Stability analysis of monodisperse microbubbles composed of different lipid formulations

Monodisperse microbubbles (MDMBs) have shown great potential in ultrasound imaging and therapy. MDMBs can be fabricated directly by microfluidic chips. The Ostwald ripening is related to the stability of MDMBs, which may be dependent on the low lipid packing density in the flow channel and microbubble collection method. The role of different lipid types in the stability of MDMBs remains unclear. This study aims to analyze the stability of MDMBs composed of different lipid formulations. After the primary Ostwald ripening, DAPC-based MDMBs would undergo severe secondary Ostwald ripening in the first 30 minutes compared with other two kinds of MDMBs. All three kinds of MDMBs kept stable during 1 day, indicative of the completion of secondary Ostwald ripening and no dissolution occurrence. During 1-4 days, DPPC-based MDMBs exhibited more unstable than DSPC-based MDMBs, suggesting DPPC-based bubbles have weaker resistance to dissolution. These results showed that DSPC-based MDMBs exhibited higher stability than DPPC- and DAPC-based MDMBs.