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Updated: Jun 13, 2026
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Transient Optical Clearing Using Absorbing Molecules for Ex Vivo and In Vivo Imaging
Published on: July 11, 2025
Tartrazine Clears Live Cells while Preserving Viability at High Refractive Indices and Osmolality
Xuandi Hou1,2, Sa Cai1,2, Han Cui1,2
1Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.
Bioconjugate Chemistry
|June 11, 2026
Summary
Tartrazine enables live-cell clearing by adjusting refractive index (RI) up to 1.41. This method preserves cell viability even under high osmolality, advancing optical imaging of living tissues.
Area of Science:
- Biomedical Optics
- Cell Biology
- Tissue Engineering
Background:
- Tissue-clearing techniques enhance optical imaging but face limitations in live systems due to toxicity and component removal.
- Previous studies suggest absorbing molecules like tartrazine and protein solutions for live tissue and cell clearing, but optimal conditions remain unclear.
Purpose of the Study:
- To systematically investigate the relationship between medium refractive index (RI) and optical contrast in cultured mammalian cells.
- To assess the impact of hyperosmolality on cell viability during optical clearing.
- To evaluate tartrazine as a live-cell clearing agent under varying RI and osmolality.
Main Methods:
- Cultured mammalian cells were used to examine optical contrast dependence on medium RI.
- The effects of hyperosmolality on cell viability were studied.
- Tartrazine was employed as the clearing agent, with RI and osmolality systematically varied.
Main Results:
- Contrary to previous findings for suspended cells, densely packed adherent cells showed decreased phase contrast up to RI 1.41 with tartrazine.
- Cultured cells maintained minimal deformation and negligible viability loss for 30 minutes, even under hyperosmotic conditions (~1200 mOsm/kg).
Conclusions:
- Tartrazine facilitates effective live-cell clearing at RI up to 1.41 while maintaining cell viability under elevated osmolality.
- These findings support further research into optimizing conditions for *in vivo* optical clearing using tartrazine.
