Sokolova V, Nzou G, van der Meer SB, Ruks T, Heggen M, Loza K, Hagemann N, Murke F, Giebel B, Hermann DM, Atala AJ, Epple M. Ultrasmall gold nanoparticles (2 nm) can penetrate and enter cell nuclei in an in vitro 3D brain spheroid model. Acta Biomater. 2020 07 15; 111:349-362.