Light-absorbing properties, stability, and spectral stabilization of indocyanine green

Abstract

The absorption spectrum of indocyanine green depends on the nature of the solvent medium and on the dye concentration. Binding to plasma proteins causes the principal peaks in the absorption spectrum to shift about 25 nm toward the higher wavelengths. The much greater influence on the spectrum of the dye concentration results from progressive aggregate formation with increasing concentration. Indocyanine green solutions therefore do not follow Lambert-Beer's law above 15 mg-I-1 (in plasma). Indocyanine green solutions in plasma and concentrated (1,000 mg-I-1) solutions in distilled water are stable for at least 4 h. In long-term experiments the optical density of indocyanine green solutions in plasma as well as in distilled water generally diminishes, even in the dark. On the 7th day a new absorption maximum starts to appear at gamma=900 nm, possibly caused by further aggregate formation leading to much larger particles. Spectral stabilization after injection of a concentrated solution into the blood is most rapid when the dye is dissolved in distilled water. Spectral stabilization slows down with decreasing temperature. As rapid spectral stabilization is essential in quantitative dye dilution studies, the practice of adding a albumin and/or isotonic saline solution to the injectate should be discontinued. When a 10 g-1(-1) aqueous solution of indocyanine green is used, spectral stabilization takes less than 1.5 a (at 37 degrees C), which is sufficiently fast for almost any application.

Cardiac output measurement by pulse dye densitometry in cardiac surgery

“…It is well known that solutions containing sodium sulphide, particularly in combination with heparin, can decrease the clearance of indocyanine green [25], but this alteration of clearance has no relevance in cardiac output determination using indocyanine green [25][26][27]. The influence of haemodilution on the pharmacokinetics of indocyanine green has not been thoroughly investigated.…”

Near‐infrared imaging of breast cancer using optical contrast agents

“…At higher concentration (e.g. 1290 mM) a second and dominant absorption peak is observed at around 700 nm [76].…”

“…The absorption spectrum of the dye is dependent on the solvent and the dye concentration. In plasma, the excitation wavelength is around 805 nm, the emission wavelength about 830 nm [76]. In contrast, in aqueous solution the absorption maximum is at around 785 nm.…”

Molecular Building Blocks and Their Architecture in Biologically/Environmentally Compatible Soft Matter Chemical Machinery

“…However, these techniques have only scarcely provided tissue markers that can be injected from within the digestive tract by an endoscopic instrument and visualized from the outside. In addition, near-infrared NIR fluorescent molecules, such as indocyanine green ICG 90 , have drawn much attention because the NIR light can permeate organ tissues and can be excited and detected with a fluorescence CCD camera. Furthermore, ICG has been approved by the Food and Drug Administration in the United States.…”