Lipid-coated nanodrops and microbubbles #35

Abstract

Lipid-coated microbubbles and nanodrops are used in many applications of biomedical ultrasound. They serve as ultrasound contrast agents, molecular imaging probes, targeted drug delivery vehicles, nucleic acid vectors, gas carriers, and enhancers of thermal ablation. Each application has a unique set of performance criteria - there is no "one size fits all" microbubble formulation. Rational design can be accomplished using the composition ! processing !structure ! property ! performance paradigm first described by DH Kim for lipid-coated microbubbles over a decade ago. One notable example has been the synthesis of longer circulating microbubbles through centrifugal isolation of larger diameter microbubbles coated with long acyl chain phospholipids. The purpose of this chapter is to inform the reader of current knowledge of the effects of lipid composition and processing on microstructure, as well as the effects of microstructure on important physical properties, such as microbubble size and shell viscoelasticity. More research is necessary to further elucidate these interrelationships and to exploit them for innovative microbubble designs.