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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.

No MeSH data available.


Dark field images of onion layers after incubation with HAuCl4 solution, using a similar protocol as in Fig. 2. The magnification is a) 10×, b) 20× and c) 50×, respectively. The scattering of yellow light originating from gold nanoparticles appears without any correlation to the cellular structure of the onion layer.
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Figure 3: Dark field images of onion layers after incubation with HAuCl4 solution, using a similar protocol as in Fig. 2. The magnification is a) 10×, b) 20× and c) 50×, respectively. The scattering of yellow light originating from gold nanoparticles appears without any correlation to the cellular structure of the onion layer.

Mentions: For comparison, Fig. 3 shows dark field images of onion cell layers after 20 h of incubation with chloroauric acid. The onion samples incubated in chloroauric acid did not show any change of color after drying. In the dark field micrographs, yellow light scattered from small gold nanoparticles shows that these gold structures are formed only at a few points without any correlation to the cellular structure of the epithelial tissue. A templating effect due to the cellular matrix of the onion layer as it has been observed for silver does not exist for the formation of gold nanoparticles.


Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering
Dark field images of onion layers after incubation with HAuCl4 solution, using a similar protocol as in Fig. 2. The magnification is a) 10×, b) 20× and c) 50×, respectively. The scattering of yellow light originating from gold nanoparticles appears without any correlation to the cellular structure of the onion layer.
© Copyright Policy - Beilstein
Related In: Results  -  Collection

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

Figure 3: Dark field images of onion layers after incubation with HAuCl4 solution, using a similar protocol as in Fig. 2. The magnification is a) 10×, b) 20× and c) 50×, respectively. The scattering of yellow light originating from gold nanoparticles appears without any correlation to the cellular structure of the onion layer.
Mentions: For comparison, Fig. 3 shows dark field images of onion cell layers after 20 h of incubation with chloroauric acid. The onion samples incubated in chloroauric acid did not show any change of color after drying. In the dark field micrographs, yellow light scattered from small gold nanoparticles shows that these gold structures are formed only at a few points without any correlation to the cellular structure of the epithelial tissue. A templating effect due to the cellular matrix of the onion layer as it has been observed for silver does not exist for the formation of gold nanoparticles.

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.