Ultrasound/radiation-responsive emulsions

The design of emulsions containing systems able to respond to different kinds of perturbations is attracting increasing interest for biomedical purposes. Emulsions of phase-change droplets, which undergo a liquid-to-gas transition on ultrasound or radiation activation are the most representative examples of such emulsions. Activation should be achieved within clinically acceptable settings, demanding a careful design of such emulsions, encompassing the selection of the components as well as the preparation procedures. New developments making use of microfluidics or low-energy emulsification methods are emerging to ensure the production of droplets of controlled size and minimal polydispersity. Furthermore, investigations on the properties of the droplets shell offer new insight for the understanding of their stability and acoustic behaviour under ultrasound irradiation. Emulsion-mediated sonodynamic therapy and the ground-breaking research on the ultrasound-propelled motors are also discussed in this review, in the light of the most recent literature.