(736e) Amperometric Detection and Quantification of Perchlorate in Groundwater Supplies Using a Highly Sensitive Nanostructured Electropolymerized PEDOT Biosensor

There has been a steady rise in the release of perchlorate (ClO₄^-), a prominent contaminant associated with the discharge of ammonium perchlorate from military and aerospace installations over the past few decades. Its remarkable recalcitrance to environmental degradation on account of its high activation energy coupled with high aqueous solubility has made it possible for ClO₄^- to persist in the ecosystem for a long time and make its way to the top of the food-chain. Severe cases of thyrotoxicosis are known to occur when the mammalian thyroid gland absorbs similar sized perchlorate ions instead of the iodide ions. Ever since the addition of ClO₄^- to the Contaminant Candidate list, there has been an increased effort to develop detection and quantification protocols for field tests that provide instant yet reliable results. In this study, we suggest the use of a portable, highly sensitive, fast acting enzymatic biosensor capable of measuring minute concentrations of perchlorate. Our perchlorate biosensor would consist of a sensing element in the form of perchlorate reductase, class of enzymes capable of reducing perchlorate to chlorite immobilized on a conductive polymer platform responsible for generating an amperometric response. Given their conductive nature, several polymers such as polyacetylene, polyaniline and polypyrrole have been used in the past for incorporation in sensor technology. In our work, we use poly(3,4-alkylenedioxypyrrole) (PEDOT), a conducting polymer resistant to nuclueophilic attack at the β-position. The controlled growth of PEDOT nanoarrays of desired morphologies using template assisted electropolymerization offers great potential to immobilize a host of bioactive components. In our work, we show the incorporation of perchlorate reductase on free-standing PEDOT nano-arrays using self-assembly techniques. The use of mediators in establishing faster electrical connection between the redox sites of the enzyme and the electrode surface is well-known. We propose to investigate the role of methyl viologen, a cationic mediator in shuttling electrons to establish fast yet accurate amperometric response. All electrochemical measurements were made using a CH instruments-model 650 A workstation using the conventional three electrode system.