Providing physicians with new imaging agents to help detect
cancer with better sensitivity and specificity has the potential to significantly improve patient outcomes. Development of new imaging agents could offer improved early
cancer detection during routine screening or help surgeons identify
tumor margins for surgical resection. In this study, we evaluate the optical properties of a colorful class of
dyes and pigments that humans routinely encounter. The pigments are often used in
tattoo inks and the
dyes are FDA approved for the coloring of foods, drugs, and
cosmetics. We characterized their absorption, fluorescence and Raman scattering properties in the hopes of identifying a new panel of
dyes that offer exceptional imaging contrast. We found that some of these
coloring agents, coined as "optical inks", exhibit a multitude of useful optical properties, outperforming some of the clinically approved imaging
dyes on the market. The best performing optical inks (
Green 8 and Orange 16) were further incorporated into liposomal nanoparticles to assess their
tumor targeting and optical imaging potential. Mouse xenograft models of colorectal, cervical and
lymphoma tumors were used to evaluate the newly developed nano-based imaging
contrast agents. After
intravenous injection, fluorescence imaging revealed significant localization of the new "optical ink" liposomal nanoparticles in all three
tumor models as opposed to their neighboring healthy tissues (p < 0.05). If further developed, these
coloring agents could play important roles in the clinical setting. A more sensitive imaging
contrast agent could enable earlier
cancer detection or help guide surgical resection of
tumors, both of which have been shown to significantly improve patient survival.