Inertial cavitation manipulation in nanoemulsion induced by low frequency acoustic wave with laser irradiation for potential therapeutic applications

Abstract

The possibility of manipulating inertial cavitation induced in a new type of nanoemulsion contrast agent with simultaneous nanosecond pulsed laser and ultrasound illumination is described. The contrast agent consists of an encapsulated emulsion core coated with a layer of 12nm-diameter gold nanospheres. A low-cost, high repetition-rate, low-energy 1064 nm fiber laser transiently heated the emulsion beads to help initiate inertial cavitation due to a phase transition in the emulsion core. It has been shown that inertial cavitation can be initiated at a very low acoustic pressure (0.43MPa) with laser irradiation applied at the rarefaction phase of the incident acoustic wave. The significantly decreased inertial cavitation threshold in this nanoemulsion suggests that it could be an effective tool for site-targeted, molecular therapeutics in addition to its proposed use as a highly specific molecular imaging agent for photoacoustics.