## 3 Results and Discussion
### The Morphology and Dimension of AA.AgNPs and SD.AgNPs  
The TEM micrographs of AA.AgNPs and SD.AgNPs were shown in Figure 4a,b. The AA.AgNPs were observed in clusters and almost oval shape (Figure 4a). The size of AA.AgNPs was estimated using image) software that was in the range of 8-52 nm and showed the average diameter of \(30.5\pm 9.4\) nm. In the earlier study of [PERSON] et al. [40], the sizes of _A. aspera_ leaf broth-mediated AgNPs were from 7 to 14 nm, and their morphology were mostly scattered and polydispersed. These different dimensions and morphologies of silver nanoparticles biosynthesized from the _A. aspera_ leaf broth were recognized by the geographical location of _A. aspera_. The plants and their phytoconstituent amounts/compositions were effected by weather and soil, _A. aspera_ leaf collected from India [40] with different reducing power formed the silver nanoparticles that were not the same as AA.AgNPs. The other reason might be because of the various extracting times leading to varying reductant concentrations. Then, we utilized  
Figure 3: Schematic illustration of biosynthesized silver nanoparticles (AA.AgNPs and SD.AgNPs) capped by phytoconstituents through carboxyl, hydroxyl, quinone and catechol groups and silver interactions.  
another plant of _S. dulcis_ to see how the difference was between two kinds of silver nanoparticles. The SD.AgNPs (Figure 4b) were smaller than AA.AgNPs. In fact, the estimated size of SD.AgNPs was in the scale of 5-45 nm, and their average diameter was 23.1 \(\pm\) 9.2 nm. About the morphology, many small SD.AgNPs were nearly of spherical shapes, some bigger SD.AgNPs were of various shapes including oval, quadrilateral, hexagonal and triangle morphology. Additionally, another similar study in India reported that the _S. dulcis_ L. leaf extract assisted in forming the AgNPs in the range of 3-18 nm [41]. Again, the same plants from different countries might be different in phytoconstituent compositions and the amounts that led to the formation of AgNPs of different sizes and shapes.  
To observe the nanoparticle surfaces, the SEM microscopy was applied, SEM micrographs of the AA.AgNPs and SD.AgNPs were shown in Figure 4c,d. Most of the nanoparticle surfaces were smooth, the agglomeration could be seen but were still less than the 100-nm clusters. So, using the AA.ext extract, we could obtain the AA.AgNPs distributed in the wide size range and there was more agglomeration than when using the SD.ext extract. These size and morphology results of AA.AgNPs and SD.AgNPs agreed with their UV-vis spectra (Figure 2a,b, solid line). AA.AgNPs had a larger diameter and more clusters than SD.AgNPs, the UV-vis spectrum of AA.AgNPs was broadened more than that of SD.AgNPs. Indeed, these results agreed with [PERSON] et al.'s study [42]. The smaller nanoparticles exhibit an absorption, the larger sphere shows increased scattering and shifted to a longer wavelength or broader peak [43]. In the case of the situation where the nanoparticles aggregate, the electrons on the surface of adjacent nanoparticles can delocalize and be shared together, which leads to the decrease of surface plasmon resonance energies. As a result, the UV-vis peak is also scattered or shifted to a longer wavelength.