‘Smart Bubbles’: Selective Targeting of Ultrasound Contrast Agents

Abstract

Targeted ultrasound contrast agents, or targeted ‘microbubbles’ are produced by conjugation of specific ligands into the bubble membrane targeting receptor sequences expressed on surfaces of interest in the body. This allows microbubbles to be retained at pathological sites in the vasculature even under physiological flow conditions. Targeted microbubbles have great potential for diagnostic imaging of inflammation, thrombosis and angiogenesis, including the imaging of transplant rejection, deep vein thrombosis and early tumour growth. Increasingly, the application of targeted bubbles for therapeutic means is also being investigated, including microbubble-enhanced sonothrombolysis of clots and targeted drug and gene delivery. Targeted ultrasound agents could be used in future for the early diagnosis of disease states such as atherosclerosis, thrombosis and organ transplant rejection. The possibility of combining the bubbles site-specific imaging applications with their potential role as therapeutic vectors makes targeted microbubbles a very promising area of research.