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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.


Fourier transform infrared (FTIR) 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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f7-ijn-11-4787: Fourier transform infrared (FTIR) 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: FTIR and Raman spectroscopic studies were carried out to identify the functional groups responsible for the bioreduction of Ag+ ions and the stabilizing action of Ag nanoparticles. Figure 7A presents the FTIR spectra of the coriander leaf extract and sample L-0.5M. In the spectrum of the leaf extract, the broad band observed in the wavenumber range of 3,700–2,500 cm−1 and centered around 3,300 cm−1 can be mainly attributed to N–H and O–H stretching vibrations of coriander proteins and phenols. The peak at 2,961 cm−1 is associated to stretching vibrations of methyl groups, and the absorbance bands observed at 1,603, 1,405, and 1,119 cm−1 can be associated to C=O stretching vibrations (from amide I of proteins), C–OH bending vibrations (from phenols, polysaccharides, and polyols), and –C–O and C–O–H stretching vibrations of alcohols, respectively. Also, the band at 1,119 cm−1 could have contributions from C–N stretching vibrations of amine. The weak peak at 1,268 cm−1 could correspond to the C–H vibration of methyl group and/or C–O stretching band.


Microstructural, spectroscopic, and antibacterial properties of silver-based hybrid nanostructures biosynthesized using extracts of coriander leaves and seeds
Fourier transform infrared (FTIR) 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

f7-ijn-11-4787: Fourier transform infrared (FTIR) 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: FTIR and Raman spectroscopic studies were carried out to identify the functional groups responsible for the bioreduction of Ag+ ions and the stabilizing action of Ag nanoparticles. Figure 7A presents the FTIR spectra of the coriander leaf extract and sample L-0.5M. In the spectrum of the leaf extract, the broad band observed in the wavenumber range of 3,700–2,500 cm−1 and centered around 3,300 cm−1 can be mainly attributed to N–H and O–H stretching vibrations of coriander proteins and phenols. The peak at 2,961 cm−1 is associated to stretching vibrations of methyl groups, and the absorbance bands observed at 1,603, 1,405, and 1,119 cm−1 can be associated to C=O stretching vibrations (from amide I of proteins), C–OH bending vibrations (from phenols, polysaccharides, and polyols), and –C–O and C–O–H stretching vibrations of alcohols, respectively. Also, the band at 1,119 cm−1 could have contributions from C–N stretching vibrations of amine. The weak peak at 1,268 cm−1 could correspond to the C–H vibration of methyl group and/or C–O stretching band.

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.