# Biosynthesis of Silver Nanoparticles Using _Tabernaemontana ventricosa_ Extracts
## 3 Results and Discussion
### High-Resolution Transmission Electron Microscopy (HRTEM) Analyses  
High-resolution transmission electron microscopy was used to characterize particle shape, size, and morphological distribution of synthesized AgNPs from _T. ventricosa_ leaf and stem extracts (methanolic, fresh, and powder). The HRTEM micrographs displayed in Figure 5 show similarities in the particle shape of synthesized AgNPs across all extracts, and the majority of the particles are spherical and ovate. Interestingly, the images also display hexagonal (Figure 5A-C) and triangular-shaped (Figure 5A,B,E) particles, which appear randomly distributed across a few samples. However, the triangular-shaped particles are particularly distinguishable within the powdered leaf AgNPsP samples (Figure 5E). The particle shapes observed in the present study are comparable to reports by [PERSON] et al. [2] and [PERSON] et al. [29]. In both these studies, the researchers investigated the particle shape of synthesized AgNPs using _T. divaricata_ leaf extracts, which exhibited spherical-shaped particles and similarly highlighted infrequent appearances of triangular-shaped particles [2; 29]. However, in contrasting studies, [PERSON] et al. [41] observed rod-like structures with an average particle size of 40-57 nm. The average particle size of the synthesized AgNPs ranged from 16.09 \(\pm\) 6.81 nm to 80.26 \(\pm\) 24.93 nm and differed among all samples (Figure 6). The larger average particle sizes were observed for both fresh leaf (64.01 nm) and powder stem (80.26 nm) extracts, whereas smaller particle sizes were observed predominately in the leaf (18.80 nm) and stem methanol (23.86 nm) extracts followed by the fresh stem (23.02 nm) and powder leaf extracts (16.09 nm). Overall, the synthesized AgNPs varied significantly in particle size among the different extracts, since the methanol extracts produced much smaller AgNPs followed by the fresh extracts and the powder extracts (Figure 6). Studies suggest that the average particle size of AgNPs could be related to the highly variable morphology of NPs that is often influenced by the various plant organs and extract types used during synthesis [2; 15]. The size of the AgNPs appears to be following other reports within the genus since previous studies using _T. divaricata_ leaf extracts observed an average AgNP size that ranged from 10 nm to 50 nm [2; 41; 29]. The morphological distribution of a majority of the AgNPs was well separated (not in direct contact) and monodispersed (Figure 5), suggestive of the stabilization of the NPs by their respective capping agents [2; 51]. Moreover, the HRTEM images revealed a slight film surrounding the AgNPs produced using both plant organs. According to [PERSON] et al. [25], the observed films are possibly functional groups that serve as capping agents of the synthesized AgNPs. Additionally, it is suggested that the capping of functional groups may offer extra stability to the AgNPs in the solution [8]. Moreover, it has been reported that the properties of AgNPs such as size (<100 nm) and shape (spherical, ovate, and triangular) are well suited for their effectiveness against biological processes within microorganisms [7]. Figure 5: High-Resolution Transmission Electron Microscopy images of Ag nanoparticles synthesized using methanolic, fresh, and powdered leaf and stem extracts from _T. ventricosa._ (**A**) Leaf methanol (LM); (**B**) Stem methanol (SM); (**C**) Fresh leaf (FL); (**D**) Fresh stem (FS); (**E**) Powdered leaf (PL); and (**F**) Powdered stem (PS). Arrows indicate film surrounding AgNPs. Figure 6: Particle size (nm) of synthesized AgNPs using methanolic, fresh, and powdered leaf and stem extracts from _T. ventricosa_. (**A**) Leaf methanol (LM); (**B**) Stem methanol (SM); (**C**) Fresh leaf (FL); (**D**) Fresh stem (FS); (**E**) Powdered leaf (PL); and (**F**) Powdered stem (PS). \(n\) = 5.