‘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.