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. 2020 Jul 22;7(7):200065.
doi: 10.1098/rsos.200065. eCollection 2020 Jul.

Optimization of biogenic synthesis of silver nanoparticles from flavonoid-rich Clinacanthus nutans leaf and stem aqueous extracts

Siti Nur Aishah Mat Yusuf  1   2 , Che Nurul Azieyan Che Mood  2 , Nor Hazwani Ahmad  3 , Doblin Sandai  4 , Chee Keong Lee  5 , Vuanghao Lim  2
Affiliations

Optimization of biogenic synthesis of silver nanoparticles from flavonoid-rich Clinacanthus nutans leaf and stem aqueous extracts

Siti Nur Aishah Mat Yusuf et al. R Soc Open Sci. .

Abstract

Background: Silver nanoparticles (AgNPs) are widely used in food industries, biomedical, dentistry, catalysis, diagnostic biological probes and sensors. The use of plant extract for AgNPs synthesis eliminates the process of maintaining cell culture and the process could be scaled up under a non-aseptic environment. The purpose of this study is to determine the classes of phytochemicals, to biosynthesize and characterize the AgNPs using Clinacanthus nutans leaf and stem extracts. In this study, AgNPs were synthesized from the aqueous extracts of C. nutans leaves and stems through a non-toxic, cost-effective and eco-friendly method. Results: The formation of AgNPs was confirmed by UV-Vis spectroscopy, and the size of AgNP-L (leaf) and AgNP-S (stem) were 114.7 and 129.9 nm, respectively. Transmission electron microscopy (TEM) analysis showed spherical nanoparticles with AgNP-L and AgNP-S ranging from 10 to 300 nm and 10 to 180 nm, with average of 101.18 and 75.38 nm, respectively. The zeta potentials of AgNP-L and AgNP-S were recorded at -42.8 and -43.9 mV. X-ray diffraction analysis matched the face-centred cubic structure of silver and was capped with bioactive compounds. Fourier transform infrared spectrophotometer analysis revealed the presence of few functional groups of phenolic and flavonoid compounds. These functional groups act as reducing agents in AgNPs synthesis. Conclusion: These results showed that the biogenically synthesized nanoparticles reduced silver ions to silver nanoparticles in aqueous condition and the AgNPs formed were stable and less toxic.

Keywords: Clinacanthus nutans; biogenic synthesis; silver nanoparticles; total flavonoid content; total phenolic content.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Figure 1.
Figure 1.
C. nutans leaves and stems.
Figure 2.
Figure 2.
(a) TFC and (b) TPC of CNL and CNS (mean ± s.d., n = 3).
Figure 3.
Figure 3.
Biosynthesis of AgNPs from (a) CNL mixed with AgNO3 solution at 0 h, (b) after 24 h, (c) CNS mixed with AgNO3 solution at 0 h, (d) after 24 h.
Figure 4.
Figure 4.
UV-Vis spectra of (a) AgNP-L and (b) AgNP-S as a function of time. Reaction of 5% C. nutans extract in 1 mM AgNO3 at 25°C.
Figure 5.
Figure 5.
UV–Vis spectra of (a) AgNP-L and (b) AgNP-S for different concentrations of C. nutans extract.
Figure 6.
Figure 6.
UV–Vis spectrum of (a) AgNP-L and (b) AgNP-S at different concentrations of AgNO3.
Figure 7.
Figure 7.
UV–Vis spectra of (a) AgNP-L and (b) AgNP-S at different temperatures.
Figure 8.
Figure 8.
TEM images of (a) AgNP-L, (b) AgNP-S with magnifications of 63 000 × and size distribution of (c) AgNP-L and (d) AgNP-S.
Figure 9.
Figure 9.
SEM images of (a) AgNP-L, (b) AgNP-S with magnifications of 100 000 × and EDX spectra of (c) AgNP-L, (d) AgNP-S.
Figure 10.
Figure 10.
XRD spectra of AgNP-L and AgNP-S.
Figure 11.
Figure 11.
FTIR spectra of (a) CNL, (b) AgNP-L, (c) CNS and (d) AgNP-S.
See this image and copyright information in PMC

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