“…In the evaluation of the in vivo toxicity of chitosan-coated Co 2+ -doped NaYF 4 :Yb, Tm nanoparticles conducted by Shen et al, 584 heart, liver, spleen, lung, and kidney from mice injected with the nanoparticles were harvested and assessed. Microscopic images reveal that organ structures remained normal, inflammation was not observed, and there were no significant increases in leukocytes such as lymphocyte, macrophage, neutrophil, and eosinophil, suggesting no increased immune response.…”