Angew.Chem.Int.Ed.http://doi.org/c5ddsw(2012)

Credit: © 2012 WILEY

The ability to detect trace quantities of chemical entities is important in a wide variety of applications ranging from environmental monitoring to medical diagnostics. One approach to chemical sensing is to use sensor arrays that are capable of detecting — and distinguishing between — multiple analytes. Now, Pavel Anzenbacher Jr and co-workers from Bowling Green State University in Ohio have made porous mats from polymer nanofibres that are able to identify metal cations in a qualitative and quantitative manner.

Anzenbacher and colleagues overlapped roughly perpendicular polymer nanofibres and formed junctions between them by exposing them to heat or a solvent. In these 'attoreactor' junctions, an oligoamine embedded in one nanofibre reacts with a fluorophore precursor impregnated in the other to form fluorescent probe molecules. By using large numbers of fibres embedded with different reagents (one of three different fluorophore precursors or one of three oligoamines of differing lengths), the Ohio team produced high-density arrays of attoreactors containing different fluorescent probes. When the arrays are exposed to different metal ions, the fluorescence of the probe molecules is either amplified or quenched to varying degrees.

Rather than reading out the response from each individual attoreactor, the fluorescence of the mat is recorded as a whole, and statistical methods can be used to determine the accuracy of the array in discriminating between the various analytes — with the ten different metal ions used in this study, 100% accuracy was observed.