are not being fully useable, in the elaboration of value-added products. Staphylococcus xylosus is commonly used as a starter culture in meat products subjected to ripening for a long period, as it produces proteolytic and lipolytic enzymes that improve the sensory quality of the products. Ultrasound (US) has been arousing interest in the meat industry, as it reduces processing time and also improves the technological and sensory quality of meat products. However, the stimulate effect of US on the growth of S. xylosus in by-products from the poultry industry is still unknown. Thus, this study aimed to evaluate the stimulate effect of US on the growth of S. xylosus inoculated in by-products from the poultry industry. S. xylosus was inoculated (5.63 log CFU/g) in sterilized by-products from the poultry, which were then sonicated at 37 °C for 0, 15, 30, and 45 min according to the following parameters: frequencies of 130 and 35 kHz, amplitudes of 50% and 80% and normal and degas operating modes. The sonicated samples were incubated at 37 °C for 0, 24, 48, and 72 h. Soon after sonication, no stimulate effect of US was observed on the growth of S. xylosus. However, after 24 h of incubation, the samples sonicated for 15 and 30 min in normal mode, at 35 and 130 kHz, and amplitudes of 50 and 80% exhibited better stimulate effect at the growth S. xylosus counts (p < 0.01) when compared to the Control, with values of 8.23 and 7.77 log CFU/g, respectively. These results can be exploited to obtain new added-value products, having as raw material by-products from the poultry industry.

•

We studied the effect of US on the growth of S. xylosus in poultry waste.

•

Frequency, amplitude and US time had a great impact on the growth of S. xylosus.

•

Constant ultrasonic waves stimulated the growth of S. xylosus.

•

This study found a promising new field of application for US in the meat industry.

A Setup for Microscopic Studies of Ultrasounds Effects on Microliters Scale Samples: Analytical, Numerical and Experimental Characterization

Sonoporation is the process of cell membrane permeabilization, due to exposure to ultrasounds. There is a lack of consensus concerning the mechanisms of sonoporation: Understanding the mechanisms of sonoporation refines the choice of the ultrasonic parameters to be applied on the cells. Cells’ classical exposure systems to ultrasounds have several drawbacks, like the immersion of the cells in large volumes of liquid, the nonhomogeneous acoustic pressure in the large sample, and thus, the necessity for magnetic stirring to somehow homogenize the exposure of the cells. This article reports the development and characterization of a novel system allowing the exposure to ultrasounds of very small volumes and their observation under the microscope. The observation under a microscope imposes the exposure of cells and Giant Unilamellar Vesicles under an oblique incidence, as well as the very unusual presence of rigid walls limiting the sonicated volume. The advantages of this new setup are not only the use of a very small volume of cells culture medium/microbubbles (MB), but the presence of flat walls near the sonicated region that results in a more homogeneous ultrasonic pressure field, and thus, the control of the focal distance and the real exposure time. The setup presented here comprises the ability to survey the geometrical and dynamical aspects of the exposure of cells and MB to ultrasounds, if an ultrafast camera is used. Indeed, the setup thus fulfills all the requirements to apply ultrasounds conveniently, for accurate mechanistic experiments under an inverted fluorescence microscope, and it could have interesting applications in photoacoustic research.

The relation of Bleomycin Delivery Efficiency to Microbubble Sonodestruction and Cavitation Spectral Characteristics

The concurrent assessment of principal sonoporation factors has been accomplished in a single systemic study. Microbubble sonodestruction dynamics and cavitation spectral characteristics, ultrasound scattering and attenuation, were examined in relation to the intracellular delivery of anticancer drug, bleomycin. Experiments were conducted on Chinese hamster ovary cells coadministered with Sonovue microbubbles. Detailed analysis of the scattering and attenuation temporal functions culminated in quantification of metrics, inertial cavitation dose and attenuation rate, suitable for cavitation control. The exponents, representing microbubble sonodestruction kinetics were exploited to derive dosimetric, microbubble sonodestruction rate. High intracorrelation between empirically-attained metrics defines the relations which indicate deep physical interdependencies within inherent phenomena. Subsequently each quantified metric was validated to be well-applicable to prognosticate the efficacy of bleomycin delivery and cell viability, as indicated by strong overall correlation (R² > 0.85). Presented results draw valuable insights in sonoporation dosimetry and contribute towards the development of universal sonoporation dosimetry model. Both bleomycin delivery and cell viability reach their respective plateau levels by the time, required to attain total microbubble sonodestruction, which accord with scattering and attenuation decrease to background levels. This suggests a well-defined criterion, feasible through signal-registration, universally employable to set optimal duration of exposure for efficient sonoporation outcome.

Feasibility and safety of focused ultrasound-enabled liquid biopsy in the brain of a porcine model

Although blood-based liquid biopsy is a promising noninvasive technique to acquire a comprehensive molecular tumor profile by detecting cancer-specific biomarkers (e.g. DNA, RNA, and proteins), there has been limited progress for brain tumor application partially because the low permeability of the blood-brain barrier (BBB) hinders the release of tumor biomarkers. We previously demonstrated focused ultrasound-enabled liquid biopsy (FUS-LBx) that uses FUS to increase BBB permeability in murine glioblastoma models and thus enhance the release of tumor-specific biomarkers into the bloodstream. The objective of this study was to evaluate the feasibility and safety of FUS-LBx in the normal brain tissue of a porcine model. Increased BBB permeability was confirmed by the significant increase (p = 0.0053) in Ktrans (the transfer coefficient from blood to brain extravascular extracellular space) when comparing the FUS-sonicated brain area with the contralateral non-sonicated area. Meanwhile, there was a significant increase in the blood concentrations of glial fibrillary acidic protein (GFAP, p = 0.0074) and myelin basic protein (MBP, p = 0.0039) after FUS sonication as compared with before FUS. There was no detectable tissue damage by T2*-weighted MRI and histological analysis. Findings from this study suggest that FUS-LBx is a promising technique for noninvasive and localized diagnosis of the molecular profiles of brain diseases with the potential to translate to the clinic.

FRET-based method for evaluation of the efficiency of reversible and irreversible sonoporation

It is widely known that not all of the treated cells survive after introduction of exogenous molecules via any physical method. Therefore, it is important to develop methods that would allow simultaneous evaluation of both molecular delivery efficiency and cell viability. This study presents Förster resonance energy transfer (FRET)-based method that allows molecular transfer and cell viability evaluation in a single measurement by employing two common fluorescent dyes, namely, ethidium bromide and trypan blue. The method has been validated using cell sonoporation. The FRET-based method allows the efficiency evaluation of both reversible and irreversible sonoporation in a single experiment. Therefore, this method could be used to reduce time, labor, and material cost while improving the accuracy of evaluations.