Stability and degradation of indocyanine green in plasma, aqueous solution and whole blood

Abstract

Fluorescence-based imaging has evolved into an important technology during recent years. Specifically indocyanine green (ICG) has invaded most fields of diagnostic and interventional medicine. Considering the numerous advantages of the substance like the rapid degradation and rare adverse reactions, ICG is currently the most commonly used fluorescing agent. High-performance liquid chromatography (HPLC) was used for measuring absorbance and fluorescence of ICG and its potential degradation compounds. Stability and degradation were evaluated under light exposure or in darkness at various temperatures. Under these conditions, degradation of ICG was evaluated over a period of 11 days. Additional, stability measurements of ICG were performed in EDTA whole blood samples at 37 °C incubation temperature while monitoring. Furthermore, we used mass spectrometric (MS) and nuclear magnetic resonance (NMR) analyses for the identification of supposed ICG degradation compound. Potential quenching effect of ICG was examined in aqueous and plasma solutions at concentrations ranging from 0.01-100 μg ml-1. When diluted in water and stored at 4 °C in the dark, ICG is stable for three days with only 20% of fluorescence intensity lost in this time-span. ICG incubated at 37 °C in whole blood under light exposure is stable for 5 h. In our study we observed the degradation of ICG into two degradation compounds with a mass of m/z 785.32 and m/z 1501.57, respectively. Based on our observations we suggest that ICG should be used within one or two days after preparation, if the ICG solution is stored at 4 °C.

Minimally invasive method for the point-of-care quantification of lymphatic vessel function

“…Qualitative LC-MS analysis of ICG-water incubated for 24 hours revealed the presence of a main ICG peak that eluted at 13.6 minutes (m/z = 753.42) and of a main degradation product at 12.09 minutes (m/z = 752.42) that could be assigned to an "irreversible" covalent dimer, as previously reported (42)(43)(44), as well as further smaller degradation products. In contrast, in ICG-Kolliphor HS15 solutions, the peak emerging from the plausible dimer was barely visible, even beyond 100 days after preparation (Supplemental Figures 2-4).…”

“…Increased stability of ICG in Kolliphor HS15. ICG is known to rapidly degrade in aqueous solutions, resulting in a loss of fluorescence intensity (41,42). Thus, we compared the stability of ICG in a pure aqueous solution to that of ICG in the presence of 10 mg/ml Kolliphor HS15 by measuring the fluorescence intensity of the respective dye solution over time when stored at room temperature and protected from light.…”

Isomerization and Dimerization of Indocyanine Green and a Related Heptamethine Dye

“…We could confirm the all‐ trans conformation, but also detected a small amount of a specific mono‐ cis isomer even in the absence of photo‐excitation. Furthermore, we present further evidence for the previously proposed dimerization of ICG to 3 in the presence of oxygen and under daylight exposure.…”

“…In a previous report, the stability of 1 was studied in aqueous solution, and a dimeric species 3 could be identified by DOSY NMR as the dominant degradation product . Further NMR experiments suggested that the two monomeric fragments in 3 are connected through the γ carbons of the methine chain.…”

Mutual impact of clinically translatable near-infrared dyes on photoacoustic image contrast and in vitro photodynamic therapy efficacy

“…38,46 Several studies have shown that ICG demonstrates a blueshift in absorbance peak with an increase in the concentration or in the presence of serum, water, or salt, etc. 38,[46][47][48][49] and degrades when irradiated with light. 50 Specifically, ICG undergoes conformational changes in the presence of reactive radicals that can either be self-generated or be generated by other molecules in the vicinity.…”