Physicochemical characterization of P. betle assisted MgO NPs
Figure 1 presented the UV-vis spectra of P. betle assisted MgO NPs. The UV-vis spectra of MgO NPs showed a single peak at 384 nm in the wavelength range of 200–800 nm. It demonstrated that MgO NPs with a surface plasmon resonance acquired in the reacted mixtures and MgO NPs were formed. The optical properties of MgO NPs were confirmed using UV- Visible spectrophotometer and peak attained at 384 nm. It was a similarity to pervious research reports (Ammulu et al., 2021; Sharma et al., 2017). And they confirmed the formation of MgO NPs by color changes and obtained a peak at 310 nm in UV- Spectrophotometry analysis.
The XRD analysis is broadly used to conclude the nature, structure and size of nanoparticles. Figure 2 shows the XRD pattern of MgO NPs synthesized by using the P. betle extract. Debye–Scherrer’s formula was employed to calculate the size of MgO NPs and which was found to be 18 nm. The obtained planes in XRD spectra were clearly reveals that bio-fabricated MgO NPs were crystalline nature. Umaralikhan and Jamal Mohamed Jaffar, (2018) were synthesized of MgO nanoparticles using aqueous leaf extracts of Pisidium guvajava and Aloe vera. They determined the nature and size of the nanoparticles by XRD analysis.
FT-IR analysis was used to find out the potential functional molecules which answerable for the capping and reduction of MgO NPs. Figure 3 refers the FT-IR spectra of MgO NPs synthesized using the P. betle extract. FT-IR shows sharp absorption peaks of 486, 699, 754, 1209, 1453, 1789, 1909, 3622 and 3919 cm− 1. The stretching vibration mode for the Mg–O–Mg moiety was observed at the peaks of 486, 699 and 754 cm− 1 (Taghavi Fardood et al., 2018). Others peaks were corresponding to O–H stretching vibration and C = O. FT-IR spectra confirms that; MgO NPs have functional groups of phytochemicals.
The surface morphology of P. betle assisted MgO NPs was determined using the SEM analysis. It revealed the regular spherical shaped morphology of MgO NPs (Fig. 4). This result agreed with pervious investigation (Nguyen et al., 2021). The elemental composition and purity of P. betle assisted MgO NPs were observed by using the EDX technique (Fig. 5). EDX spectra shows the occurrence of Mg, O and C, which confirms the formation of MgO NPs. Dobrucka, (2018) was reported the synthesis of MgO NPs using Artemisia abrotanum herba extract and synthesized MgO NPs shows presence of magnesium, other element such as carbon, calcium etc.
The thermal analysis of P. betle assisted MgO NPs was performed to assess it weight loss when increasing temperature range from 50 to 1000°C. Figure 6 and b illustrates the TGA curve of MgO NPs. Overall, 33.6% of weight loss was occurred on MgO NPs in the range of 50 to 1000°C. It refers the losses of phyto-molecules in surface of MgO NPs. This study was compare with previous report (Wong et al., 2020).
Antioxidant Assay
P. betle assisted MgO NPs was used to determine its antioxidant activity by DPPH assay (Table 1). The antioxidant activity was shows dependent on concentration of MgO NPs. The low concentration (50 µg/ml) of MgO NPs showed minimum percentage (25.8%) of free radical scavenging activity, whereas the highest concentration (500 µg/ml) of MgO NPs shows the maximum percentage (88.9%) of free radical inhibition. The highest percentage of free radical inhibition was observed in P. betle assisted MgO NPs due to presence of bioactive compounds in surface of nanoparticles. Ammulu et al., (2021) reported the synthesis of MgO NPs using Pterocarpus marsupium rox. b heartwood extract and evaluate its antioxidant activities. They concluded that, Phyto-assisted MgO NPs have good antioxidant activity.
Table 1
Antioxidant activity of P. betle assisted MgO NPs
S.No.
|
Concentration of P. betle assisted MgO NPs (µg/ml)
|
Free radical scavenging activity (%)
|
1
|
50
|
25.8 ± 0.20
|
2
|
100
|
48.9 ± 0.78
|
3
|
200
|
68.89 ± 0.99
|
4
|
500
|
92.89 ± 0.98
|