Efficiency of optical luminescence in visualization of ICG-labeled polymer implants
Astemir R. Likhov 1,, Victoria V. Zherdeva 1*, Valery V. Tuchin 2.
1 Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russian Federation; vjerdeva@inbi.ras.ru; Correspondence: vjerdeva@inbi.ras.ru (V.Z.)
2 Saratov State University, Saratov, Russian Federation, tuchinvv@mail.ru
Abstract
Optical fluorescence is used to contrast images and enhance fluorescent signal in vivo when studying subcutaneous tumors and other fluorescent objects [1].
The goal of the work was to evaluate the efficiency of optical clearing of the ICG fluorescent signal in copolymer implants using a glycerol solution. The copolymer labeled with the fluorescent dye ICG were implanted subcutaneously into Balb/c mice. A 70% aqueous glycerol solution with 5% DMSO was used as optical clearing agent (OCA), with an application time of 10 min. The images obtained before and after OCA were analyzed.
In most cases, the fluorescence intensity (FI) profile aligned at 0 min and 15 min in the initial weakly fluorescent polymers (less than 2000 a.g.) in intact tissues.
In some cases, a decrease in fluorescence signal was observed at 0-30 min with skin lesion. The phenomenon of dye quenching in glycerol has been previously demonstrated [2].
The fluorescence OC efficiency was calculated as the ratio of the integrals of the fluorescence signal areas of the ICG-labeled polymers. It ranged from negative values up to 40%.
Thus, the changes in the fluorescence signal and the luminescence efficiency can be used to judge the integrity of the skin of experimental animals.
1. Tuchina, D. K., et al (2021). Prospects for multimodal visualisation of biological tissues using fluorescence imaging. Quantum Electronics, 51(2), 104.
2. Feldman, H. et al. Fluorophore spectroscopy in aqueous glycerol solution: the interactions of glycerol with the fluorophore. Photochem Photobiol Sci 20, 1397–1418 (2021)
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Astemir Likhov
The Federal Research Centre “Fundamentals of Biotechnology” of the Russian Academy of Sciences
Russia
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Discussion
Andrey Veniaminov
What light was used for photoluminescence excitation? And what kind of polymer were the implants made of?
Astemir Likhov
Hello, the signal excitation was carried out at a wavelength of 650 nm, and the signal registration at a wavelength of 780. As for the second question, a polyester copolymer obtained on the basis of pentadiol-1,5, propylene glycol, succinic acid, and citric acid was used as a cross-linking agent (poly[pentadiol-co propylene glycol-co-(succinic acid)]). The Сopolymer contained a fluorescent label (indocyanine green (ICG)) and a paramagnetic label (gadoterate-GdDOTA).
Andrey Veniaminov
What light was used for photoluminescence excitation? And what kind of polymer were the implants made of?
Astemir Likhov
Thank you for your questions, just in case I will duplicate the answer here.
the signal excitation was carried out at a wavelength of 650 nm,
and the signal registration at a wavelength of 780.
As for the second question, a polyester copolymer obtained on the
basis of pentadiol-1,5, propylene glycol, succinic acid, and citric acid
was used as a cross-linking agent (poly[pentadiol-co propylene
glycol-co-(succinic acid)]).
The Сopolymer contained a fluorescent label (indocyanine green (ICG))
and a paramagnetic label (GdDOTA).
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