Acoustically driven shear mechanoporation for efficient intracellular delivery and transfection

Delivery of large and structurally complex molecules into cells is useful in numerous biomedical applications. Furthermore, this capability is critical to the emerging area of cell-based therapeutics. Extant in vivo (viral) and in vitro (chemical, electrical) methods are often inadequate for protein, nucleic acid, and synthetic nanomaterial delivery, leading researchers to develop alternative physical approaches. Over the past two decades, our lab has established a micromachined ultrasonic droplet generator that uses geometric focusing of acoustic waves to break the liquid surface and form extremely fine droplets. More recently, we have found that these focused mechanical forces generated on a microsecond time scale can be applied to reversibly disrupt the membranes of cells. Acoustic shear poration (ASP) relies on cell ejection from microscale orifices only slightly larger than the cells to open transient pores large enough for passage of small to large macromolecules at greater than 75% efficiency. I will discuss the principles of device operation, the connection between operating parameters and treatment outcomes, and the limitations of diffusive delivery following mechanoporation. I will also introduce a two-stage approach that combines mechanoporation and an electrophoretic action to improve transfection and delivery of complex assemblies that carry multiple payloads.