Macroscopic Models for the Bioelectronic Interface of Engineered Artificial Membranes

Abstract

In this chapter, we present the formation and modeling techniques of two important sensing devices built out of engineered artificial membranes: the Ion Channel Switch (ICS) biosensor, and the Electroporation Measurement Platform (EMP). The ICS biosensor can be used to detect femto-molar concentrations of analyte species in an electrolyte solution, and the EMP is used to study the dynamics of electroporation in engineered membranes. The engineered membrane in the ICS and EMP are design to mimic the electrophysiological properties of real cell membranes. Common to both platforms is the bioelectronic interface for performing electrical measurements. Experimental measurements of the two platforms are performed by estimating the current response of the engineered membrane which depends on the charging dynamics at the bioelectronic interface and membrane, as well as dynamics of aqueous pores and conducting ion-channels in the membrane.

Appendix

All experimental measurements using the ICS and EMP, unless otherwise stated, were conducted at 20 $^{\circ }$C in a phosphate buffered solution with a pH of 7.2, and a 0.15 M saline solution composed of Na$^+$, K$^+$, and Cl$^-$. At this temperature the tethered membrane is in the liquid phase. A pH of 7.2 was selected to match that typically found in the cellular cytosol of real cells. The forward and reverse reaction rates in Table 2 are obtained from [10, 23, 50]. The electroporation parameters $\alpha , q, C, D, r_m$ are obtained from [27, 32, 39, 40], $\gamma , \sigma$ from [41], and $W_\text {es}(r)$ and $G_p(r)$ from [13]. Using impedance measurements it was determined that the fractional order operator p is in the range of 0.95 to 0.98 suggesting that a diffusion-limited process is present at the bioelectronic gold interface of the tethered archaebacterial membrane. The associated capacitance $C_{dl}$ is in the range of 120–180 nF.