Molecular-targeted nanorods for the localised destruction of cancer cells

Nanorods are used to improve the signal-to-noise ratio of the thermoelastic emissions from tissue and can be functionalised with molecular-targeting ligands to be specifically targeted to cancer cells, for both imaging and therapeutic applications. By simultaneously illuminating these nanorods whilst they are under tension from an ultrasound field, localised inertial cavitation is generated at significantly lower laser fluence and pressure thresholds than for either of these mechanisms alone. The broadband acoustic emission generated with an inertial collapse can be detected, where it has been shown that the magnitude of these emissions are over an order of magnitude greater than thermoelastic emissions alone and thus have a greater depth penetration. As the inertial collapse is driven by the peak pressure of the ultrasound field it can be sufficiently violent to result in the localised destruction of cancer cells. This study has shown that the nucleation pressure threshold of vapour bubbles around gold nanorods decreased with increasing laser fluence but the magnitude of the emissions were dominated by the peak acoustic pressures used. A localised cell population that had been incubated with un-targeted nanorods was imaged using the broadband emissions from the vapour collapse, which at the exposure levels of 2.65 MPa and 1.5 mJ/cm² resulted in the cells becoming un-viable.