Introduction

This chapter describes the construction and operation of three important tetheredmembrane- based sensor platforms, namely, the pore formation measurement platform (PFMP), the electroporation measurement platform (EMP), and the electrophysiological response platform (ERP). These three platforms are constructed to mimic real cell membranes and allow experimental measurements of the dynamics and biochemical reaction pathways present in biological membranes (e.g., the physiochemical properties of membranes). As such, the results from the PFMP, EMP, and ERP elucidate the structural and dynamic properties of real biological membranes. An understanding of the structural and dynamic properties of biological membranes’ interaction with macromolecules is also useful for rational drug design and therapeutic protocols as discussed in §3.7. A schematic diagram of these platforms is provided in Figure 6.1; recall that these platform devices were introduced in Chapter 3.

The PFMP, EMP, and ERP are designed to perform specific tasks. The PFMP is designed to estimate the reaction dynamics of pore-forming peptides and proteins. The dynamics of pore-forming peptides and proteins are crucial to the attack and defense mechanisms of biological organisms. Understanding the chemical kinetics of poreforming peptides and proteins provides vital information of use to pharmacologists to target specific classes of peptides and proteins for in-depth pharmaceutical screening of novel drugs. The principal operation of the PFMP is that changes in the membrane conductance can be related to the number of formed pores in the membrane. These changes in membrane conductance can be measured experimentally using impedance measurements. The EMP is designed to study the dynamics of electroporation in tethered membranes. Electroporation is a process in which a transmembrane potential induces the formation of aqueous pores in the tethered membrane. The formation of aqueous pores is important for the transport of molecules through the membrane. The ERP is designed to measure the conductance dynamics of embedded ion channels and to measure the electrophysiological response of cells grown on the surface of the tethered membrane. These results are important for drug screening and diagnosis of channelopathic diseases.