‘Transparent mice’: deep-tissue live imaging using food dyes

Light scattering, resulting from refractive index mismatch, is the primary factor limiting imaging depth in biological tissue. In a study recently published in Science¹, Ou et al. took an unconventional approach and employed highly absorbing molecules, such as food dye tartrazine, to increase the refractive index of water in the near-infrared wavelength range, which rendered tissue transparent in live mice.