ABSTRACT
A precedent for scattering-based protein-shelled microspheres exists for cardiovascular ultrasound imaging. Air-or perfluorocarbon-filled microspheres24
have been used as scattering echogenic contrast agents to enhance the blood-tissue contrast within the cardiovascular system25 and, more recently, for identifying tumor vasculature26. Since OCT detects scattering changes, this goal can be achieved by delivering highly scattering contrast agents into the tissue and allowing the agents to attach to specific regions of interest. This chapter focuses on the progress and application of engineered optical contrast agents that are microspheres 0.2-5 µm in diameter with an approximately 50 nm-thick protein shell. The microspheres are designed to incorporate in their shell and encapsulate in their core a wide range of nanoparticles and materials which alter the local optical properties of tissue. The protein shell may also be functionalized to target the agents to specific regions of interest.
