Figure 2.

TEM images of GNPs with indicated size and polydispersity. They are prepared by conventional citrate method from 0.25 mM (A), 0.50 mM (B), 1.0 mM (C), 1.5 mM (D), 2.0 mM (E), and 2.5 mM (F) chloroauric acid, respectively. Scale bar: 20 nm.