Figure 1. Mimicking human skin phototype for biomedical optics.

a, PA transducer imaged melanosomes in human skins of Fitz. 5 and Fitz. 2. The scale bar represents 4 mm. b, The 3D bioprinting procedure to mimic human skin phototypes using synthetic melanin and GelMA hydrogel. Red and blue dots in the insert image are real PDA nanoparticles measured by M-NTA. c, Evaluation of skin tone impact on multiple biomedical optics (e.g., PA imaging, fluorescence imaging, and photothermal therapy). MB, ICG, Cy5.5, and gold nanorods were used to investigate the impact in different wavelengths (680–1064 nm). Insert images describe PA signal, fluorescence, and temperature of the probes under the skin-tone phantoms during the examination.