The influence of particle size was also studied. Using S-AuNRs of 16 nm in width and 60 nm in length, the effect of the solvent composition was examined (Figure ). By adding 10%(v/v) EtOH, assembly formation was observed. No relevant differences with larger rods were noted. As the EtOH content was increased to 20%(v/v), increased packing of the assembly was observed, similar to the behavior of L-AuNRs (Figure ).