Self-Assembly of Mammalian-Cell Membranes on Bioelectronic Devices with Functional Transmembrane Proteins

Abstract

Transmembrane proteins (TMPs) regulate processes occurring at the cell surface and are essential gatekeepers of information flow across the membrane. TMPs are difficult to study, given the complex environment of the membrane and its influence on protein conformation, mobility, biomolecule interaction, and activity. For the first time, we create mammalian biomembranes supported on a transparent, electrically conducting polymer surface, which enables dual electrical and optical monitoring of TMP function in its native membrane environment. Mammalian plasma membrane vesicles containing ATP-gated P2X2 ion channels self-assemble on a biocompatible polymer cushion that transduces the changes in ion flux during ATP exposure. This platform maintains the complexity of the native plasma membrane, the fluidity of its constituents, and protein orientation critical to ion channel function. We demonstrate the dual-modality readout using microscopy to characterize protein mobility by single-particle tracking and sensing of ATP gating of P2X2 using electrical impedance spectroscopy. This measurement of TMP activity important for pain sensing, neurological activity, and sensory activity raises new possibilities for drug screening and biosensing applications.

Bioelectrochemical platforms to study and detect emerging pathogens

“… 26 Work by Daniels and Owens has shown that the assembly of SLBs on organic conductive polymers such as PEDOT:PSS, 23 along with the coupling of this material to organic electrochemical transistors (OECTs), can generate a sensor to enable monitoring of pathogen–host interactions that maintains native-like protein mobility and excellent electronic properties (Figure 2 ). 22 , 27 This recent progress in the development of biomimetic interfaces has led to fundamental insights into the structure and function of viruses such as Influenza 28 and the herpes simplex virus (HSV), 29 and could be used to provide similar insights in viruses such as SARS-CoV-2. These platforms have also been used as bioanalytical tools for antiviral drug studies.…”

“… SLB type Detection Shortcoming Ref. Solvent-assisted lipid bilayer formation Protein diffusion in membrane Overly simplified model due to lack of native protein incorporation in the membrane 15 , 16 Protein delivery into SLB via cell bleb on mica, silicon dioxide, glass Allows for study of proteins whose fluidity, orientation, and function has been better preserved Substrates are electrically insulating and rigid, thereby hindering the insertion, function, and mobility of transmembrane proteins 17 – 23 Protein delivery into SLB via cell bleb on conductive polymers such as PEDOT:PSS Allows for detection of pathogen–host interactions that preserve native-like protein mobility and superior electronic properties n/a 22 , 23 , 27 – 31 …”

Correlative microscopy reveals the nanoscale morphology of E. coli-derived supported lipid bilayers

“…One approach to introducing physiologically relevant features into SLBs is the reconstitution of purified membrane proteins into proteoliposomes and the subsequent formation of SLBs from these proteoliposomes. This method has been used in several studies including the study of proteinprotein interactions 1 , membrane-protein interactions and membrane remodelling [2][3][4] , membrane poration 5 , host-pathogen interactions 6 and single receptor activation 7 among others.…”

A conjugated polymer‐liposome complex: A contiguous water‐stable, electronic, and optical interface

“…[ 18–23 ] In addition, a recent research direction explores interfacing supported lipid bilayers (SLBs) with a conductive film based on conjugated polymers with promising results. [ 24–29 ] Thus, we present a brief overview on the origin of the electronic and optical properties of these polymers.…”

“…A promising new approach that further demonstrates the utility of interfacing conjugated polymers with liposomes is investigating SLBs supported by the conjugated polymer when used as an active channel in an organic electrochemical transistor. [ 24–28,54,55 ] Here, the conjugated polymer establishes an electronic communication with the membrane and is an electric read‐out, revealing changes in the permeability and morphology of the SLB. This is a promising platform shown to identify bacterial toxins or antibiotic targets that disrupt bacteria, [ 27 ] elucidate the interaction of compounds [ 26 ] and insertion of proteins with the membrane, [ 25 ] monitor ion channel activity in complex biological SLBs [ 28 ] and in SLBs incorporating gramicidin channel.…”