Protein film voltammetry (PFV) and film preparation took place in a N2 atmosphere glovebox (Belle Technology Ltd, O2 < 2 ppm). All measurements were conducted at room temperature, using a square basal-plane pyrolytic graphite electrode (square BPPGE; geometric area of 0.09 cm2) as the working electrode in mixed buffer (15 mM sodium 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (Na-HEPES, 15 mM sodium 2-(N-morpholino)ethanesulfonate (Na-MES), 15 mM sodium 2-(N-cyclohexylamino)ethanesulfonate (Na-CHES), 15 mM sodium tris(hydroxymethyl)methylamino]propanesulfonate (Na-TAPS) and 15 mM sodium acetate). The pH was adjusted to the required value (pH 3.0 – 13.0), using NaOH and HCl. A saturated calomel electrode (SCE, Hg/HgCl2 in saturated potassium chloride, KCl) was used as a reference and a platinum wire was used as the counter electrode. Electrochemical measurements were performed using an EmStat4R [SNS] potentiostat (PalmSens) operated through PSTrace software. Signal processing, fitting and baseline subtraction was performed using QSoas software. The corrections for this study were ⁓ +244 mV. Before protein adsorption, the PGE was polished with P2500 grit sandpaper (Kemet) and rinsed, then 2 μL of ≈0.5 mM protein was applied onto the electrode surface and was left to dry for ~ 5 min to form a film. The electrode was subsequently transferred to the electrochemical cell to carry out the electrochemical measurements.