Metal-enhanced emission from indocyanine green: a new approach to in vivo imaging

Abstract
Indocyanine green (ICG) is a tricarbocyanine dye (Scheme I) with near-infrared (NIR) absorption and emission maxima near 780 and 820 nm, respectively. In addition, ICG is not toxic and is approved by the U.S. Food and Drug Administration for use in humans, typically by injection. ICG has a large number of medical applications, including retinal angiography1 2; measurement of plasma volume,3 cardiac output,4 and photocoagulation5; assessment of burn depth,6 liver function,7 and exercise physiology8; and guiding biopsies.9 ICG is also being investigated for other uses such as optical tomography10 11 and optical tumor detection.12