Fig. 2.

(a) Photo snapshot of the gold coated glass slide modified by electrodeposition. The reddish circular area represents the portion covered by the Au nanospikes. SEM images of Au nanospikes: (b) 30,000$\times$, top view; (c) 30,000$\times$, tilted (40${}^{\circ }$); and (d) 100,000$\times$, tilted (40${}^{\circ }$).