Frequency dependence of ultrasonic effects on the kinetics of hen egg white lysozyme fibrillation

Our study aimed to investigate the effects of ultrasound on the fibrillation kinetics of HEWL (hen egg white lysozyme) and its physicochemical properties. Ultrasound, a mechanical wave, can induce conformational changes in proteins. To achieve this, we developed an ultrasound exposure system and used various biophysical techniques, including ThT fluorescence spectroscopy, ATR-FTIR, Far-UV CD spectrophotometry, Fluorescence microscopy, UV-spectroscopy, and seeding experiments. Our results revealed that higher frequencies significantly accelerated the fibrillation of lysozyme by unfolding the native protein and promoting the fibrillation process, thereby reducing the lag time. We observed a change in the secondary structure of the sonicated protein change to the β-structure, but there was no difference in the Tm of native and sonicated proteins. Furthermore, we found that higher ultrasound frequencies had a greater seeding effect. We propose that the effect of frequency can be explained by the impact of the Reynolds number, and for the Megahertz frequency range, we are almost at the transition regime of turbulence. Our results suggest that laminar flows may not induce any significant change in the fibrillation kinetics, while turbulent flows may affect the process.

Ultrasound and Sonogenetics: A New Perspective for Controlling Cells with Sound

An important challenge in neurobiology is to stimulate a single neuron, especially in deep areas of the brain. The optogenetics methods need a surgical operation to convey light sources to targeted cells. Nowadays, non-invasive tools such as sonogenetics with the ability to modulate and visualizing cellular and molecular processes have attracted much attention. The study of the biological functions of living organisms always requires tools for monitoring and imaging dynamically. Current sonogenetic approaches use ultrasound as a non-invasive tool to precisely control cellular function. In general, sonogenetics includes the development of mechano-sensitive proteins, approaches for introducing their genes to specific cells, targeted stimulation, and finally, reading the outcome. Hence, to prepare a short review of emerging technology sonogenetics, we summarized the introduction of sound waves, the mechano-sensitive proteins commonly used in sonogenetics, and potential therapeutic applications of sonogenetics for biological research and medicine. This short review would beneficiate in the translation of sonogenetics from present in-vitro and in-vivo investigations to clinical therapies.