## 3 Results and Discussion  
### Structural Characterization of Nanoparticles  
The Ag nanoparticles were prepared via in-situ approach by using wet chemistry method. Silver ions removal in aqueous solutions generally produces silver particles. Figure 2 highlights the UV-visible distribution of silver NPs produced through the use of hydrazine as a reducing agent and the absence and presence of indolicidin peptide as stabilizing factor.  
The generated AgNPs possess unique optical properties due to the interaction with specific wavelengths of light. For instance, the conduction band and valence band of the AgNPs are localized very close to each other in which electrons are moving freely to increase the absorption band of the surface plasmon resonance (SPR), due to the constructive interfaces of the electrons oscillation of silver nanoparticles in resonance with the light wave [52,53]. The Optical absorption spectra of silver NPs is dominated by surface plasmon which depends on particle size, shape, state of aggregation, and the surface chemistry of the generated Ag NPs [54]. The UV-vis spectra in Figure 2 shows very broad band of aggregated AgNPs prepared in absence of indolicidin, nevertheless, in presence of indolicidin a narrow band appeared at 365 nm. These observations stated above could be attributed to the reduction process of silver ions to silver atom using hydrazine followed by anchoring between AgNPs at the cluster surface, while the amino acids of the oligopeptide protects the cluster from fusion with the next silver molecule to facilitate unique surface chemistry. This is contributed to the collective properties of the formed Ag nanoparticles. On the other hand, different amounts of the reducing agent was added which indicates no preferences in the wavelength 365 nm but significant increase in the intensity.  
The TEM micrographs in Figure 3 demonstrate the effect of the indolicidin on the AgNPs formation. For instance, in Figure 3a,c, the AgNPs prepared within the indolicidin matrix show more control over the size and size distribution of the Ag cluster formation. To compare in Figure 3b,d, the AgNPs prepared without indolicidin elucidate aggregation of the Ag clusters in morphologies of big particles.  
It is worth mentioning that the amount of the reducing agent also played an important role when the Ag nanoparticles are templated with in the oligopeptide. Table 2 indicates the differences in AgNPs characteristics depending on the amount of N\({}_{2}\)H\({}_{4}\)-H\({}_{2}\)O. The interactions between the amino acids within the oligopeptide facilitate networks matrix to template the coordinated Ag cations. These matrixes contribute to stabilize the formed AgNPs and to avoid the particles aggregations.  
Figure 3: Morphology of silver NPs prepared using 150 \(\mu\)L N\({}_{2}\)H\({}_{4}\)-H\({}_{2}\)O in the presence of indolicidin (**a**) and without indolicidin (**b**); 10 \(\mu\)L N\({}_{2}\)H\({}_{4}\)-H\({}_{2}\)O in the presence of indolicidin (**c**) and without indolicidin (**d**).  
Figure 2: UV-Vis spectra of silver colloids prepared using 150 \(\mu\)L and 10 \(\mu\)L N\({}_{2}\)H\({}_{4}\)-H\({}_{2}\)O in the presence of indolicidin. UV-Vis spectra of silver colloids prepared using 150 \(\mu\)L and 10 \(\mu\)L N\({}_{2}\)H\({}_{4}\)-H\({}_{2}\)O without indolicidin indicated in light blue.