Abstract
In recent years’ synthesis of metal nanoparticle using plants has been extensively studied and recognized as a non-toxic and efficient method applicable in biomedical field. The aim of this study is to investigate the role of different parts of medical plant Carduus crispus on synthesizing silver nanoparticles and characterize the produced nanoparticle. Our study showed that silver nanoparticles (AgNP) synthesized via whole plant extract exhibited a blue shift in absorption spectra with increased optical density, which correlates to a high yield and small size. Also, the results of zeta potential, X-ray diffraction, photon cross-correlation spectroscopy analysis showed the surface charge of − 54.29 ± 4.96 mV (AgNP-S), − 42.64 ± 3.762 mV (AgNP-F), − 46.02 ± 4.17 mV (AgNP-W), the crystallite size of 36 nm (AgNP-S), 13 nm (AgNP-F), 14 nm (AgNP-W) with face-centered cubic structure and average grain sizes of 145.1 nm, 22.5 nm and 99.6 nm. Another important characteristic, such as elemental composition and constituent capping agent has been determined by energy-dispersive X-ray spectroscopy and Fourier transform infrared. The silver nanoparticles were composed of ~ 80% Ag, ~ 15% K, and ~ 7.5% Ca (or ~ 2.8% P) elements. Moreover, the results of the FTIR measurement suggested that the distinct functional groups present in both AgNP-S and AgNP-F were found in AgNP-W. The atomic force microscopy analysis revealed that AgNP-S, AgNP-F and AgNP-W had sizes of 131 nm, 33 nm and 70 nm respectively. In addition, the biosynthesized silver nanoparticles were evaluated for their cytotoxicity and antibacterial activity. At 17 µg/ml concentration, AgNP-S, AgNP-F and AgNP-W showed very low toxicity on HepG2 cell line but also high antibacterial activity. The silver nanoparticles showed antibacterial activity on both gram-negative bacterium Escherichia coli (5.5 ± 0.2 mm to 6.5 ± 0.3 mm) and gram-positive bacterium Micrococcus luteus (7 ± 0.4 mm to 7.7 ± 0.5 mm). Our study is meaningful as a first observation indicating the possibility of using special plant organs to control the characteristics of nanoparticles.
Highlights
In recent years’ synthesis of metal nanoparticle using plants has been extensively studied and recognized as a non-toxic and efficient method applicable in biomedical field
The change in color of biosynthesized AgNP is due to the excitation of surface plasmon resonance (SPR)
The difference in color change rate might be due to the different properties of the plant, the medicinal plant contains a wide range of phytochemicals, such as flavonoids, polyphenols, terpenoids, etc.[44] that assist in the formation of silver nanoparticles
Summary
In recent years’ synthesis of metal nanoparticle using plants has been extensively studied and recognized as a non-toxic and efficient method applicable in biomedical field. Plants contain a wide range of metabolites that can aid in reducing silver ion, stabilizing and capping AgNP13, the concentration and composition of AgNP will vary depending on the plant type[3] This is especially the case for the medicinal plant as it is a rich source of complex phytochemicals and antioxidants. The appearance of pores on membrane result to diffusion of nanoparticles into the cell where it binds with sulfur and phosphorus-containing proteins, leading to the inactivation of proteins and D NA17 Another hypothesis suggests that the antibacterial activity of AgNPs results from the release of A g+ ions through the oxidation dissolution process. The present study aimed to synthesize silver nanoparticles with medicinal plant Carduus crispus extracts and characterize the final product, and evaluate their antibacterial activities
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