Ultrasound-triggered directional release from turmeric capsules

Abstract The scientific interest in capsules with the shell composed of fused microparticles is still growing due to a large number of practical applications. Well-designed capsules should ensure the safe cargo delivery and facilitate its controlled release on demand. The biocompatibility and biodegradability are additional essential features of structures intended for biomedical use. This paper presents two kinds of ultrasound sensitive capsules: the first type with the homogeneous shell made of a monolayer of fine turmeric granules, and the other with Janus shell composed of two different materials i.e. turmeric granules and synthetic polystyrene particles. We demonstrated that plane ultrasonic waves with low intensity and high frequency and also focused ultrasound can act as a trigger for smooth liberation of a liquid cargo, in our case, the dispersion of probiotic preparation. The ultrasound-induced puncture of the shell was followed by unidirectional and controlled release of encapsulated payload. In case of Janus structures, in addition to sonication time and ultrasound frequency, distinct mechanical properties of two shell regions also influenced the course of content liberation process. We expect that the use of natural material such as turmeric granules for the formation of the shells of the ultrasound-responsive capsules can further increase the range of their potential applications.