# Review on Silver Nanoparticles as a Novel Class of Antibacterial Solutions
## 3 Characterization Methods for Metal Nanoparticles  
In Table 2 several nanoparticles characteristics are presented along with the techniques that can be used to observe the respective characteristics (Table 2). Physical and chemical properties of nanoparticles need to be observed when trying to characterize nanoparticles. The chemical composition and concentration are not enough to distinguish nanoparticles. Their size, shape and surface properties also need to be depicted for adequate experimental reproducibility. Several methods of characterization are presented by [PERSON] et al [33]. X-ray diffraction (XRD) is one of the most used techniques to provide information about crystalline structure, nature of the phase, lattice parameters and crystalline grain size. X-ray Diffraction has been proposed only during late years for usage in nanoparticle characterisation [34]. Although it has prove it utility, some limitations have been reported, such as \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Synthesis Method** & **Chemicals** & **Size (nm)** & **Shape** & **UV-VIS** & **Ref.** \\ \hline Chemical & Silver nitrate, trisodium citrate, sodium borohydride & 15–50 & Spherical & 397 & [10] \\  & Silver nitrate, polyvinyl pyrrolidone, trisodium citrate, hydrogen peroxide, sodium borohydride, performed in a dark environment & 30–200 & Spherical & 504–735 & [10] \\  & Silver nitrate, sodium borohydride, trisodium citrate, gallic acid, tannin, hydroxyamine hydrochloride, sodium hypophosphite, sodium hexametaphosphate, sodium tripolymbnbate & 10–20 & Spherical & 390 & [25] \\ Green & Silver nitrate, extract of sumac fruits, Silver nitrate, polyvinyl pyrrolidone, sodium borohydride & 15–30 & Spherical & 438 & [26] \\ Chemical & Silver nitrate, polyvinyl pyrrolidone, sodium borohydride & 7.7 \(\pm\) 1.5 & Spherical & 403 & [27] \\ Chemical & Silver nitrate, sodium borohydride, L-cysteine & 7.6 \(\pm\) 1.6 & Spherical & 396 & [27] \\  & Silver nitrate, Polygonum cuspidatum, Fagopyrum dibotrys, sanguisorbafofficinolis, agrimoniapilosa, Hedyotsidiffusa, Rheum palmatum, Geroniummuffordii, phosporific acid, trisodium citrate & 36–55 & Spherical & 425 & [28] \\ Green & Silver nitrate, sodium chloride, hydrochloric acid, sodium hydroxide, pH 5 & 60–110 & Hexagonal & 480 & [9] \\ Green & Silver nitrate, sodium chloride, hydrochloric acid, sodium hydroxide, pH 9 & 10–40 & Spherical & 420 & [9] \\ Chemical & Silver nitrate, multi amino compound & 26 & Spherical & 400–420 & [29] \\ Chemical & Silver nitrate, L-cysteine, cetyltrimethylammonium bromide, polyvinyl alcohol & 55 & Spherical & 420 & [30] \\ Green & Silver nitrate, peptone, beef and yeast extract, sodium chloride & 14–42 & Spherical & 440 & [31] \\ Chemical & Silver nitrate, citric acid, zinc nitrate & 53.07 & Spherical & 410 & [32] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: \(Cont.\) \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Suitable Technique** \\ \hline Size & Transmission electron microscopy (TEM), X-Ray Diffraction (XRD), Dynamic light scattering (DLS), UV-Vis Spectroscopy (UV-Vis), Nuclear Magnetic Resonance (NMR) \\ Shape & Transmission electron microscopy TEM, High-Resolution Transmission Electron Microscopy (HRTEM), Atomic force microscopy (AFM) \\ Crystal structure & X-Ray Diffraction (XRD) \\ Surface charge & Zeta potential, Electrophoretic mobility (EPM) \\ Size distribution & Dynamic light scattering (DLS), Differential centrifugal sedimentation (DCS) \\ Atomic formic microscopy (AFM) \\ Optical properties & UV-Vis Spectroscopy (UV-Vis), Photoluminescence (PL) \\ Magnetic properties & Superconducting quantum interference device magnetometry (SQUID), Vibrating sample \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Nanoparticle characterization techniques. crystal growing difficulty, increased effort to obtain data on single conformation as well as it low intensity [35].