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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.


Related in: MedlinePlus

Photographs of the Staphylococcus aureus bacteria grown on agar plates.Notes: (A) control experiment, (B) in the presence of the extract of coriander leaves, (C) in the presence of the extract of coriander seeds, (D) in the presence of sample L-0.5M, and (E) in the presence of sample S-0.5M.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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f10-ijn-11-4787: Photographs of the Staphylococcus aureus bacteria grown on agar plates.Notes: (A) control experiment, (B) in the presence of the extract of coriander leaves, (C) in the presence of the extract of coriander seeds, (D) in the presence of sample L-0.5M, and (E) in the presence of sample S-0.5M.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: The biological assays showed that the biosynthesized silver samples displayed a significant antibacterial effect against Gram-negative (S. typhimurium) and Gram-positive (S. aureus) bacteria, whereas the coriander extracts exhibited a weak antibacterial activity. Figures 10 and 11 depict photographs of the bacteria grown on agar plates in the presence and absence of 20 μL of the coriander extracts or 20 μL of aqueous colloidal suspensions of the biosynthesized nanoparticles at a concentration of 10 mg⋅mL−1. Interestingly, for both bacteria, the agar plates incubated in the presence of coriander leaf extract exhibited regions in which the bacterial growth was clearly inhibited (Figures 10B and 11B) in comparison with the control experiment (Figures 10A and 11A), whereas this effect was much less marked for agar plates incubated in the presence of coriander seed extract (Figures 10C and 11C). However, clear nongrowth halos were observed in the agar plates for both bacteria when incubated in the presence of biosynthesized silver samples.


Microstructural, spectroscopic, and antibacterial properties of silver-based hybrid nanostructures biosynthesized using extracts of coriander leaves and seeds
Photographs of the Staphylococcus aureus bacteria grown on agar plates.Notes: (A) control experiment, (B) in the presence of the extract of coriander leaves, (C) in the presence of the extract of coriander seeds, (D) in the presence of sample L-0.5M, and (E) in the presence of sample S-0.5M.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

f10-ijn-11-4787: Photographs of the Staphylococcus aureus bacteria grown on agar plates.Notes: (A) control experiment, (B) in the presence of the extract of coriander leaves, (C) in the presence of the extract of coriander seeds, (D) in the presence of sample L-0.5M, and (E) in the presence of sample S-0.5M.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: The biological assays showed that the biosynthesized silver samples displayed a significant antibacterial effect against Gram-negative (S. typhimurium) and Gram-positive (S. aureus) bacteria, whereas the coriander extracts exhibited a weak antibacterial activity. Figures 10 and 11 depict photographs of the bacteria grown on agar plates in the presence and absence of 20 μL of the coriander extracts or 20 μL of aqueous colloidal suspensions of the biosynthesized nanoparticles at a concentration of 10 mg⋅mL−1. Interestingly, for both bacteria, the agar plates incubated in the presence of coriander leaf extract exhibited regions in which the bacterial growth was clearly inhibited (Figures 10B and 11B) in comparison with the control experiment (Figures 10A and 11A), whereas this effect was much less marked for agar plates incubated in the presence of coriander seed extract (Figures 10C and 11C). However, clear nongrowth halos were observed in the agar plates for both bacteria when incubated in the presence of biosynthesized silver samples.

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.


Related in: MedlinePlus