To fabricate the nanobubble-based contrast agent, the researchers first ultrasonicate a mixture of Span 60 and polyoxyethylene 40 stearate and then use differential centrifugation to isolate the relevant subpopulation from the parent suspensions.

Excellent power Doppler enhancement was found in vivo in renal imaging following intravenous injection of the team's nanobubble contrast agent. The tiny bubbles are small enough to leak through the vascular pores of the tumour and accumulate in the tumour tissue by means of passive targeting due to the higher permeability of tumour blood vessels compared with normal tissue vasculature. After extravasations, an increased acoustic signal is obtained from the accumulated nanobubbles, providing strong ultrasound contrast imaging.

In addition to diagnostic applications, the nanobubbles show great potential as ultrasound-mediated drug-delivery vehicles to facilitate drug release and extravascular delivery.

More details can be found in the journal Nanotechnology.