GNRred was dispersed to obtain a 0.5mgmL_1 dispersion in water/NH3 (1% v/v) by ultrasonication in a bath for 30 min, followed by tip sonication using a VCX130, (Sonics, Newtown, USA) for 2 minutes and applying 130W. GNRox was dispersed 0.5 mgmL_1 in water by ultrasonication in a bath 30 min.