Manganese(II)-Guided Separation in the Sub-Nanometer Regime for Precise Identification of In Vivo Size Dependence.

A precise understanding of nano-bio interactions in the sub-nanometer regime is necessary for advancements in nanomedicine. However, this is currently hindered by the control of the nanoparticle size in the sub-nanometer regime. Herein, we report a facile in situ Mn 2+ -guided centrifugation strategy for the synthesis of large-scale ultrasmall gold nanoparticles (AuNPs) with a precisely controlled size gradient at the sub-nanometer regime. With the discovery that [Mn(OH)] + , especially metallic manganese (Mn 0 @[Mn(OH)] + ) nanoparticles, could selectively interact with larger AuNPs through synergistic coordination and hydrogen bonding to form aggregates, we also realized the fast (<1 h) synthesis of water-soluble atomically precise Au 25 with high yields (>56 %). We further demonstrated that sub-nanometer size differences (approximately 0.5 nm) significantly alter non-specific phagocytosis of AuNPs in the reticuloendothelial system macrophages, elimination rate, and nanotoxicology.