Research Highlight

Microbe killing nanoparticles

doi:10.1038/nindia.2014.80 Published online 16 June 2014

Researchers have developed an ecofriendly way of making silver nanoparticles with antibacterial and antifungal properties1. Their method involves reacting guava leaf extract with silver nitrate solution. The nanoparticles could potentially be used to combat human infections caused by fungi and bacteria.

Pathogenic bacteria and fungi are increasingly developing resistance to conventional antimicrobial agents. Researchers have been searching for alternative therapies, one of which involves developing nanoparticles with antimicrobial properties. However, synthesizing such nanoparticles requires using complex processes and toxic chemicals.

Now, the researches have developed a single-step green method for making silver nanoparticles with antimicrobial properties that employs the ecofriendly chemicals guava leaf extract and silver nitrate solution. They tested the antimicrobial properties of the nanoparticles by exposing them to two disease-causing bacteria — Staphylococcus aureus and Escherichia coli — and a pathogenic fungus Candida albicans.

The researchers found that the nanoparticles inhibited the growth of the microbes by preventing the formation of biofilms usually made by these pathogens. The antimicrobial activity of the nanoparticles stemmed from biomolecules derived from guava leaf extract, they say.

The nanoparticles were stable and spherical with a mean diameter of 60 nm making them effective candidates as antimicrobial agents.


1. Gupta, K. et al. One step green synthesis and anti-microbial and anti-biofilm properties of Psidium guajava L. leaf extract-mediated silver nanoparticles. Mater. Lett. 125, 67–70 (2014) doi: 10.1016/j.matlet.2014.03.134