Polyacrylamide-coated, carbon nanotube (PA/CNT) electrodes were prepared by an inkjet printing process and used to measure pyocyanin and uric acid in a wound fluid simulant at 37 °C. These two molecules are potential indicators of infection, and therefore their detection could prove useful for monitoring wound healing. Pyocyanin is a marker for the common wound bacterium Pseudomonas aeruginosa. Our long-term goal is to use these inexpensive and disposable electrodes to measure biomarkers of wound healing directly. In this proof-of-concept work, studies were performed in a wound fluid simulant to evaluate the stability of the electrodes and their responsiveness for the two bioanalytes. The PA/CNT inkjet-printed electrodes and electrical contacts were stable with unchanging physical and electrochemical properties in the wound fluid simulant over a 7-8-day period at 37 °C. The detection figures of merit for pyocyanin in the simulant at 37 °C were as follows: linear over the physiologically relevant range = 0.10 to 100 μmol L-1 (R2 = 0.9992), limit of detection = 0.10 μmol L-1 (S/N = 3), sensitivity = 35.6 ± 0.8 mA-L mol-1 and response variability ≤4% RSD. The detection figures of merit for uric acid in the simulant at 37 °C were as follows: linear over the physiologically relevant range = 100 to 1000 μmol L-1 (R2 = 0.9997), sensitivity = 2.83 ± 0.01 mA-L mol-1, and response variability ≤4% RSD. The limit of detection was not determined. The PA/CNT electrodes were also used to quantify pyocyanin concentrations in cell-free culture media from different strains of P. aeruginosa. The detected concentrations ranged from 1.00 ± 0.02 to 118 ± 6 μM depending on the strain.

Department of Chemistry Michigan State University 578 S Shaw Lane East Lansing Michigan 48824 United States

Department of Industrial Chemistry Toso Montanari University of Bologna Viale del Risorgimento 4 40136 Bologna Italy

Department of Microbiology and Molecular Genetics Michigan State University 567 Wilson Road East Lansing Michigan 48824 United States

Faculty of Science University Research Centre UNCE Supramolecular Electrochemistry Department of Analytical Chemistry UNESCO Laboratory of Environmental Electrochemistry Charles University Prague Albertov 6 128 43 Prague 2 Czech Republic

Laboratoire d'Electrochimie Physique et Analytique Ecole Polytechnique Fédérale de Lausanne EPFL Valais Wallis Rue de l'Industrie 17 CP 400 CH 1951 Sion Switzerland

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