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Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering

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ABSTRACT

We report fast and simple green synthesis of plasmonic silver nanoparticles in the epidermal cells of onions after incubation with AgNO3 solution. The biological environment supports the generation of silver nanostructures in two ways. The plant tissue delivers reducing chemicals for the initial formation of small silver clusters and their following conversion to plasmonic particles. Additionally, the natural morphological structures of the onion layers, in particular the extracellular matrix provides a biological template for the growth of plasmonic nanostructures. This is indicated by red glowing images of extracellular spaces in dark field microscopy of onion layers a few hours after AgNO3 exposure due to the formation of silver nanoparticles. Silver nanostructures generated in the extracellular space of onion layers and within the epidermal cell walls can serve as enhancing plasmonic structures for one- and two-photon-excited spectroscopy such as surface enhanced Raman scattering (SERS) and surface enhanced hyper-Raman scattering (SEHRS). Our studies demonstrate a templated green preparation of enhancing plasmonic nanoparticles and suggest a new route to deliver silver nanoparticles as basic building blocks of plasmonic nanosensors to plants by the uptake of solutions of metal salts.

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Image and spectrum of multi-color luminescence collected from onion cell layers after incubation with AgNO3. The excitation wavelength was at 473 nm provided by a laser diode operated at around 5 mW through a 100× oil immersion objective. The illuminated spot is ca. 10 µm2.
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Figure 1: Image and spectrum of multi-color luminescence collected from onion cell layers after incubation with AgNO3. The excitation wavelength was at 473 nm provided by a laser diode operated at around 5 mW through a 100× oil immersion objective. The illuminated spot is ca. 10 µm2.

Mentions: Among various plant materials applied for green synthesis of metal nanoparticles, also the use of onion extract for the preparation of gold and silver nanoparticles has been reported [24–25]. In all those studies, onions have been crushed and boiled and finally, onion extract has been employed in the preparation process. Here, we explore the in situ preparation of metal nanoparticles in intact fresh onion cell layers at room temperature. After about 20 h of exposure to AgNO3 solution, and a following drying period of 2–3 h, the onion samples appear in a reddish color, compared to their initial whitish color, suggesting the formation of nanoparticles. Additionally, Fig. 1 shows a strong luminescence signal in yellow-greenish colors emitted from the onion layers upon excitation at 473 nm.


Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering
Image and spectrum of multi-color luminescence collected from onion cell layers after incubation with AgNO3. The excitation wavelength was at 473 nm provided by a laser diode operated at around 5 mW through a 100× oil immersion objective. The illuminated spot is ca. 10 µm2.
© Copyright Policy - Beilstein
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4979762&req=5

Figure 1: Image and spectrum of multi-color luminescence collected from onion cell layers after incubation with AgNO3. The excitation wavelength was at 473 nm provided by a laser diode operated at around 5 mW through a 100× oil immersion objective. The illuminated spot is ca. 10 µm2.
Mentions: Among various plant materials applied for green synthesis of metal nanoparticles, also the use of onion extract for the preparation of gold and silver nanoparticles has been reported [24–25]. In all those studies, onions have been crushed and boiled and finally, onion extract has been employed in the preparation process. Here, we explore the in situ preparation of metal nanoparticles in intact fresh onion cell layers at room temperature. After about 20 h of exposure to AgNO3 solution, and a following drying period of 2–3 h, the onion samples appear in a reddish color, compared to their initial whitish color, suggesting the formation of nanoparticles. Additionally, Fig. 1 shows a strong luminescence signal in yellow-greenish colors emitted from the onion layers upon excitation at 473 nm.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

We report fast and simple green synthesis of plasmonic silver nanoparticles in the epidermal cells of onions after incubation with AgNO3 solution. The biological environment supports the generation of silver nanostructures in two ways. The plant tissue delivers reducing chemicals for the initial formation of small silver clusters and their following conversion to plasmonic particles. Additionally, the natural morphological structures of the onion layers, in particular the extracellular matrix provides a biological template for the growth of plasmonic nanostructures. This is indicated by red glowing images of extracellular spaces in dark field microscopy of onion layers a few hours after AgNO3 exposure due to the formation of silver nanoparticles. Silver nanostructures generated in the extracellular space of onion layers and within the epidermal cell walls can serve as enhancing plasmonic structures for one- and two-photon-excited spectroscopy such as surface enhanced Raman scattering (SERS) and surface enhanced hyper-Raman scattering (SEHRS). Our studies demonstrate a templated green preparation of enhancing plasmonic nanoparticles and suggest a new route to deliver silver nanoparticles as basic building blocks of plasmonic nanosensors to plants by the uptake of solutions of metal salts.

No MeSH data available.


Related in: MedlinePlus