Fig. 1. Illustration of live tissue clearing based on the utilization of tartrazine. (a) (i) Light propagation in an untreated mouse. (ii)–(iv) Due to the mismatch of RIs, light propagation through tissues and cells experiences strong scattering, resulting in seemingly random speckles outside the tissue sample. (b) (i) Light propagation in a mouse treated with tartrazine. (ii) With improved RI homogenization, light propagation through tissues and cells exhibits considerably suppressed scattering, enabling controllable light delivery (e.g., optical focusing) through the tissue sample. (iii) Mechanism of optical clarification achieved by tartrazine-like absorbing molecules. The gray dashed line is its absorption spectrum, and the golden solid line is its simulated RI curve; at longer wavelengths, it can effectively reduce the contrast in RI between water and lipids, realizing RI matching.