Size effect of colloidal selenium particles on the inhibition of LPS-induced nitric oxide production

We have stud led the size-dependent inhibition capabilities of colloidal selenium (Se) particles on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells. Four particle sizes of the nano-Se, ranging from 45-220 nm in diameter, were examined. All of them, unlike their bulk material, show clear capabilities of inhibition and a trend dependent on the particles size. The inhbition be comes more potent as the particle size in creases. It indicates that pursuing the reduction of colloidal sizes into nanoscale is not favoured in this biological system.