Development of UV Shape-Changing Polymer Ultrasound Contrast Agents for Biomedical Applications

Microbubbles, as contrast agents and drug carriers, have been widely used for theranostic applications with ultrasound technology over the past three decades. Research in microbubbles has undergone numerous improvements from a compositional perspective as researchers aim for enhanced targeted drug delivery. Microbubbles shells, which typically encapsulate a gaseous core, are conventionally classified into three type's proteins, lipids, and polymers. Microbubbles will volumetrically oscillate or crack in an ultrasound field, which can be useful in targeted drug delivery applications. Polylactic Acid (PLA) can be used to fabricate microbubbles; drugs of interest can be encapsulated into the polymer shells. They can be released at the site with the application of ultrasound to achieve targeted drug delivery. However, two limitations encountered with this microbubble are a lack of controlled drug release upon triggering and the elasticity of the polymer shell in an ultrasound field. This research is focused on the development of novel Ultraviolet (UV) sensitive shape changeable polylactic acid (PLA) microbubbles to control shell properties by incorporation of a Poly (beta-aminoester) containing Azobenzene (ABP). We propose that the unique contrast agent developed in this study can be tuned to control shell elasticity and shell porosity for imaging and drug release in vivo, as well as other biomedical applications.