Effects of a DMPC molecular film surrounding microbubbles on the sound-pressure threshold for collapse

We investigated the effects of a 1,2-dimyristoyl-sn-glycerol-3-phosphocholine (DMPC) molecular film surrounding microbubbles on their collapse under ultrasound irradiation. We defined the ejection of the internal gas from the microbubble (i.e. “daughter” bubbles) as bubble collapse. In particular, we measured the sound-pressure thresholds for microbubble collapse in water and a DMPC solution. Bubbles with the DMPC film had a smaller resonance size than naked bubbles. The measured contact angles of the bubbles were lower after collapse, implying that DMPC molecules on the bubble surface partially desorbed between the processes of vibration and collapse.