Research Highlights

New eco-friendly recipe for nanoparticles

doi:10.1038/nindia.2011.42 Published online 28 March 2011

Researchers have devised a new eco-friendly method for synthesizing silver, copper and silver–copper alloy nanoparticles. The researchers used microwave-assisted heating, starch and ascorbic acid to produce their nanoparticles, which demonstrated antibiotic properties.

Nanosized metallic and bimetallic nanoparticles have attracted attention for their optical, electronic, catalytic and antibiotic properties. However, the chemicals needed to produce such nanoparticles are damaging to the environment, and the simultaneous reduction of metals such as silver and copper is difficult to achieve.

To find an eco-friendly way of preparing both metallic and bimetallic nanoparticles, the researchers used a scheme based on microwave-assisted heating, with starch as the stabilizing agent and ascorbic acid as the reducing agent.

The resulting silver, copper and silver–copper alloy nanoparticles measured 30–55 nm in diameter. The starch-stabilized aqueous solution of metallic and bimetallic nanoparticles exhibited interesting antibacterial activity when exposed to strains of E. coli and S. aureus, even at concentrations as low as 0.3 mg l–1. The nanoparticles were more effective against E. coli than S. aureus.

Silver and copper ions released by the nanoparticles can attach to and rupture the negatively charged bacterial cell wall, leading to protein denaturation and cell death. The researchers say that this eco-friendly method of producing nanoparticles can also be extended to other noble metals.


  1. Valodkar, M. et al. Synthesis and anti-bacterial activity of Cu, Ag and Cu–Ag alloy nanoparticles: a green approach. Mater. Res. Bull. 46, 384-389 (2011) | Article |