THREE DIMENSIONAL IMAGING OF CANCEROUS TISSUE PHANTOM USING GOLD NANORODS AS A TWO-PHOTON CONTRAST AGENT

epithelial carcinoma, surface plasmon resonance ABSTACT Two-photon imaging is a potentially powerful technique for the early diagnosis of epithelial cancer because it permits non-invasive imaging of subcellular features hundreds of microns deep into scattering tissue. Though it is possible to discriminate cancerous and healthy tissue based on two-photon imaging from endogenous fluorophores, two-photon contrast agents have the ability to increase signal-to-noise ratio, and can be targeted to molecular signatures of interest that may not be fluorescent. We investigate the use of gold nanorods as a contrast agent for two-photon luminescence (TPL) imaging, and find that we can achieve a three orders of magnitude increase in emission intensity in comparison to two-photon autofluorescence (TPAF) imaging. Gold nanorods were prepared using a seed-mediated growth method, conjugated to anti-epidermal growth factor, and labeled to A431 human epithelial skin cancer cells in a collagen matrix tissue phantom. The gold nanorods were synthesized to have a longitudinal surface plasmon resonance of 760nm, which allows for efficient absorption of near-infrared excitation light and bright two-photon luminescence [1]