Shapiro, M.G. et al. Nat. Nanotechnol. 9, 311–316 (2014).

Though ultrasound technology has been used in research and medicine for decades, it is rarely used for molecular imaging owing to a lack of suitable nanoscale reporters. Conventional ultrasound contrast agents include gas microbubbles surrounded by a lipid or protein shell, but these reporters have several limitations, including poor stability. Shapiro et al. recently harnessed microbially produced gas vesicles, which are nanoscale compartments filled with gas and surrounded with a protein shell and are used by the organisms for buoyancy control in aquatic environments. The researchers purified the gas vesicles from the microbes and used them as ultrasound contrast agents, finding that they had high stability and were suitable for in vivo molecular imaging in mice. Further work is needed to ensure control over size and shape and to optimize circulation time and biocompatibility.