Berlin 2005 – wissenschaftliches Programm

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AK: Akustik

AK 3: Ultraschall in Biologie und Medizin (Sitzungsorganisation: Robert Lemor, St. Ingbert)

AK 3.6: Hauptvortrag

Samstag, 5. März 2005, 11:30–12:00, TU EB222

Drug Delivery from Jetting Cavitation Bubbles — •Claus-Dieter Ohl, Manish Arora, and Detlef Lohse — Physics of Fluids, University of Twente, Postbus 217, 7500 AE Enschede, The Netherlands

The usage of ultrasound to deliver non-invasively and remotely drugs to cells is becoming an emerging technology. Still, the mechanism leading to the drug uptake is unknown. Here, we demonstrate that a rather complex pathway excites the uptake of large molecules through the protective cell membrane. This is demonstrated for adherent cells on a substrate which are exposed to a single cycle of a strong ultrasound wave.

During the negative pressure part of the wave cavitation bubbles are nucleated and expand spherically. However, during the shrinkage of the bubble a well known liquid jet is formed which flows towards the substrate with the attached cells. The impinging wall jet when spreading radially on the substrate creates a boundary layer with strong shear. This shear stress when imposed on the cells causes either their detachment, permanent poration, or reparable poration of the cell membranes.

To document the sequence of events high speed sequences of the bubble dynamics and cell detachment, fluorescence and scanning electron microscopy are presented. Further, we model the kinetics of cell detachment with an analytical and a numerical solutions of the Navier-Stokes equation.