doi:10.1038/nindia.2016.35 Published online 9 March 2016
Researchers have synthesized a sensitive nanobiosensor that can detect minute traces of histidine-rich protein-2, an antigen that the malaria parasite Plasmodium falciparum secretes into the bloodstream of infected humans1. This biosensor is potentially useful for diagnosing malignant malaria at an early stage.
Malaria still infects millions and kills hundreds of thousands of people every year around the globe. Current techniques for diagnosing malaria are expensive and time-consuming.
To develop a cheap biosensor for detecting the malaria parasite, the researchers deposited copper-doped zinc oxide nanofibres on a glassy carbon electrode. After treating this electrode with mercaptopropionic acid, they put antigen-specific antibodies on its surface.
The scientists monitored the electrode’s electrical impedance spectrum by dipping the electrode in solutions containing different concentrations of the malaria-specific antigen. The impedance, which is the resistance to a current generated by the electrode, changed with antigen concentration.
The biosensor selectively detected an antigen concentration as low as 6 attograms in a millilitre of antigen-containing solution, even in the presence of interfering agents such as various human and animal proteins. The biosensor is reusable: it retained 86% of its original sensitivity after being stored for two months, the researchers say.