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

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.


Raman spectra of (A) coriander leaf extract and sample L-0.5M and (B) coriander seed extract and sample S-0.5M.Note: Numbers indicate the position of vibrational bands.Abbreviations: 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.
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f8-ijn-11-4787: Raman spectra of (A) coriander leaf extract and sample L-0.5M and (B) coriander seed extract and sample S-0.5M.Note: Numbers indicate the position of vibrational bands.Abbreviations: 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.

Mentions: Figure 8A and B shows the Raman spectra of the coriander extracts and samples L-0.5M and S-0.5M. In both spectra of the biosynthesized samples, two very pronounced bands at around 1,350 and 1,585 cm−1 are observed. They can be associated to symmetric and asymmetric C=O stretching vibrations of the COO− ions,31,32 respectively, and/or phenyl ring stretch.32,33 The high intensity of these bands clearly confirms that the Ag nanoparticle surface and carboxylate ions and/or phenyl groups are directly bound, the Raman signals of which are amplified by the SERS effect.19 In addition, the appearance of a band at around 235 cm−1, which has been associated with the stretching vibrations of Ag–N31,32,34 and Ag–O32,33 vibrations, confirms the formation of bonds between Ag nanoparticle surface and the nitrogen atom of amine groups34 and the oxygen of carboxylate ions32 and/or hydroxyl ions.


Microstructural, spectroscopic, and antibacterial properties of silver-based hybrid nanostructures biosynthesized using extracts of coriander leaves and seeds
Raman spectra of (A) coriander leaf extract and sample L-0.5M and (B) coriander seed extract and sample S-0.5M.Note: Numbers indicate the position of vibrational bands.Abbreviations: 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.
© Copyright Policy
Related In: Results  -  Collection

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

f8-ijn-11-4787: Raman spectra of (A) coriander leaf extract and sample L-0.5M and (B) coriander seed extract and sample S-0.5M.Note: Numbers indicate the position of vibrational bands.Abbreviations: 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.
Mentions: Figure 8A and B shows the Raman spectra of the coriander extracts and samples L-0.5M and S-0.5M. In both spectra of the biosynthesized samples, two very pronounced bands at around 1,350 and 1,585 cm−1 are observed. They can be associated to symmetric and asymmetric C=O stretching vibrations of the COO− ions,31,32 respectively, and/or phenyl ring stretch.32,33 The high intensity of these bands clearly confirms that the Ag nanoparticle surface and carboxylate ions and/or phenyl groups are directly bound, the Raman signals of which are amplified by the SERS effect.19 In addition, the appearance of a band at around 235 cm−1, which has been associated with the stretching vibrations of Ag–N31,32,34 and Ag–O32,33 vibrations, confirms the formation of bonds between Ag nanoparticle surface and the nitrogen atom of amine groups34 and the oxygen of carboxylate ions32 and/or hydroxyl ions.

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.