Scientists have synthesized silver nanoparticles with antibiotic properties using a watery extract of the tree oyster mushroom Pleurotus ostreatus1.

The nanoparticles could potentially be used to coat surgical instruments and in wound-healing creams and gels.

The tree oyster mushroom is an edible fungus shown to have anticancer, antiviral, anti-inflammatory and cholesterol-lowering properties. Previous studies have used it to make silver nanoparticles, but the mushroom's fruiting body has not yet been used to prepare silver nanoparticles.

In search of a green method, scientists from the Karpagam University, India along with colleagues from University of Baghdad, Iraq and University of Malaya, Malaysia added aqueous extract of the mushroom collected from Iraq to a silver nitrate solution, which darkened from pale to dark yellow, indicating the formation of the silver nanoparticles.

A sophisticated imaging technique revealed the formation of well-dispersed spherical nanoparticles, with average size ranging from 10 to 40 nm.

These anti-microbials inhibited the growth of five different bacterial strains — Bacillus subtilis , Bacillus cereus, Staphylococcusaureus, Escherichia coli and Pseudomonas aeruginosa . The antibacterial effects depended on the size and dosage of the nanoparticles.

Since commercial antibiotics can have toxic side-effects on the liver, kidneys and nerve cells, the nanoparticles could offer an alternative method for treating bacterial infections.