Ultrasound imaging is one of the most widely used medical imaging modalities because it is non-invasive, low cost and widely available. Ultrasound signals can be amplified using contrast agents that come in the form of small gas filled bubbles including microbubbles (MBs). Through new chemistry and engineering, targeted MB’s are being developed so that ultrasound imaging can be used to visualize specific biomarkers including those that indicate the presence and aggressiveness of cancers.
In the Valliant group, we are working to create new methods to target ultrasound contrast agents. This includes microbubbles that can target proteins overexpressed on tumors. Below is an example of a new MB targeting technology (Angew. Chem. Int. Ed 2014, 53, 6459-6463) that was created using bioorthogonal chemistry:
A schematic showing the use of bioorthogonal chemistry to localize ultrasound contrast agents (microbubbles – blue spheres) to tumor cells. In step 1 a transcyclooctene (TCO) functionalized antibody, which targets a biomarker on cancer cells (VEGFR2), is administered and allowed to localize at the site of the disease. The second step involves injection of tetrazine functionalized microbubbles where the TCO and tetrazine groups react (“microbubble capture”) leading to enhanced ultrasound signal at the site of the tumor (mouse images shown on the right). See Angew. Chem. Int. Ed 2014, 53, 6459-6463.