Investigation into the Acoustic Transparency of Reconstituted Mucus

Ultrasound (US) smart capsules are being developed with the potential to deliver medication via sonoporation in the intestine. However, a layer of mucus that can represent a barrier lines the luminal surface of the intestine. Consequently, it is important to study the propagation of US through mucus to the underlying mucosal cell layer. In order to promote sonoporation, it must be ensured that US propagates efficiently though the mucus, reaches sonoporation agents, such as microbubbles, and thus promotes cavitation. The objective of this work was to investigate the acoustic transparency of mucus. A 7 mm thick layer of mucus caused attenuation of 0.93 ± 0.16 dB/cm for a 4 MHz US signal. When controlled for the thickness of the mucus in the small intestine, mucus reduced the signal amplitude by 0.01 – 0.2%. Notably, the outcomes of this work are also relevant to US therapeutic devices acting in other cavities lined by mucus, such as the respiratory, excretory and female reproductive tracts.