Fig. 8

The lateral size affects renal clearance pathways of GOs and selectively induces potential risk of kidney injury. Graphene oxide with different lateral sizes showed different renal excretion pathways. The s-GOs can be excreted via glomerular filtration, while l-GO tends to be excreted into urine via tubular secretion. The basolateral/influx and apical/efflux transporters may contribute to the active uptake and secretion of GOs. There are dose dependent biological responses for glomerular filtration and tubular secretion of GOs. At a low dose administration, there are no obvious pathological changes in the kidneys in response to the glomerular filtration and tubular secretion. However, at a high dose administration, s-GO administration induced obvious glomerular changes, including increase of GBM thickness, effacement and diffuse fusion of foot processes, increase of foot process width and decrease of foot process length and slit diaphragm perimeter. The tubular secretion of large amounts of l-GOs caused obvious tubular injury, such as tubular dilatation, loss of the brush border on the surface of the renal proximal tubular epithelium, appearance of tubular casts, and epithelial cell necrosis