Thu February 7th 2008
11:00
Seminar Characterisation and design of microbubble agents for diagnostic and therapeutic applications
Eleanor Stride

Details:

Gas microbubbles coated with a surfactant or polymer shell have become well established as effective contrast agents for ultrasound imaging and their potential use as carriers in therapeutic applications such as targeted drug delivery is also under investigation. The aims of the current project are: firstly, to investigate the effect of changing the composition and structure of the microbubble coating for enhancing their detectability in vivo; and, secondly, to evaluate different processing methods for microbubble production.

A new model relating the dynamic behaviour of a microbubble to its chemical composition has been derived and used to simulate the effect of different types of coating, including multiple layered shells containing drugs. The results indicate that microbubble response can be substantially affected by drug loading and/or the addition of functional components and subsequent experimental investigations demonstrate that the effects may be reasonably well predicted and controlled. In particular, it was found that the nonlinear content of the scattered field from the microbubbles could be enhanced which may prove useful for detecting microbubbles at low insonation pressures.

The first method investigated for microbubble processing was co-axial electrohydrodynamic atomisation (CEHDA). Microbubbles were prepared using purpose-built apparatus in which a co-axial gas/liquid jet was formed and then subjected to an electric field to induce fragmentation and hence microbubble formation. Secondly, a specially designed “T-junction” device was used to prepare microbubbles by the impingement of a gas jet upon a steady liquid flow at a sharp orifice. For comparison, microbubble suspensions were also prepared by conventional sonication techniques. Phospholipid coated microbubbles prepared using CEHDA with optimised flow rates and applied voltage had diameters ranging between 3-7 µm, compared with 1-50µm for sonication. It was found that an even higher degree
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The 10th Complex Motion in Fluids 2021
AQUA
Max Planck Gesellschaft
MCEC
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