Photophysical Properties of Indocyanine Green in the Shortwave Infrared Region

Abstract With the growing development of new contrast agents for optical imaging using near‐infrared and shortwave infrared (SWIR) wavelengths, it is essential to have consistent benchmarks for emitters in these regions. Indocyanine green (ICG), a ubiquitous and FDA‐approved organic dye and optical imaging agent, is commonly employed as a standard for photophysical properties and biological performance for imaging experiments at these wavelengths. Yet, its reported photophysical properties across organic and aqueous solvents vary greatly in the literature, which hinders its ability to be used as a consistent benchmark. Herein, we measure photophysical properties in organic and aqueous solvents using InGaAs detection (∼950–1,700 nm), providing particular relevance for SWIR imaging.