doi:10.1038/nindia.2014.53 Published online 21 April 2014
Researchers have made rod-shaped lead selenide quantum dots using a marine fungus. These semiconducting dots could be used to harness solar energy .
Lead selenide quantum dots have a large bandgap — the energy gap that determines the electrical conductivity of semiconducting materials. Present techniques for producing such quantum dots are expensive and involve toxic chemicals. Various microorganisms have been used to synthesize quantum dots, rods and wires for medical and biological imaging applications, but to date no cost-effective green method for synthesizing lead selenide quantum dots has been found.
The researchers devised an ecofriendly technique for making lead selenide quantum dots that involves using a lead- and selenium-tolerant marine fungus (Aspergillus terreus), together with lead and selenium.
The marine fungus produced lead selenide quantum dots as nanorods with an average diameter of 59 nm. Absorption studies using ultraviolet and visible light revealed that the nanorods were capped by proteins from the marine fungus. This protein coat enhanced the nanorods' stability and biocompatibility, preventing their aggregation.
The study also found the nanorods had a much higher bandgap than bulk lead selenide. In addition, the nanorods were found to fluoresce. This combination of a large bandgap and fluorescence makes the nanorods very promising for use in solar cells, biosensing and bioimaging.