Nanograss Array Boron-Doped Diamond Electrode for Toxicity Sensor with Shewanella loihica PV-4 in Bioelectrochemical Systems

A nanograss array boron-doped diamond (BDD) electrode-based toxicity sensor, using shewanella loihica PV-4 planktonic cells as recognition element in bioelectrochemical systems (BES), was developed for detection of tobramycin. An oxidative 3.3 A/cm² current was generated on the nanograss array BDD electrode poised at 0.2 V in the BES, in the presence of S. loihica PV-4 cells. After addition of tobramycin in the range of 1.0–20.0 g/mL, the current was decreased from 3.0 A/cm² to 1.3 A/cm², with current inhibition ratio exponentially increased from 7.6% to 59.6%. The electrochemical responses from tobramycin concentrations in the nanograss array BDD electrode-based BES were further evaluated by cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The redox peak currents of CVs were decreased exponentially with tobramycin concentrations and CV profiles changed from peak shape to nearly plateau shape. The semicircle diameter of EIS increased with the increase of tobramycin concentration. These results provide preliminary information about tobramycin concentration responses in the nanostructured BDD electrodes-based BES as a toxicity sensor.