Sizing Particulate Debris Ejected from Protein-Stabilized Microbubbles

Protein-stabilized air microbubbles sometimes exhibit solid-like interfaces. The high interfacial modulus allows long term stability of the microbubbles. Under certain circumstances, such as temperature and pressure changes, the microbubbles reconfigure their shape or size, expelling debris in the form of particles. The small size size and presence of remaining microbubbles complicate size determination of these particles by dynamic light scattering or even particle tracking. Instead, we studied the local diffusive dynamics of expelled particulate debris using differential dynamic microscopy. The results show the debris freely follow Brownian diffusion. DDM proves to be an easy and powerful technique for such study. This suggests potential for applications such as controlled drug release from microbubbles.