## 5 Application  
In the past decades, silver nanoparticles have been applied to many areas because of their excellent optical properties. The three methods introduced in this essay can not only control the shapes and sizes of silver nanostructures well, but also their LSPR properties, leading to more potential applications. As mentioned in Section 1.1, [PERSON] _et al_. have synthesized silver nanoflags which combine a nanowires and a triangular nanoplate by a double reductant method as shown in Figure 4. [PERSON] _et al_. [112] studied \begin{table}
\begin{tabular}{c c c c c} \hline
**Core-Shell** & **Atomic Radius** & **Bond Dissociation** & **Electronegativiy** & **Experimental Observation** \\  & **r\({}_{\text{core}}\) vs r\({}_{\text{shell}}\)** & **Energies** & **(Paulings)** & **of Epitaxial Growth** \\ \hline Pt @ Au & small & high & low & no \\ Pt @ Ag & small & high & high & no report \\ Pt @ Pd & large & high & high & yes \\ Au @ Pd & large & high & high & yes \\ Au @ Ag & equal & high & high & yes \\ Au @ Pt & large & low & high & no \\ Ag @ Pd & large & high & low & no \\ Ag @ Au & equal & low & low & no \\ Ag @ Pt & large & low & low & no \\ Pd @ Au & small & low & low & no \\ Pd @ Ag & small & low & high & no report \\ Pd @ Pt & small & low & low & no report \\ \hline \end{tabular}
\end{table} 
Table 1: Comparison of physical constants between the core metal and the shell metal in various combinations of binary metal nanocrystals (reprinted with permission from [107]. Copyright (2008) American Chemical Society). Figure 12: **(a)** Curves a–c plot the relationship between \(|\)Emax\(|\) and the wave-length for long nano-flags (L = 2 um) with W = 150, 200, and 275 nm, respectively; **(b)** Curves a–c show the relationship between \(|\)Emax\(|\) and the wavelength for long nano-flags (L = 2 um) with W = 210, 250, and 310 nm, respectively. The inset in **(b)** illustrates the position of the focused incident light spot in the simulation model for the excitation of the long nano-flags (reprinted with permission from [112]. Copyright (2012) AIP Publishing LLC). the plasmonic properties of silver nanoflags by theoretical simulation. In their simulations they investigate the spectral properties of silver nanoflags of different widths. It can be seen from Figure 12a that resonance spectra of silver nanoflags induced by SPP mode depends on the width of the nanoplate. When the width is tuned some special values as shown in Figure 12b, the spectrum has a single resonance band with an ultra-narrow bandwidth and significant electric-field enhancement. Therefore such a nanoflag can be used in spacer-based nanolasers. The plasmonic properties of porous of Au-Ag alloy nanocages were studied by the finite element method [113]. The results show that the plasmon mode can be tunable by changing the surface porosity. When a Au nanobox transforms into a nanocage, the plasmon mode shifts red, which means that larger surface porosity causes more redshift. The simulation result is demonstrated by [PERSON] _et al_. [73]. They prepared Au-Ag alloy nanoboxes by the H\({}_{2}\)O\({}_{2}\) etching technique. In Figure 13 we see the absorption spectra of Au-Ag alloy nanoboxes (black line) and nanocages (red line). It can be seen that LSPR peaks of Au-Ag nanoboxes are red-shifted from 460, 520, 675 and 745 nm to 1210, 925, 790 and 758 nm, respectively, after the treatment with excess H\({}_{2}\)O\({}_{2}\). Because the scattering and absorption of Au nanocages can be tailored by controlling the size and porosity, [PERSON] _et al_. [114] functionalized Au nanocages with an antibody to cancer cells. In addition, they found Au nanocages have a photothermal effect when selectively attached to cancer cells, killing them by inducing localized heating. The remarkable LSPR properties of Au nanocages make them promising in the biomedical area.