Biomarker Targeting Molecular Contrast Agents for Ultrasound Imaging

The majority of cancer types are characterized by forming tumors which require medical diagnosis and imaging. Ultrasound is a convenient imaging option and can be used for noninvasive diagnosis, but this requires a targeting contrast agent to find and mark the cancer cells of interest. In this study, we developed an ultrasound molecular contrast agent by conjugating antibodies (mAb) and gas vesicles (GV) using click chemistry making a mAb-GV to bind to cancer cell markers. We confirmed the expression of transfected cells with Western blot. The targeting specificity of mAb after a click reaction was tested by labeling mAbs with Alexa Fluor 647 before visualizing them on cells using a fluorescent microscope. The transfected cells express green fluorescent proteins (GFP) when transfected successfully, allowing for a confirmation of expression and targeting. Next the mAbs were conjugated to GVs, targeted to cells, and image with ultrasound. Our results show precise antibody targeting and significant GV detection indicating cancer cells marked and identified using ultrasound.