SENSORS: Multi-Anion Sensing by Conductive Polymers with Dual Mode of Signal Transduction

Bowling Green State University, Bowling Green OH

Investigators

Abstract

The objective of this proposal is the development and study of novel, inherently conductive polymer thin films that will be used for selective sensing of inorganic anions with emphasis on phosphate- and phosphonate-related species. The detection and quantitative measurement of levels of phosphate and phosphonate anions is an important requirement for drug testing and pharmacological (pharmacokinetic) studies as well as environmental monitoring. The sensing of these anions, found in fertilizers and pharmaceuticals, is aimed at aqueous environment and low concentrations (< 10 -6 mol/l). Sensor materials capable of reacting to the presence of analyte by change of optical (color/emission) and electrical properties in a simultaneous regime will be developed. The combination of two independent modes of signal transduction will improve the selectivity and reliability of the sensing process. This will be accomplished by preparing novel polythiophene-based polymer materials with anion-selective receptors integrated into the pi-conjugated backbone of the polymer. The critical knowledge amassed during the PI's previous studies will be used to prepare monomers bearing suitable receptors and electropolymerizable thiophene derivatives. These sensor monomers will be electrochemically polymerized on the surface of transparent electrodes. Such transparent electrodes coated with anion sensor material will be used to fabricate spectroelectrochemical cells, which will allow for investigation of anion binding using two modes of signal transduction: changes in optical and electrical properties. The two-mode signal transduction is expected to increase the accuracy of the whole sensing process, enhance specificity and make these materials capable of anion sensing in multi-anion environments. Reliable anion sensing in multi-anion environments will be achieved by using individually addressable transparent microelectrodes with multiple deposited materials bearing different receptors. Alternatively, similar effect may be achieved by copolymerization of two or more sensor monomers bearing different receptor units. These sensor-coated electrodes will be used to build sensor devices and will be tested in multi-analyte environments. The intellectual merit of the proposed research is diverse. Polymer materials capable of sensing of anionic substrates in polar/aqueous solutions at low concentrations are rare. Efforts toward implementing successful molecular sensors into polymer materials, which may allow the development of robust/stable materials with improved performance, are therefore desirable. Particularly important in this regard is the idea of improved reliability and accuracy of the sensing process by simultaneous implementation of two independent modes of signal transduction. This may allow for reliable sensing of anionic substrates that are otherwise difficult to sense. The approach of detecting the anion by change of two variables in a simultaneous regime may allow for sensing of multiple anionic analytes. This is particularly important because, despite the great need, materials and devices that would provide both high selectivity and allow for multi-analyte sensing have not been successfully prepared so far. In terms of the broader impacts, this PI would like to emphasize that the proposed research will serve for the advancement of general knowledge by investigating novel sensor materials. The proposed multi-anion sensors would be highly useful in a wide variety of applications, mostly medical and environmental, for example to allow for a precise monitoring of drug metabolization thus stimulate a development of novel drug-metabolization assays. The development and investigation of such novel, conductive polymers with dual mode of signal transduction for sensing anionic multi-analytes represents a venture into an emerging and far reaching area of research and technology. This PI's team will also take active part in an interdisciplinary discussion focused on various aspects of anion sensing through publication and active participation in scientific meetings. Last but not least, the broader community will benefit through the advancement of education thus contributing to professional training of qualified workforce.