Interfacing Lipid Bilayer Nanodiscs and Silicon Photonic Sensor Arrays for Multiplexed Protein–Lipid and Protein–Membrane Protein Interaction Screening

Abstract

Soluble proteins are key mediators of many biochemical signaling pathways via direct interaction with the lipid bilayer and via membrane-bound receptors. Components of the cell membrane are involved in many important biological processes, including viral infection, blood clotting, and signal transduction, and as such, they are common targets of therapeutic agents. Therefore, the development of analytical approaches to study interactions at the cell membrane is of critical importance. Herein, we integrate two key technologies, silicon photonic microring resonator arrays and phospholipid bilayer nanodiscs, which together allow multiplexed screening of soluble protein interactions with lipid and membrane-embedded targets. Microring resonator arrays are an intrinsically multiplexable, label-free analysis platform that has previously been applied to studying protein-protein, protein-nucleic acid, and nucleic acid-nucleic acid interactions. Nanodiscs are protein-stabilized lipid assemblies that represent a convenient construct to mimic the native phospholipid bilayer, investigate the effects of membrane composition, and solubilize membrane-embedded targets. Exploiting the natural affinity of nanodisc-supported lipid bilayers for oxide-passivated silicon, we assembled single and multiplex sensor arrays via direct physisorption, characterizing electrostatic effects on nanodisc attachment. Using model systems, we demonstrate the applicability of this platform for the parallel screening of protein interactions with nanodisc-embedded lipids, glycolipids, and membrane proteins.

Whispering gallery mode sensors

“…More recently, membrane nanodiscs as a model system for natural membranes were attached to silicon ring resonators. Specifically, nanodiscs containing the glycolipid receptor GM1 were immobilized to the sensor surface by direct physisorption to test its interaction with the B subunit of cholera toxin (CTB) [325]. Also more recently it was shown that a WGM glass microsphere can be coated by vesicle fusions from a solution of small unilamellar vesicles formed from 1,2-dipalmitoyl-sn-glycero-3-phoshphocholine and 1,2-dioleoyl-sn-glycero-3-phoshphocholine, and cholesterol [326].…”

Advances in the use of nanoscale bilayers to study membrane protein structure and function

“…In this regard, future modifications of the SMA copolymer (size, pendant group stoichiometry and functionalization with molecular tags) will likely be useful in the development of novel experimental applications. In addition to their utility in basic research, these nanoscale bilayers have vast potential for applied technologies, including the development of biocompatible systems for hydrophobic drug delivery and diagnostic applications (Murakami, 2012;Ng, Lovell, Vedadi, Hajian, & Zheng, 2013;Numata et al, 2013), nanoelectronic devices (Goldsmith et al, 2011;Ham et al, 2010), and multiplexed sensor arrays to detect protein interactions (Sloan, Marty, Sligar, & Bailey, 2013). Given the commercial availability of all components required for the synthesis of nanodiscs and SMAPLs/Lipodisqs®, we are sure to see these systems applied to an ever-expanding repertoire of MPs by many independent groups in the coming years.…”

Biomolecular analysis with microring resonators: applications in multiplexed diagnostics and interaction screening

“…(d) The phospholipid composition can be tailored to control physisorption efficiency and modulate protein interactions. Adapted with permission from [44]. Copyright (2013) American Chemical Society.…”

“…The refractive index-based transduction methodology and multiplexing capability of microring resonators also make them highly promising to biomolecular screening and affinity characterization applications [22,31,42-44]. In contrast to endpoint-based methods, which only provide the thermodynamic binding constant, real-time monitoring technologies provide direct access to the kinetic rate constants that govern biomolecular interactions.…”

“…Another recent study probed the interactions of soluble proteins with cell membrane components by integrating the microring resonator arrays with phospholipid bilayer nanodiscs, a synthetic membrane construct [44]. The authors demonstrated the multiplexing capability of this detection approach by simultaneously quantitating four different protein-lipid, protein-carbohydrate, or protein-membrane protein interactions.…”