Effect of Nano-encapsulation on Photophysical Properties of ICG

摘要

Indocyanine green (ICG) is an FDA-approved infrared chromophore used for various biomedical applications such as cardiac and hepatic function evaluation, and ophthalmic angiography. Despite its clinical applications, freely dissolved ICG binds non-specifically to various plasma proteins resulting in changes in its near infrared (NIR) emission properties and rapid elimination from the vasculature. To overcome these shortcomings, we have encapsulated ICG within polymeric nano-constructs composed of poly allylamine hydrochloride (PAH) cross-linked with di-sodium hydrogen phosphate (Na_2HPO_4). To optimize the photophysical properties of nano-encapsulated ICG (NE-ICG) for clinical imaging applications, we report measurements of fluorescent quantum yield (0) of NE-ICG. Specifically, we constructed capsules of three different diameters (～130, ～240, and ～450 nm). Our preliminary results indicate that NE-ICG shows less quantum yield compared to freely-dissolved ICG. We determined that the 240 nm diameter capsule to have the highest Φ and 450 nm diameter capsules to have the least 0 at room temperature.