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.

Fusion of a palladium-binding peptide to an archaeal rhodopsin promotes intimate integration of the lipid-embedded membrane protein with a palladium hydride protonic contact. Devices fabricated with the palladium-binding deltarhodopsin enable light-activated conversion of protonic currents to electronic currents with on/off responses complete in seconds and a nearly tenfold increase in electrical signal relative to those made with the wild-type protein.

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Obtaining a better understanding of the adsorption behavior of polymeric nanomedicines is important to properly assess their distribution and fate and to develop successful strategies for minimizing their distribution in the environment. In this study, the adsorption and removal dynamics of a model polymeric nanomedicine of systematically varied sizeslevofloxacin loaded poly(ethyleneglycol-b-3caprolactone)on and from silica surfaces are investigated using a quartz crystal microbalance with dissipation (QCM-D). For all the sizes of the nanomedicine investigated (90 nm, 110 nm, 149 nm, 174 nm, 207 nm, and 305 nm), the adsorbate mass on the silica followed a roughly exponential trend with respect to time during the exposure stage, suggesting first-order adsorption kinetics. The adsorption rate constant decreased with the increasing particle size. Furthermore, we have developed a modified Leveque equation to describe the mass transport and adsorption behavior of the nanoparticulate dispersion inside the QCM-D chamber. The derivation involved the application of a bipolar coordinate system to the continuity, Navier-Stokes, and convective-diffusion equations. The adsorption rate constants calculated using the derived equation were found to match the experimental results well. The derived equation is important not only in the field of environmental science but also in many other fields as QCM-D is heavily used to characterize the dynamic adsorption behavior of various types of materials including polymers, proteins, and nanoparticles.