Electropolymerized Layersas Selective Membranesin First Generation Uric Acid Biosensors

Electropolymerized films that can serve as semi-permeable membranes and provide selectivity within a xerogel-based, 1stgeneration biosensor assembly are explored in this study. Layered biosensing schemes of this nature rely primarily upon an electropolymerized ad-layer to supplement the xerogel and provide effective selectivity for detection of a targeted analyte. While effective electropolymers have been established for glucose sensing, the adaptation of the strategy to other analytes of clinical importance hinges upon the systematic evaluation of electropolymerized films to identify a selective film. Uric acid is a key species in the diagnosis/monitoring of a number of diseases and conditions. An effective uric acid biosensor, exhibiting high selectivity against common interferent species while maintaining uric acid sensitivity across physiologically relevant concentrations, would represent significant sensor development. Cyclic voltammetry allows for initial electropolymerization as well as the verification of polymer-modified electrodes. By forming electropolymerized films at glassy carbon electrodes, the sensitivity and permeability index toward uric acid and other interferents is readily measured via amperometric current responses. Of the significant number of polymer films examined in the study, only those films formed from luminol/aniline and luminol/Nafion mixtures showed positive selectivity coefficients for uric acid when incorporated into the layered xerogel schemes. The use of these specific mixed polymer films within the biosensing scheme resulted in well-defined amperometric responses to uric acid, linear calibration curves across clinically relevant uric acid concentrations, and effective selectivity for uric acid with discrimination against all major interferents except acetaminophen. The demonstrated and systematic evaluation of a specifically selective electropolymerized film is an important advancement for uric acid biosensor development as well as further adaptation of biosensing strategies involving polymer interfaces to other targeted analytes