Fluorescent microscope system to monitor real-time interactions between focused ultrasound, echogenic drug delivery vehicles, and live cell membranes

Abstract

Rapid development in the field of ultrasound triggered drug delivery has made it essential to study the real-time interaction between the membranes of live cells and the membranes of echogenic delivery vehicles under exposure to focused ultrasound. The objective of this work was to design an analysis system that combined fluorescent imagining, high speed videography, and definable pulse sequences of focused ultrasound to allow for real time observations of both cell and vehicle membranes. Documenting the behavior of the membranes themselves has not previously been possible due to limitations with existing optical systems used to understand the basic physics of microbubble/ultrasound interaction and the basic interaction between microbubbles and cells. The performance of this new system to monitor membrane behavior was demonstrated by documenting the modes of vehicle fragmentation at different ultrasound intensity levels. At 1.5 MPa the membranes were shown to completely fragment while at intensities below 1 MPa there is a popping and slow unfolding. The interaction between these vehicles and cell membranes was also documented by the removal of fluorescent particles from the surfaces of live cells out to 20 μm from the microbubble location. The fluid flow created by microstreaming around ensonated microbubbles was documented at video recording speeds from 60 to 18,000 frames per second. This information about membrane behavior allows the chemical and physical properties of the drug delivery vehicle to be designed along with the ultrasound pulse sequence to cause the most efficient drug delivery.

The behavior of lipid debris left on cell surfaces from microbubble based ultrasound molecular imaging

“…A full description of the system is given in Ibsen et al 2012 [28] and is briefly described here. A water tank was used to acoustical couple the transducer and the Rose Chamber.…”

Use of Theranostic Strategies in Myocardial Cavitation-Enabled Therapy

“…The exploration of the ultrasonic activation of microbubbles in the circulation for therapeutic purposes continues to grow (Unger et al 2014; Aryal et al 2014; Ibsen et al 2013a; Sun et al 2014). Ultrasound microbubble-activation therapies have attractive features, including the ability to guide the treatment using ultrasound imaging, and real time feedback from the microbubble emissions (Cochran et al 2011; Kooiman et al 2014; Vignon et al 2013).…”

The influence of distance between microbubbles on the fluid flow produced during ultrasound exposure

“…The ultrasound experiments were carried out using a modified version of a custom-designed system that combined fluorescence imaging with ultrasound (Ibsen et al, 2013a). The basic system is shown in Fig.…”

“…(Color online) Schematic diagram of the microscope system used to observe and record the interaction of the fluorescent microbubbles with the focused ultrasound (figure adapted fromIbsen et al, 2013a).…”