Experimental validation of innovative optical clearing agents for in vivo optical coherence tomography
Pavel A. Moldon1, Danila A. Umerenkov1, Polina A. Timoshina2, Yuri I. Surkov2, Andrei E. Lugovtsov1, Alexandr V. Priezzhev1; 1Lomonosov Moscow State University; 2Saratov State University, Saratov
Abstract
Introduction
The optical clearing agents (OCA) are widely used to increase the depth of light penetration into the studied biological tissues and organs and hence improve their visualization [1]. Recently, tartrazine, a common food dye, was successfully demonstrated as an effective OCA for skin imaging in living mouse in vivo [2]. This finding is highly promising for clinical translation, as tartrazine is pre-approved as a safe food additive by regulatory bodies like the U.S. FDA and the European Food Safety Authority (EFSA). Based on this, the present study aims to quantitatively evaluate the optical clearing efficacy of tartrazine on human finger phalanx tissue in vivo. Using OCT data, we directly compare the performance of tartrazine against other established OCAs to assess its potential for human applications.
Materials and methods
In this study, we used two high-resolution OCT systems: OCP930SR 022 OCT system (Thorlabs) with central wavelength 930 nm and OCS1300SS (Thorlabs) central wavelength 1325 nm. In the work 4 OCA agents were used: two tartrazine-based formulations—30% tartrazine with 0.625% hydroxyethyl cellulose and 30% tartrazine with 0.5% agarose, both in distilled water—and two glycerol-based formulations—70% glycerol, 20% propylene glycol, and 10% dimethyl sulfoxide (DMSO); 69,775% glycerol; 19,775% propylene glycol; 9,775% DMSO; 0,675% hydroxyethyl cellulose.
Results and conclusion
All tested substances demonstrated the optical clearing effect. The most significant enhancement was achieved with a mixture of tartrazine, water, and agarose, which proved effective across all depth ranges in both OCT configurations. Quantitatively, this OCA reduced the scattering coefficient by 27 ± 5% in the 0-50 µm depth range within 15 minutes of application. Furthermore, it increased the reflected light intensity from the 200-400 µm depth by a factor of 2.7 ± 0.6 after 30 minutes.
In conclusion, our results confirm that the tartrazine-based OCA is a highly effective agent for enhancing optical transparency in human skin in vivo.
This work was supported by the Russian Science Foundation (Grant No. 23-45-00027).
[1] Luis M.C., et al. “The Optical Clearing Method”, Springer Briefs in Physics (2019).
[2] Zinao Ou, et al. Achieving optical transparency in live animals with absorbing molecules // Science. USA. 2024. Vol. 385. Issue. 6713
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Moldon Pavel Aleksandrovich
Department of Physics, Lomonosov Moscow State University
Russia
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