Nova 1

The corrosion resistance of the AR, CHT and LHT samples was assessed by means of electrochemical measurements. Linear polarization measurements were performed using an Autolab PGSTAT 302N potentiostat system, which was driven by NOVA 1.10 software (Eco-chemie, Utrecht, Netherlands). The measurements were achieved using a conventional three-electrode setup, where a test sample with approximately 0.2 cm² exposed surface area was placed in 3.5% NaCl (pH 7) solution at 23 °C. A constant potential scan rate of 1 mV·s⁻¹ was used. All potentials were computed with respect to Ag/AgCl, with a 3 mol/L KCl electrode as a reference electrode. A platinum electrode was used as the counter electrode for current measurement.

The electrochemical measurements were conducted at room temperature using Autolab PGSTAT204 and NOVA 1.10 software (Metrohm, Netherlands) using a mixture of 10 mM ferri/ferrocyanide and 0.5 M KCl in 1 × PBS solution as a redox mediator. Graph analysis was conducted using Origin 2017. Changes in the electrochemical properties of the MWCNT-PDMS, COOH-CNT/MWCNT-PDMS, Ab/COOH-CNT/MWCNT-PDMS, and BSA/Ab/COOH-CNT/MWCNT-PDMS electrodes were measured using cyclic voltammetry (CV), DPV, and electrochemical impedance spectroscopy (EIS). Optimization and HA protein detection experiments, and selectivity and reproducibility tests were performed using DPV.

The electrochemical modification of graphitic electrodes and the measurements by cyclic voltammetry (CV) were performed by using an Autolab PGSTAT 30 (Metrohm, Utrecht, The Netherlands) potentiostat/galvanostat. which was operated by the Nova 1.10 software (Metrohm). The Ag/AgCl in 3 M KCl electrode and silver wire coated with AgCl were used as the reference electrodes in aqueous solutions and in nonaqueous media, respectively. Graphite rod (3 mm in diameter and length of 3 cm) as a working electrode was polished by abrasives and sonicated in acetone for 15 min. Sides of this electrode were covered with rubber, and only the bottom of the electrode with a surface area of 0.071 cm² was used. A titanium plate with a surface area of 1 cm² was used as an auxiliary electrode for the electrochemical measurements. The surfaces of the graphite rod and the polycarbazole layer were imaged by a Hitachi TM3000 (Hitachi-HighTech, Tokyo, Japan), scanning electron microscope (SEM) at 10 kV accelerating voltage in vacuum. Raman spectra of the materials were measured by a WiTec Alpha 300 R Raman (WITec, Ulm, Germany) spectrophotometer equipped with a laser of 534 nm.

For the H₂O₂ measurements, a screen-printed electrode (Drop-Sens, Llanera, Spain) with a surface covered with Prussian blue/glassy carbon has been used. The functionality of the chip electrode has been checked with a cyclic voltammogram in the range of −0.4–1.1 V. A typical pattern of the redox reaction at the chip electrode proves a calibrated voltammogram. The measurement was integrated into a flow system that continuously pumps a PBS buffer (pH 4.6, adjusted with 3 M KCl) into the measuring circuit with a rotational speed of 16 U/min. Due to the disintegration of H₂O₂ in alkaline surroundings, the pH of the buffer solution has to be below pH 7 [27 (link)]. At the outset, PTW was produced with the plasma device as described earlier. Subsequently, 500 μL of the sample was injected into the flow system and was measured in real-time. A potentiostat (Autolab PGSTAT101, Metrohm, Filderstadt, Germany) has been used. Data acquisition and evaluation have been performed on the software Nova1.10 (Metrohm, Filderstadt, Germany).