A Semisolid Polymer-Based Electrochemical Cell for Electrostimulated Lactate Detection

A fully organic electrochemical cell was designed for the immobilization of l-lactic acid (LLA) and for the detection of lactate (LA) oxidation to pyruvate, representing a nonenzymatic sensor for in vitro LA analyses. The novelty relies on the preparation of a bilayer semiconducting electrode, composed of an inert and biocompatible poly-(propylene) (PP) film and a coating of doped poly-(3,4-ethylenedioxythiophene) (PEDOT), which served as both working and counter electrodes, for the monitoring of the LA/pyruvate redox reaction and the quantification of these biomolecules using electrochemical tools and UV-visible spectroscopy, respectively. An advantageous characteristic of PP/PEDOT-LA electrodes was the faster pyruvate release under electrical stimulation (by pulsed short-time voltage applications), reaching 100% conversion in 360 min. Such results were promoted by the replacement of aqueous electrolytes for a highly stable hydrogel, constituted of poly-(γ-glutamic acid) (γ-PGA) cross-linked with cystamine, which was employed as a porous and permeable semisolid electrolyte in the polymer-based electrochemical cell (PEC). The resulting insights would help to improve the analytical methods currently employed for the quantification of LA in the biomedical, food, and beverage industries.