Designing a Multipurpose Diagnostic Device Using Microbubbles and Microfluidics

Lipid coated, micron-sized bubbles, or microbubbles, combined with microfluidics shows promise in the biomedical field as tools for therapeutic and diagnostic ultrasound applications. The ability to modify their composition to selectively bind to specific targets by incorporating certain bioactive groups into the lipid monolayer shell allows the potential diagnosis of a multitude of conditions. As a proof-of-concept, a mixture of model targets and microbubbles were run through a microfluidic device after an incubation period. Microbubble-bound targets are separated from their unbound counterparts using acoustic focusing. Targets are separable because unique characteristics exhibited by the microbubbles when exposed to an acoustic environment, which stem from their density and compressibility. Previously, the binding mechanics between microbubbles composed of biotinylated lipids and streptavidin coated microspheres were explored with flow cytometry. Samples run through a microfluidic device and exposed to an acoustic environment demonstrated differential displacement of the microbubble bound microspheres. In this study, the objective is to optimize this procedure. A novel device such as this could provide an inexpensive point of care approach to early diagnostics of cancers involving circulating tumor cells which is currently difficult due to low concentrations.