Research Highlight

Sensor for detecting anthrax toxin

doi:10.1038/nindia.2015.105 Published online 18 August 2015

Researchers have developed a sensitive sensor that can detect minute traces of anthrax protective antigen, a toxin secreted by the bacterium Bacillus anthrax1. This sensor will be potentially useful for detecting this bacterium in animals and humans.

The bacterium is a potential agent for germ warfare. It infects and kills animals and humans by secreting exotoxins such as protective antigen, lethal factor and edema factor. Of these exotoxins, protective antigen in conjunction with lethal factor is the deadliest.

To devise a sensitive and rapid technique for detecting protective antigen, the researchers fabricated the sensor. It had a sensing platform, consisting of bismuth nanoparticles and a glassy carbon electrode modified with multiwalled carbon nanotubes, and a signal amplifying tag containing a conjugate of titanium phosphate nanoparticles, cadmium ions and mouse antibodies specific to protective antigen.

The researchers probed the efficacy of the sensor for detecting protective antigen in spiked human serum samples. They found that the current increased with increasing protective antigen concentration in the serum samples. The sensor could detect the toxin down to a concentration of 50 picograms per millilitre.

In addition, the sensor could perform analysis within 35 minutes and retained 93% of its original signal-generating efficiency after being stored for 40 days, suggesting its potential for rapidly detecting the anthrax pathogen.


1. Sharma, M. K. et al. Electrochemical immunosensor based on bismuth nanocomposite film and cadmium ions functionalized titanium phosphates for the detection of anthrax protective antigen toxin. Biosens. Bioelectron. 74, 299–304 (2015)