John de Mello tells Soft Matter about his hot communication.

Could you explain the significance of your article to the non-specialist?
Conjugated polyelectrolytes (CPs) are emissive materials that lose their emission completely in the presence of trace quantities of certain molecules. This strong response allows them to be employed as sensitive chemical sensors, and there's growing interest in using them for biological sensing too. Unfortunately, their sensitivity drops dramatically when they're transferred to typical biological environments such as blood and urine due to the high levels of dissolved salts. In this work, we've been able to prevent this loss of sensitivity through the use of carefully selected additives. This will hopefully pave the way to using CPs as powerful sensors for a variety of biological applications.

What has motivated you to conduct this work?
I think it just struck us as an interesting challenge. Previous studies in the literature by Tim Swager and others had demonstrated the remarkable sensitivity of CP-based sensors, and we were curious to see whether they could be successfully adapted to use in high-salt biological environments. We don't come from a conventional biochemical background - this work was a collaborative effort by physical and synthetic chemists - so it was an interesting diversion from our usual research activities.

Where do you see this work developing in the future?
The work described here is very much proof-of-principle research. Our goal at the outset was to demonstrate that CPs could function as effective sensors in high salt conditions - a critical first step in creating a viable biosensor. To do this, we made use of clean buffer solutions rather than complex biological media. The next obvious step is to start using real biological fluids like blood and urine.

Are there any particular challenges facing future research in this area?
Yes, I'm sure their use in blood and urine will throw up all sorts of challenges and difficulties we hadn't anticipated!