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In vivo synthesis of nanomaterials in plants: location of silver nanoparticles and plant metabolism

Luca Marchiol1*, Alessandro Mattiello1, Filip Pošćić1, Cristiana Giordano2 and Rita Musetti1

Author Affiliations

1 Department of Agriculture and Environmental Sciences, University of Udine, via delle Scienze 206, Udine 33100, Italy

2 Centro di Microscopie Elettroniche “Laura Bonzi”, ICCOM, CNR, Via Madonna del Piano 10, Sesto Fiorentino, Firenze 50019, Italy

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Nanoscale Research Letters 2014, 9:101  doi:10.1186/1556-276X-9-101

Published: 2 March 2014


Metallic nanoparticles (MeNPs) can be formed in living plants by reduction of the metal ions absorbed as soluble salts. It is very likely that plant metabolism has an important role in MeNP biosynthesis. The in vivo formation of silver nanoparticles (AgNPs) was observed in Brassica juncea, Festuca rubra and Medicago sativa. Plants were grown in Hoagland's solution for 30 days and then exposed for 24 h to a solution of 1,000 ppm AgNO3. In the leaf extracts of control plants, the concentrations of glucose, fructose, ascorbic acid, citric acid and total polyphenols were determined. Total Ag content in plant fractions was determined by inductively coupled plasma atomic emission spectroscopy. Despite the short exposure time, the Ag uptake and translocation to plant leaves was very high, reaching 6,156 and 2,459 mg kg−1 in B. juncea and F. rubra, respectively. Ultrastructural analysis was performed by transmission electron microscopy (TEM), and AgNPs were detected by TEM X-ray microanalysis. TEM images of plant fractions showed the in vivo formation of AgNPs in the roots, stems and leaves of the plants. In the roots, AgNPs were present in the cortical parenchymal cells, on the cell wall of the xylem vessels and in regions corresponding to the pits. In leaf tissues, AgNPs of different sizes and shapes were located close to the cell wall, as well as in the cytoplasm and within chloroplasts. AgNPs were not observed in the phloem of the three plant species. This is the first report of AgNP synthesis in living plants of F. rubra. The contents of reducing sugars and antioxidant compounds, proposed as being involved in the biosynthesis of AgNPs, were quite different between the species, thus suggesting that it is unlikely that a single substance is responsible for this process.

MSC 2010

92 Biology and other natural sciences; 92Cxx Physiological, cellular and medical topics; 92C80 Plant biology

Festuca rubra; Medicago sativa; Brassica juncea; Silver; Nanoparticles; Biosynthesis; Plant metabolites