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Microstructural, spectroscopic, and antibacterial properties of silver-based hybrid nanostructures biosynthesized using extracts of coriander leaves and seeds

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ABSTRACT

Coriander leaves and seeds have been highly appreciated since ancient times, not only due to their pleasant flavors but also due to their inhibitory activity on food degradation and their beneficial properties for health, both ascribed to their strong antioxidant activity. Recently, it has been shown that coriander leaf extracts can mediate the synthesis of metallic nanoparticles through oxidation/reduction reactions. In the present study, extracts of coriander leaves and seeds have been used as reaction media for the wet chemical synthesis of ultrafine silver nanoparticles and nanoparticle clusters, with urchin- and tree-like shapes, coated by biomolecules (mainly, proteins and polyphenols). In this greener route of nanostructure preparation, the active biocompounds of coriander simultaneously play the roles of reducing and stabilizing agents. The morphological and microstructural studies of the resulting biosynthesized silver nanostructures revealed that the nanostructures prepared with a small concentration of the precursor Ag salt (AgNO3 =5 mM) exhibit an ultrafine size and a narrow size distribution, whereas particles synthesized with high concentrations of the precursor Ag salt (AgNO3 =0.5 M) are polydisperse and formation of supramolecular structures occurs. Fourier transform infrared and Raman spectroscopy studies indicated that the bioreduction of the Ag− ions takes place through their interactions with free amines, carboxylate ions, and hydroxyl groups. As a consequence of such interactions, residues of proteins and polyphenols cap the biosynthesized Ag nanoparticles providing them a hybrid core/shell structure. In addition, these biosynthesized Ag nanomaterials exhibited size-dependent plasmon extinction bands and enhanced bactericidal activities against both Gram-positive and Gram-negative bacteria, displaying minimal inhibitory Ag concentrations lower than typical values reported in the literature for Ag nanoparticles, probably due to the synergy of the bactericidal activities of the Ag nanoparticle cores and their capping ligands.

No MeSH data available.


UV-visible spectra of the coriander extracts and biosynthesized Ag samples.Abbreviations: UV, ultraviolet; Cor, coriander; Ag, silver; L-0.5M, final colloid obtained using coriander leaf extract and 0.5 M AgNO3; S-0.5M, sample obtained using extracts of coriander seeds and 0.5 M AgNO3 solution; L-5mM, final colloid obtained using coriander leaf extract and 5 M AgNO3; S-5mM, sample obtained using extracts of coriander seeds and 5 M AgNO3 solution.
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f9-ijn-11-4787: UV-visible spectra of the coriander extracts and biosynthesized Ag samples.Abbreviations: UV, ultraviolet; Cor, coriander; Ag, silver; L-0.5M, final colloid obtained using coriander leaf extract and 0.5 M AgNO3; S-0.5M, sample obtained using extracts of coriander seeds and 0.5 M AgNO3 solution; L-5mM, final colloid obtained using coriander leaf extract and 5 M AgNO3; S-5mM, sample obtained using extracts of coriander seeds and 5 M AgNO3 solution.

Mentions: Figure 9 shows the UV-visible spectra of the Ag samples and the two extracts. These spectra disclose that the bio-synthesized colloids exhibit extinction peaks that are not observed in the spectra of the initial coriander extracts and that they are originated by the surface plasmon absorption of very fine Ag particles. Samples obtained with higher concentrations of AgNO3, L-0.5M and S-0.5M, exhibited broader extinction bands at larger wavelengths (at 470 and 458 nm) in comparison to samples obtained with lower concentrations of AgNO3, L-5mM and S-5mM, the plasmon extinction bands of which were centered at 440 and 437 nm, respectively.


Microstructural, spectroscopic, and antibacterial properties of silver-based hybrid nanostructures biosynthesized using extracts of coriander leaves and seeds
UV-visible spectra of the coriander extracts and biosynthesized Ag samples.Abbreviations: UV, ultraviolet; Cor, coriander; Ag, silver; L-0.5M, final colloid obtained using coriander leaf extract and 0.5 M AgNO3; S-0.5M, sample obtained using extracts of coriander seeds and 0.5 M AgNO3 solution; L-5mM, final colloid obtained using coriander leaf extract and 5 M AgNO3; S-5mM, sample obtained using extracts of coriander seeds and 5 M AgNO3 solution.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036574&req=5

f9-ijn-11-4787: UV-visible spectra of the coriander extracts and biosynthesized Ag samples.Abbreviations: UV, ultraviolet; Cor, coriander; Ag, silver; L-0.5M, final colloid obtained using coriander leaf extract and 0.5 M AgNO3; S-0.5M, sample obtained using extracts of coriander seeds and 0.5 M AgNO3 solution; L-5mM, final colloid obtained using coriander leaf extract and 5 M AgNO3; S-5mM, sample obtained using extracts of coriander seeds and 5 M AgNO3 solution.
Mentions: Figure 9 shows the UV-visible spectra of the Ag samples and the two extracts. These spectra disclose that the bio-synthesized colloids exhibit extinction peaks that are not observed in the spectra of the initial coriander extracts and that they are originated by the surface plasmon absorption of very fine Ag particles. Samples obtained with higher concentrations of AgNO3, L-0.5M and S-0.5M, exhibited broader extinction bands at larger wavelengths (at 470 and 458 nm) in comparison to samples obtained with lower concentrations of AgNO3, L-5mM and S-5mM, the plasmon extinction bands of which were centered at 440 and 437 nm, respectively.

View Article: PubMed Central - PubMed

ABSTRACT

Coriander leaves and seeds have been highly appreciated since ancient times, not only due to their pleasant flavors but also due to their inhibitory activity on food degradation and their beneficial properties for health, both ascribed to their strong antioxidant activity. Recently, it has been shown that coriander leaf extracts can mediate the synthesis of metallic nanoparticles through oxidation/reduction reactions. In the present study, extracts of coriander leaves and seeds have been used as reaction media for the wet chemical synthesis of ultrafine silver nanoparticles and nanoparticle clusters, with urchin- and tree-like shapes, coated by biomolecules (mainly, proteins and polyphenols). In this greener route of nanostructure preparation, the active biocompounds of coriander simultaneously play the roles of reducing and stabilizing agents. The morphological and microstructural studies of the resulting biosynthesized silver nanostructures revealed that the nanostructures prepared with a small concentration of the precursor Ag salt (AgNO3 =5 mM) exhibit an ultrafine size and a narrow size distribution, whereas particles synthesized with high concentrations of the precursor Ag salt (AgNO3 =0.5 M) are polydisperse and formation of supramolecular structures occurs. Fourier transform infrared and Raman spectroscopy studies indicated that the bioreduction of the Ag− ions takes place through their interactions with free amines, carboxylate ions, and hydroxyl groups. As a consequence of such interactions, residues of proteins and polyphenols cap the biosynthesized Ag nanoparticles providing them a hybrid core/shell structure. In addition, these biosynthesized Ag nanomaterials exhibited size-dependent plasmon extinction bands and enhanced bactericidal activities against both Gram-positive and Gram-negative bacteria, displaying minimal inhibitory Ag concentrations lower than typical values reported in the literature for Ag nanoparticles, probably due to the synergy of the bactericidal activities of the Ag nanoparticle cores and their capping ligands.

No MeSH data available.