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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

Results of the MIC experiments.Notes: Absorbance measured at λ=540 nm of the incubated (A) S. typhimurium bacteria and (B) S. aureus bacteria as a function of the content of silver in the colloids of samples L-0.5M and S-0.5M. The control data were obtained from the incubated bacteria in the absence of nanoparticles.Abbreviations: MIC, minimal inhibitory concentration; S. typhimurium, Salmonella typhimurium; S. aureus, Staphylococcus aureus; 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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f12-ijn-11-4787: Results of the MIC experiments.Notes: Absorbance measured at λ=540 nm of the incubated (A) S. typhimurium bacteria and (B) S. aureus bacteria as a function of the content of silver in the colloids of samples L-0.5M and S-0.5M. The control data were obtained from the incubated bacteria in the absence of nanoparticles.Abbreviations: MIC, minimal inhibitory concentration; S. typhimurium, Salmonella typhimurium; S. aureus, Staphylococcus aureus; 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 MIC experiments showed that the amount of silver required for producing a significant inhibition in the growth of the Gram-positive and Gram-negative bacteria was less than 2 μg⋅mL−1 (Figure 12), concentration lower than the MIC values typically reported in the literature using Ag nanoparticles.35,36 These extreme low values are due probably to the synergy of the bactericidal activities of the biosynthe-sized nanoparticles and their capping ligands which are residues of coriander biomolecules. In this regard, it is important to note that both coriander extracts did not display effects on the bacterial growth at concentrations below 100 μg⋅mL−1.


Microstructural, spectroscopic, and antibacterial properties of silver-based hybrid nanostructures biosynthesized using extracts of coriander leaves and seeds
Results of the MIC experiments.Notes: Absorbance measured at λ=540 nm of the incubated (A) S. typhimurium bacteria and (B) S. aureus bacteria as a function of the content of silver in the colloids of samples L-0.5M and S-0.5M. The control data were obtained from the incubated bacteria in the absence of nanoparticles.Abbreviations: MIC, minimal inhibitory concentration; S. typhimurium, Salmonella typhimurium; S. aureus, Staphylococcus aureus; 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

f12-ijn-11-4787: Results of the MIC experiments.Notes: Absorbance measured at λ=540 nm of the incubated (A) S. typhimurium bacteria and (B) S. aureus bacteria as a function of the content of silver in the colloids of samples L-0.5M and S-0.5M. The control data were obtained from the incubated bacteria in the absence of nanoparticles.Abbreviations: MIC, minimal inhibitory concentration; S. typhimurium, Salmonella typhimurium; S. aureus, Staphylococcus aureus; 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 MIC experiments showed that the amount of silver required for producing a significant inhibition in the growth of the Gram-positive and Gram-negative bacteria was less than 2 μg⋅mL−1 (Figure 12), concentration lower than the MIC values typically reported in the literature using Ag nanoparticles.35,36 These extreme low values are due probably to the synergy of the bactericidal activities of the biosynthe-sized nanoparticles and their capping ligands which are residues of coriander biomolecules. In this regard, it is important to note that both coriander extracts did not display effects on the bacterial growth at concentrations below 100 μg⋅mL−1.

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