Very Green Photosynthesis of Gold Nanoparticles by a Living Aquatic Plant: Photoreduction of AuIII by the Seaweed Ulva armoricana

Ofhani C Mukhoro; Wiets D Roos; Mohammed Jaffer; John J Bolton; Martin J Stillman; Denzil R Beukes; Edith Antunes

doi:10.1002/chem.201704448

Very Green Photosynthesis of Gold Nanoparticles by a Living Aquatic Plant: Photoreduction of Au^III by the Seaweed Ulva armoricana

Chemistry. 2018 Feb 1;24(7):1657-1666. doi: 10.1002/chem.201704448. Epub 2017 Dec 27.

Authors

Ofhani C Mukhoro¹, Wiets D Roos², Mohammed Jaffer³, John J Bolton⁴, Martin J Stillman⁵, Denzil R Beukes⁶, Edith Antunes⁷

Affiliations

¹ Department of Biotechnology, University of the Western Cape, Bellville, 7535, South Africa.
² Department of Physics, University of the Free State, Bloemfontein, 9300, South Africa.
³ Electron Microscopy Unit, University of Cape Town, Rondebosch, 7701, South Africa.
⁴ Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa.
⁵ Department of Chemistry, University of Western Ontario, Ontario, Canada.
⁶ School of Pharmacy, University of the Western Cape, Bellville, 7535, South Africa.
⁷ Department of Chemistry, University of the Western Cape, Bellville, 7535, South Africa.

PMID: 29164714
DOI: 10.1002/chem.201704448

Abstract

Light-assisted in vivo synthesis of gold nanoparticles (NPs) from aqueous solutions of dilute Au^III salts by a living green marine seaweed (Ulva armoricana) is reported for the first time. NPs synthesised using typical procedures have many associated environmental hazards. The reported methods involve green, nontoxic, eco-friendly synthetic procedures. The formation of AuNPs was extremely rapid (≈15 min) following illumination of the living U. armoricana, while the rate of NP formation in the dark was very slow (over 2 weeks). The properties of the AuNPs formed were confirmed using a battery of spectroscopic techniques. U. armoricana were found to be very efficient in Au⁰ uptake, and this, together with the rapid formation of AuNPs under illumination, indicated that the seaweed remained living during NP formation. The TEM images supported this, revealing that the thylakoid membranes and cell structure remained intact. The AuNPs formed on the surface of U. armoricana thallus, along the cell walls and in the chloroplasts. Without further workup, the dried, U. armoricana-supported AuNPs were efficient in the catalytic reduction of 4-nitrophenol, demonstrating the completely green cycle of AuNP formation and catalytic activity. The results mean that an aquatic plant growing in water rich in gold salts could bio-accumulate AuNPs from its aquatic environment, simply with the activation of sunlight.

Keywords: catalysis; gold; green nanotechnology; nanoparticles; photosynthesis.

MeSH terms

Catalysis
Gold / chemistry*
Green Chemistry Technology / methods
Kinetics
Light
Metal Nanoparticles / chemistry*
Nitrophenols / chemistry
Oxidation-Reduction
Particle Size
Photosynthesis
Seaweed / chemistry*
Surface Properties
Ulva / chemistry*

Substances

Nitrophenols
Gold
4-nitrophenol