Electronic control of H+ current in a bioprotonic device with Gramicidin A and Alamethicin

Abstract

In biological systems, intercellular communication is mediated by membrane proteins and ion channels that regulate traffic of ions and small molecules across cell membranes. A bioelectronic device with ion channels that control ionic flow across a supported lipid bilayer (SLB) should therefore be ideal for interfacing with biological systems. Here, we demonstrate a biotic–abiotic bioprotonic device with Pd contacts that regulates proton (H+) flow across an SLB incorporating the ion channels Gramicidin A (gA) and Alamethicin (ALM). We model the device characteristics using the Goldman–Hodgkin–Katz (GHK) solution to the Nernst–Planck equation for transport across the membrane. We derive the permeability for an SLB integrating gA and ALM and demonstrate pH control as a function of applied voltage and membrane permeability. This work opens the door to integrating more complex H+ channels at the Pd contact interface to produce responsive biotic–abiotic devices with increased functionality.

Natural melanin pigments and their interfaces with metal ions and oxides: emerging concepts and technologies

“…Electrical response of eumelanin: amorphous semiconductor model, mixed ionic-electronic conduction, electrochemical interfacial processes, and energy storage Biologic materials, such as proteins, peptides, and melanin, occur naturally in hydrated environments, such that their electrical response includes an important contribution from waterassisted proton transport. [31][32][33][34] The electrical properties of eumelanin have fascinated scientists since the late 1960s. After the observation of a reversible resistive switching in eumelanin pellets reported in 1974 by McGinness et al, [35] the amorphous semiconductor model was adopted to explain the strong hydration dependence of the conductivity.…”

Soft and Ion‐Conducting Materials in Bioelectronics: From Conducting Polymers to Hydrogels

“…Hydrogels are intrinsically ion‐conducting due to high water content that provides a good environment for ions to be mobile. This ionic conductivity is useful for translation between devices and tissue at the bioelectronic interface . Hydrogels can be used in devices such as protonic field‐effect transistors (FET) that use palladium (Pd) and palladium hydride (PdH x ) as a transducer between H + and e − ( Figure ) .…”

“…The FET channel is made of an H + conducting hydrogel, maleic‐chitosan (poly (β‐(1,4)‐ N ‐Maleoyl‐D‐glucosamine)), which is a polysaccharide chitin derivative with high proton conductivity . Protonic bioelectronic devices can modulate pH in electrolytes and monitor metabolic reactions, control bioluminescence with pH, and interface with ion channels . In Figure 3b, an ion channel integrated with a Pd/PdH x contact was used to regulate protons flow across a supported lipid layer (SLB) .…”

A Short Review of the Architecture and Computational Analysis in the Design of Graphene Based Bioelectronic Devices

“…These capabilities led the continuum electrodiffusion models to be more favoured for modelling the interaction of ion channels in biological processes (53,58,59) and for describing ionic transport in ceramic and polymeric membranes as well as modelling the transport of charged particles in semiconductors. (53,58,59) Figure 7 depicts a schematic of an ion channel bioprotonic device (60) that could be considered for the general case of bioelectronic device architecture. A supported lipid bilayer (SLB) (orange spheres with tails) is sandwiched in an electrolytic layer (a polymeric membrane, graphene membrane, or a liquid electrolyte).…”

“…Schematic representation of common bioelectronic device architecture. (60) the chemical potential gradient is the driving force for transport as well as the electrostatic potential,…”