Figure 3.

(A) Schematic of the setup used for sono-photoacoustic (SPA) cavitation threshold measurements. (B) Cavitation threshold of PPy-coated emulsion contrast agents. (C) Average cavitation signal intensity as a function of negative pressure for a laser fluence of 9 mJ/cm². Cavitation events were initiated using a 1064 nm pulsed laser and a 1.24 MHz spherically focused ultrasound transducer. Cavitation of the PPy emulsion contrast agents creates transiently oscillating perfluorocarbon bubbles that can be used for contrast-enhanced imaging or therapy. The cavitation (or activation) threshold for the PPy emulsion contrast agents is significantly lower than water or PPy particles (no PFC core). The cavitation threshold for PPy emulsions decreases as lower boiling point PFCs are used as the core material. No significant differences in cavitation threshold and intensity were observed using PPy emulsions of the same PFC core but different emulsification methods (i.e. homogenization versus ouzo nucleation).