Characterization of the differently sized Au-NPs.

<p>Transmission electron microscopy (TEM) images of Au-NPs with diameters of (A) 5 nm, (B) 10 nm, (C) 20 nm, or (D) 40 nm. The insets show high-resolution images. Scale bars, 20 nm and 100 nm (as marked). E: UV-vis spectra of the Au-NPs with 5-nm, 10-nm, 20-nm, and 40-nm diameters.