A common yellow food dye can make living animal cells completely transparent.
April 14, 2026
Original Paper
Tartrazine clears live cells while preserving viability at high refractive indices and osmolality
bioRxiv · 10.64898/2026.04.09.717314
The Takeaway
Optical clearing usually requires toxic chemicals that kill the subject. Because the food dye tartrazine (Yellow 5) is safe, we can now look deep into living, working tissues and organs in real-time without harming them.
From the abstract
Tissue-clearing techniques have transformed optical imaging of fixed specimens, yet their application to living systems remains limited by toxicity and removal of key tissue components. We recently demonstrated that absorbing molecules such as tartrazine can reversibly render live mouse skin transparent. Subsequently, it was reported that isotonic protein solutions can achieve ex vivo and in vivo cellular clearing. However, discrepancies remain regarding the optimal refractive index (RI) for liv