Figure 4.

Sub-5 nm nanoparticles are renally clearable with clearance efficiency controllable based on the size and surface properties. A: The renal clearance efficiencies of Au_10–11, Au₁₅, Au₁₈ and Au₂₅, 1.7 nm (Au₂₀₁), 2.5 nm (Au₆₄₀) and 6 nm (Au₈₈₅₆) GS-AuNPs 24h post injection over the number of gold atoms. Below Au₂₅, the renal clearance efficiency exponentially decreased with the decrease of the number of gold atoms in the NPs (adopted with permission from reference 74). B: Illustration of the components of glomerulus. The glomerular filtration membrane is composed of multiple layers: endothelial glycocalyx, endothelial cell, glomerular basement membrane (GBM) and podocyte (adapted from with permission the reference 74). C: T₁-weighted (top row) and T₂-weighted MRI shows the time-dependent contrast changes in the bladder of a mouse injected with 3-nm core uIONP, as renally excreted uIONP slowly filling the bladder (adopted from reference 27 with permission). (D: 3D volume-rendered CT images of a mouse injected with GSH coated Ag₂S nanoparticles with an average core diameter of 3.1 nm. Green circles indicate the bladder which was filled by CT-sensitive Ag₂S nanoparticles 5 minutes after the injection. Hearts and kidneys are labeled H and K, respectively (adopted from the reference 43 with permission from the authors).