Sonoporation mediated by microbubbles has being extensively studied as a promising technique to facilitate gene/drug delivery to cells. Previous studies mainly explored the membrane-level responses to sonoporation. To provide in-depth understanding on this process, various sonoporation-induced cellular responses (e.g., membrane permeabilization and cytoskeleton disassembly) generated at different impact parameters (e.g., acoustic driving pressure and microbubble-cell distances) were systemically investigated in the present work. HeLa cells, whose α-tubulin cytoskeleton was labeled by incorporation of a green fluorescence protein (GFP)-α-tubulin fusion protein, were exposed to a single ultrasound pulse (1 MHz, 20 cycles) in the presence of microbubbles. Intracellular transport via sonoporation was assessed in real time using propidium iodide and the disassembly of α-tubulin cytoskeleton was observed by fluorescence microscope. Meanwhile, the dynamics of an interacting bubble-cell pair was theoretically simulated by boundary element method. Both the experimental observations and numerical simulations showed that, by increasing the acoustic pressure or reducing the bubble-cell distance, intensified deformation could be induced in the cellular membrane, which could result in enhanced intracellular delivery and cytoskeleton disassembly. The current results suggest that more tailored therapeutic strategies could be designed for ultrasound gene/drug delivery by adopting optimal bubble-cell distances and/or better controlling incident acoustic energy.

Reduced models of SAW-PDMS acoustofluidics need to be reconsidered especially the neglect of shear waves and interface damping.

Polydimethylsiloxane (PDMS) is widely used in acoustofluidic devices among other lab-on-a-chip systems, but a systematic study of its acoustic parameters is lacking, making it difficult to study the acoustic-PDMS interactions accurately during device designs and evaluations. Here the phase velocities and attenuation coefficients of longitudinal and shear acoustic waves propagating in Sylgard 184 samples are measured throughout the frequency band from 3.0 to 7.0 MHz. Five sample groups are prepared, corresponding to different base-agent mixing ratios $\sigma$ and curing temperatures $T$, $\left(\sigma ,T\right)=(10:1,85{}^{\circ }\mathrm{C})$, (7:1, 85 ${}^{\circ }\mathrm{C}$), (5:1, 85 ${}^{\circ }\mathrm{C}$), (10:1, 65 ${}^{\circ }\mathrm{C}$), and (10:1, 100 ${}^{\circ }\mathrm{C}$). The shear wave measurements involved examining the change of the reflection coefficient at a solid surface caused by the attachment of the samples. For longitudinal waves, the parameters are obtained by analyzing their round-trip transmissions inside double-layered solid-PDMS structures. Apart from these, the influence of sample aging on the concerned parameters are also examined. With the measured results, the parameters lead to fitted functions based on the Kramers-Kronig principle, which should benefit users working outside the studied frequency range. Finally, the two independent parameters in the elastic matrix of PDMS are provided.

Microbubble-mediated sonoporation has shown its great potential in facilitating intracellular uptake of gene/drugs and other therapeutic agents that are otherwise difficult to enter cells. However, the biophysical mechanisms underlying microbubble-cell interactions remain unclear. Particularly, it is still a major challenge to get a comprehensive understanding of the impact of cell cycle phase on the cellular responses simultaneously occurring in cell membrane and cytoskeleton induced by microbubble sonoporation.

We study dusty winds driven by radiation pressure in the atmosphere of a rapidly star-forming environment. We apply the variable Eddington tensor algorithm to re-examine the two-dimensional radiation hydrodynamic problem of a column of gas that is accelerated by a constant infrared radiation flux. In the absence of gravity, the system is primarily characterized by the initial optical depth of the gas. We perform several runs with different initial optical depths and resolutions. We find that the gas spreads out along the vertical direction, as its mean velocity and velocity dispersion increase. In contrast to previous work using the flux-limited diffusion algorithm, we find little evolution in the trapping factor. The momentum coupling between radiation and gas in the absence of gravity is similar to that with gravity. For Eddington ratio increasing with the height in the system, the momentum transfer from the radiation to the gas is not merely , but amplified by a factor of , where is the integrated infrared optical depth through the system, and , decreasing with the optical depth. We apply our results to the atmosphere of galaxies and conclude that radiation pressure may be an important mechanism for driving winds in the most rapidly star-forming galaxies and starbursts.