Monitoring Refractive Index Kinetics of Optical Clearing Agents in Synthetic Opal Phantoms
Arsenii P. Fashchevskii1, Yuriy I. Surkov1, Isabella A. Serebryakova1, Arsen K. Zotov2, Anna S. Kycheryavenko3, Gleb M. Katyba3, Valery V, Tuchin1,4,5
1Saratov State University, Saratov, Russia
2Prokhorov General Physics Institute RAS, Moscow, Russia
3 Osipyan Institute of Solid State Physics RAS, Chernogolovka, Russia
4Tomsk State University, Tomsk, Russia
5Institute of Precision Mechanics and Control, FRC “Saratov Scientific Centre of the RAS,” Saratov, Russia
Abstract
Measuring the kinetics of the refractive index (RI) of optical clearing agents (OCA) during the optical clearing (OC) process is an important task in biophotonics, as it reveals the mechanisms of agent penetration and distribution in complex media. In this study, we present a methodology for highly accurate determination of OCA RI. Aqueous glycerol solutions at concentrations of 70% and 90% were used as OCAs, while synthetic opals (SO)—porous matrix structures composed of closely packed monodisperse silica (SiO₂) globules—served as model systems.
The method is based on monitoring temporal changes in the optical thickness of SOs using optical coherence tomography (OCT). Additionally, mass measurements were performed for each sample in three states: dry, saturated with distilled water, and saturated with OCA. These data make it possible to calculate the kinetics of OCA RI during the clearing process.
The obtained RI–time dependence also provides access to the physical characteristics of the medium, including geometric thickness, porosity, and effective RI. To evaluate the accuracy of the proposed methodology, the results were compared using three independent approaches: RI matching, analysis with a simpler reference sample of constant thickness and well-characterized porosity, and hydrostatic weighing.
Consistency across all three methods confirms the reliability of the proposed approach. Overall, this methodology enables precise monitoring of OCA RI kinetics and related structural parameters, offering a robust tool for studying optical clearing processes in porous media.
Speaker
Fashchevkii Arsenii P.
Saratov State University
Russia
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