Green Method for Synthesis of Gold Nanoparticles Using Polyscias scutellaria Leaf Extract under UV Light and Their Catalytic Activity to Reduce Methylene Blue

Abstract

The aqueous fraction of Polyscias scutellaria leaf extract (PSE) has been used as a reducing agent and stabilizer in the green synthesis of gold nanoparticles (AuNPs). UV-Vis spectrophotometry, particle size analyzer (PSA), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy-selected area electron diffraction (TEM-SAED), and X-ray diffraction (XRD) were used to characterize AuNPs. The AuNPs have a size of 5-20 nm and have a face centered cubic (fcc) crystal structure and are stable for 21 days. Phenolic compounds, which are secondary metabolites of PSE, act as an active compound to reduce Au 3+ion to Au 0 , as well as stabilize the AuNPs through their surface interaction with carbonyl and hydroxyl groups of phenols. AuNPs exhibit excellent catalytic activity for the reduction of methylene blue with NaBH 4 . The reduction of methylene blue using AuNPs catalysts is a pseudo-first-order reaction with a reduction rate constant ( obs ) of 0.0223 min −1 .

<p>The In Vitro Immunomodulatory Effects Of Gold Nanoparticles Synthesized From <em>Hypoxis hemerocallidea</em> Aqueous Extract And Hypoxoside On Macrophage And Natural Killer Cells</p>

“…A sharp increase in absorbance (up to about 1.1 absorbance units) was detected between 0 and 20 mins, however the increase in absorbance from 20 to 120 mins was moderate since the absorbance units only increased from 1.1 to 1.25 over this time period (Figure 1B). Yulizar et al, suggested that an increase in absorbance reflects an increase in AuNP number 48. This implies that the number of Hy-AuNPs increased over the 120-min time period, but that the formation of new seeds (nucleation) of Hy-AuNPs occurs mainly within 20 mins from the start of the reaction.…”

“…Moreover, the absorbance peaks produced at 10, 20 and 40 mins also appeared to be much broader. Yulizar et al, also suggested that the shape of absorbance peaks is mainly determined by the morphological characteristics of the AuNPs 48. It can, therefore, be postulated that the growth of Hy-AuNPs, which follows the nucleation step, occurs after 20 mins, reaching the final energetically stable form at 120 mins.

Figure 1Optimization of reaction time for the synthesis of AuNPs using hypoxoside (i.e.

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Microscopic Techniques for the Analysis of Micro and Nanostructures of Biopolymers and Their Derivatives

“…SAED has been used in the analysis of biopolymers to obtain information regarding their crystalline structure [184][185][186][187]. However, SAED is proven to be a more prominent technique in the analysis of the biopolymer-assisted synthesis of metallic nanoparticles [22,23,[188][189][190][191]; SAED analysis of biopolymer gum guar capped silver nanoparticles revealed information about the crystalline structure of the nanoparticles. The diffraction pattern ( Figure 12) consisted of concentric rings with bright dots, which suggests that the synthesized particles are highly crystalline in nature; the rings were further assigned to (111), (200), (220), and (311) planes of the face-centered cubic structure of the particles [192].…”

Effect of Concentration of Imperata Cylindrica L Leaf Extract on Synthesis Process of Gold Nanoparticles

“…Indicated by the shift of the hidroxyl group at wavenumber 3354 cm -1 to 3390 cm -1 shown in Figure 3(a). The presence of more electronegative oxygen at carbonyl group that interaction with Au 0 induce a shift wavenumber of 1720 cm -1 to 1751 cm -1 so that it takes more energy to perform vibration in group C=O [17].…”