Spectral Analysis for the Detection of Nanoparticles in Optical Coherence Tomography Scans

Optical coherence tomography (OCT) is an imaging modality that is able to visualize the light backscattered from a sample and create a micron resolution tomogram of its structure. This enables very high resolution images of biological structures, such as the retina and tumors. Functional imaging of the molecular processes inside tissue has not been realized with OCT yet. One way to image molecules with OCT could be to selectively attach beacons to the molecules, for example by using antibody labeled plasmonic nanoparticles, such as gold nanorods (GNRs). We aim to detect the nanoparticles in tissue with OCT owing to their plasmonic spectral peak. This task is challenging due to the composition of the OCT signal which encodes the scattering spectrum along with the location of the scatterers. In this report we describe how we were able to detect GNRs in solution in-vitro, and in-vivo, in the blood and lymph vessels of living mice. In addition, we were able to detect more than one type of particle, based on the difference in the location of the spectral peak. This type of multiplexing could be used to image more than one molecule simultaneously in the future. Keywords—Optical coherence tomography; Gold nanorods; Molecular imaging