Portable FRET sensing of proteins, hormones, and toxins using DNA aptamers and quantum dots

There is an urgent need to develop methods and devices that make the monitoring of any compound of interest in the public water system more reliable, more sensitive and more economical. We are developing a platform sensing chemistry based on rapidly responsive fluorescent resonance energy transfer, or FRET with DNA aptamers as molecular recognition elements. In particular, we are using highly stable, highly fluorescent quantum dots and have implemented the sensing chemistry in a format compatible with readout by an inexpensive, portable, and yet highly sensitive fluorometer. Using different aptamers in the sensor formulation, we demonstrate the sensing and quantitation of the protein insulin and the small molecule hormone, thyroxine (T4). We are presently formulating similar sensors for the potent cyanobacterial toxin, anatoxin-a. Building on extensive previous glucose sensing experience, we also look towards the necessary modifications to develop a fully reversible, on-line sensor for similar analytes.