Enhanced biosensors are on the horizon thanks to research on ionic liquids by scientists in the US.

Gary Baker and colleagues at Oak Ridge National Laboratory have created biosensors for compounds that are poorly soluble in water. They replaced the water used in detection assays with an ionic liquid. Such assays rely on the interaction of an analyte with its antibody. However many analytes, including several drugs and pesticides, are much more soluble in ionic liquids than water. This makes ionic liquids more suitable for assays for these compounds. 

Baker and his team looked at the effect of an ionic liquid on an antibody's ability to recognise its analyte. They chose a fluorescent molecule, BODIPY FL, as an example. They measured the effects of increasing the amount of ionic liquid in the solvent from changes to the emission spectrum of BODIPY FL. 

Recognition of the analyte by its antibody caused a decrease in fluorescence; the better the interaction, the greater the drop in emission. The researchers found that the antibody was still able to recognise BODIPY FL even when the antibodies were chemically attached to a glass slide and immersed in neat ionic liquid.

According to Baker, ionic liquid solvents may lead to 'biosensors with vastly improved operational lifetimes' because they avoid many of the protein inactivation mechanisms that happen in water.

Robin Rogers, an expert in ionic liquids at the University of Alabama, US, said 'the use of ionic liquids in biosciences is perhaps one of the most exciting and challenging areas in the field today.I expect many new analytical technologies to emerge from such approaches.'   

Rachel Warfield