Effect of Ultrasound and Microbubbles on Blood Flow and Particle Diffusion across Vasculature

Speaker: Christine Tarapacki, M.Sc. candidate
Department of Physics, Ryerson University
Advisor: Dr. Raffi Karshafian

Abstract: Many studies have been performed exploring the effect of ultrasound and microbubbles on drug delivery to tumour sites. Sonoporation is a mechanical method that combines ultrasound and microbubbles to temporarily damage vasculature resulting in enhance local permeability. This provides a means for drug delivery to target regions. Combining sonoporation with anti-vascular agents can induce a local vascular shutdown trapping particles inside the tumors. This would be beneficial for thermal treatments such as gold nanorod (GNR) thermal therapy which exposes GNR to specific laser conditions that generate heat in surrounding tissues. GNR are favourable because they have low toxicity and can be tuned to have a very high absorption in the optical window; wavelengths of light in the near infrared range that have a relatively low absorption in living tissues. Although GNR absorb a significant amount of energy directed towards them, surrounding blood flow acts as a heat sink to minimize temperature changes. For this reason a temporary destruction of vasculature will allow for a more effective treatment.

To study the vascular effects of ultrasound and microbubbles the Chorioallantoic membrane (CAM) model (fertilized chick egg) will be used. This in vivo model allows for vascular changes to be visualized and monitored continuously through time. In addition, different vascular concentration and complexity can be chosen based on the age of the embryo. CAM experimentation will allow for real time imaging of sonoporation and can provide insight into drug delivery mechanism and vascular damage.