The design of multifunctional microbubbles for ultrasound image-guided cancer therapy

Gas-filled microbubbles are widely used in diagnostic imaging. Recent developments have greatly enhanced the potential use of microbubbles for both diagnostic and therapeutic applications. For the potential use of microbubbles in therapeutic applications, the chemical nature of the shell and its mechanical properties are crucial, and requires a tailored synthetic approach. This review describes methods of preparation, mechanism of action, in vitro and in vivo stability and structural/functional characterization of microbubbles. New mechanisms for ultrasound-enhanced local drug and gene delivery are reviewed. Different strategies used to target microbubbles to regions of disease and some of the recent experiences in ultrasound image-guided therapy are discussed.