Dropsens model stat300

The morphology of the electrode surface was investigated using scanning electron microscopy (SEM) (Field Electron and Ion (FEI)) (FEI, Hillsboro, OR, USA). The elemental analysis was performed using an energy dispersive analysis of X-rays (EDX) (EDAX, Mahwah, NJ, USA). The electrochemical reduction of gold ions to gold nanoparticles was performed using a potentiostat from Metrohm-DropSens Model µStat300. Electrochemical impedance spectroscopy (EIS) data were performed using an ISX-3 impedance analyzer (Sciospec, Bennewitz, Germany) in phosphate-buffered saline (0.1 M PBS, pH 7.4) containing 5.0 mM Fe(CN)₆^4−/3− couple (1:1) as the redox probe. The reference and counter electrodes were made of graphene. The interdigitated electrodes (sensing electrodes) were made of graphene–gold.

The surface morphologies of the electrodes were characterized using scanning electron microscopy (SEM) (Field Electron and Ion (FEI)) (FEI, Hillsboro, OR, USA.). The cyclic voltammetry (CV) studies were performed using a potentiostat from Metrohm-DropSens Model µStat300 (Llanera, Spain). The elemental analysis was performed using an energy dispersive analysis of X-rays (EDX) (EDAX, Mahwah, NJ, USA). The attenuated total reflectance spectrum (ATR) study was performed by using a Nicolet iS50 Fourier transform infrared spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). Electrochemical impedance spectroscopy (EIS) experiments were carried out using an ISX-3 impedance analyzer (Sciospec, Bennewitz, Germany) in phosphate-buffered saline (0.1 M PBS, pH 7.4) containing 5.0 mM Fe(CN)₆^4−/3− couple (1:1) as the redox probe. An alternating current (AC) voltage of 10 mV and direct current (DC) voltage of 0.13 V were applied over a frequency range of 100 kHz to 0.1 Hz and the output signal was acquired using an EIS spectrum analyzer (EISSA) software.