english: Well, a major challenge is the liver, because the liver is the body's filtration system, and the liver recognizes and destroys foreign objects, such as viruses, bacteria and also nanoparticles.
non_english: Pa, glavni izazov predstavlja jetra, jer je jetra sistem za filtraciju u telu, i jetra prepoznaje i uništava strane objekte, poput virusa, bakterija i nanočestica.