Stabilization of the optical tracer agent indocyanine green using noncovalent interactions

Indocyanine green is a medically useful dye that absorbs and fluoresces in the near infrared and has been sporadically employed clinically as an optic al tracer agent for liver function evaluation and cardiac output measuremen ts. The poor stability of this dye in aqueous solution, especially at the h igh concentrations needed for bolus injection, has been a hindrance in clin ical application. However, by using carefully chosen macromolecular additiv es, the stability of these aqueous dye solutions may be enhanced significan tly. Such noncovalent binding between dye and carrier molecules was found t o preserve substantially the dye in aqueous solutions for several weeks wit h no apparent changes in the measured in vivo biological properties.