Not everyone is quite as enthusiastic as whoever wrote this press release about silver nanoparticles (due to potential environmental issues as more manufactured silver nanoparticles enter the ecosystem). Still, it’s good news that there may be a greener way to synthesize them. A July 20, 2016 news item on Azonano ‘spills the beans’,

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… researchers from the Guru Nanak National College, the Institute of Microbial Technology, Mata Gujri College and Punjab University, have found a simple, non-toxic and environmentally friendly way to synthesize AgNPs [silver nanoparticles] using seed extract of Vigna radiata, commonly known as the mung bean or green gram.

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Manoj Kumar Choudhary and colleagues used aqueous seed extract of mung beans to break up aqueous silver nitrate solution into NPs, as well as to reduce and stabilize the particles. The NPs were characterized by UV–visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, atomic absorption spectroscopy and X-ray diffraction. They were then tested for antimicrobial effectiveness.

As reported in Applied Nanoscience, the researchers found that phytochemicals present in the seed extract were effective at reducing and stabilizing the Ag metal ions. They found they could synthesize crystalline, spherically-shaped NPs, with a size range of 5 to 30 nm. The particles remained highly stable for months at room temperature, even after five months.

Antibacterial activity was assayed by the standard well-diffusion method, which showed that the biogenic silver NPs had broad-spectrum antibacterial activity against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus.

“In the present paper, we report a simple, eco-friendly and cost-effective synthesis method of AgNPs at ambient conditions using seed extract of Vigna radiata as a reducing and stabilizing agent,” say Choudhary and team. “The AgNPs synthesized by this method have efficient antimicrobial activity against pathogenic bacteria.”

The researchers say the next step would be further investigation of the potential applications of the synthesized AgNPs, as the outcome of the study could be useful for applications in nanotechnology-based applications in pharmacology and medicine.

Here’s a link to and a citation for the paper,

A facile biomimetic preparation of highly stabilized silver nanoparticles derived from seed extract of Vigna radiata and evaluation of their antibacterial activity by Manoj Kumar Choudhary, Jyoti Kataria, Swaranjit Singh Cameotra, Jagdish Singh. Appl Nanosci (2016) 6: 105. doi:10.1007/s13204-015-0418-6 First Online: 19 February 2015

This paper is open access.