Phosphate mediated adsorption and electron transfer of cytochrome c. A time-resolved SERR spectroelectrochemical study

Abstract

The study of proteins immobilized on biomimetic or biocompatible electrodes represents an active field of research as it pursues both fundamental and technological interests. In this context, adsorption and redox properties of cytochrome c (Cyt) on different electrode surfaces have been extensively reported, although in some cases with contradictory results. Here we report a SERR spectroelectrochemical study of the adsorption and electron transfer behaviour of the basic protein Cyt on electrodes coated with amino-terminated monolayers. The obtained results show that inorganic phosphate (Pi) and ATP anions are able to mediate high affinity binding of the protein with preservation of the native structure and rendering an average orientation that guarantees efficient pathways for direct electron transfer. These findings aid the design of Cyt-based bioelectronic devices and understanding the modulation by Pi and ATP of physiological functions of Cyt.

Phosphate‐Responsive Biomimetic Nanofluidic Diodes Regulated by Polyamine–Phosphate Interactions: Insights into Their Functional Behavior from Theory and Experiment

“…Therefore, these results can be applied also for other divalent species. However, it is important to mention that it has been previously shown that amine interactions are stronger with phosphates than with other divalent species . Due to the fact that simulations do not acknowledge the chemical nature of each ion but only its charge, we will refer to the ionic species generically as cations (potassium ions), monovalent anions (which include chloride and dihydrogen phosphate ions), and divalent anions (hydrogen phosphate ions) when speaking about the MC simulations.…”

“…However, it is important to mention that it has been previously shown that amine interactions are stronger with phosphates than with other divalent species. [29,30] Due to the fact that simulations do not acknowledge the chemical nature (1)…”

Supramolecular Surface Chemistry: Substrate‐Independent, Phosphate‐Driven Growth of Polyamine‐Based Multifunctional Thin Films

“…On the other hand, specific adsorption of phosphate anions to amino‐terminated self‐assembled monolayers (SAMs) has been recently proved by electrochemical impedance spectroscopy . According to this, orthophosphate anions bind to surface amino groups partially reversing its charge and allowing the interaction with positive proteins as cytochrome c . Specific interactions of Pi with PAH has also been shown to reverse charge in LbL assemblies .…”

Electron-Transfer Rate in Potential-Modulated Redox Reactions with Electro-Active Optical Waveguides

“…(8). From the fitting results, we have determined a surface density saturation of Γsat = (5.9 ± 0.7)pmol/cm 2 …”

“…Impedance measurements where data is collected over a range of modulation frequencies have proven useful for determination of time constants present in electrochemical processes. Usually electron-transfer kinetics of redox species needs be investigated under a variety of interfacial conditions [1][2][3] and electrochemical impedance spectroscopy have been widely deployed for those tasks. [4][5][6][7] However, electrochemical techniques based purely on electrical measurements invariably exhibit inadequate sensitivity to detect small faradaic currents from low concentrations of redox species on the electrode surface.…”