Cellular uptake and phototoxicity of surface-modified fluorescent nanodiamonds

►We investigate the uptake of FND-Tf and FND-NH2 to understand endocytic processes. ►The internalization of FND-Tf is twice as efficient as that of FND-NH2. ►Cellular growth inhibition is observed following incubation of surface-modified FNDs. ►The phototoxicity of internalized FNDs is evaluated. ►Raman spectra prove that the phototoxicity of FNDs results from photothermal effect.