Abstract
The integration of supported lipid membranes with surface-based nanoplasmonic arrays provides a powerful sensing approach to investigate biointerfacial phenomena at membrane interfaces. While a growing number of lipid vesicles, protein, and nucleic acid systems have been explored with nanoplasmonic sensors, there has been only very limited investigation of the interactions between solution-phase nanomaterials and supported lipid membranes. Herein, we established a surface-based localized surface plasmon resonance (LSPR) sensing platform for probing the interaction of dielectric nanoparticles with supported lipid bilayer (SLB)-coated, plasmonic nanodisk arrays. A key emphasis was placed on controlling membrane functionality by tuning the membrane surface charge vis-à-vis lipid composition. The optical sensing properties of the bare and SLB-coated sensor surfaces were quantitatively compared, and provided an experimental approach to evaluate nanoparticle–membrane interactions across different SLB platforms. While the interaction of negatively-charged silica nanoparticles (SiNPs) with a zwitterionic SLB resulted in monotonic adsorption, a stronger interaction with a positively-charged SLB resulted in adsorption and lipid transfer from the SLB to the SiNP surface, in turn influencing the LSPR measurement responses based on the changing spatial proximity of transferred lipids relative to the sensor surface. Precoating SiNPs with bovine serum albumin (BSA) suppressed lipid transfer, resulting in monotonic adsorption onto both zwitterionic and positively-charged SLBs. Collectively, our findings contribute a quantitative understanding of how supported lipid membrane coatings influence the sensing performance of nanoplasmonic arrays, and demonstrate how the high surface sensitivity of nanoplasmonic sensors is well-suited for detecting the complex interactions between nanoparticles and lipid membranes.
Highlights
Ongoing advances in micro- and nanofabrication lend excellent potential for interfacing sensor technologies with biologically relevant components such as viruses [1,2,3], exosomes [4,5,6], and nanoparticles [7,8]
We utilized nanoplasmonic sensing platforms that consist of randomly distributed gold nanodisks utilized nanoplasmonic sensing platforms that consist of randomly goldsilica on a glassWe surface, and the entire sensor surface was conformally coated with distributed a 10-nm thick nanodisks on a glass surface, and the entire sensor surface was conformally coated with a 10-nm overlayer (Figure 1A)
The surface, we demonstrated for the first time a quantitative approach to determine the absolute proximity to the surface, we demonstrated for the first time a quantitative approach to determine the values of the respective supported lipid bilayer (SLB) separation distances from the surface based on localized surface plasmon resonance (LSPR) measurements
Summary
Ongoing advances in micro- and nanofabrication lend excellent potential for interfacing sensor technologies with biologically relevant components such as viruses [1,2,3], exosomes [4,5,6], and nanoparticles [7,8]. By fabricating sensor arrays on solid supports, a wide range of surface-sensitive measurement techniques can be utilized to investigate the binding and conformational properties. Sensors 2017, 17, 1484 of biomacromolecules and soft matter interacting with nanostructures. Within this scope, one of the most promising directions involves engineering nanostructured sensing arrays to probe interactions involving cell membranes [9,10,11]. Cell membranes are a key component of biological life, and membrane integrity is important for biological functions such as cellular compartmentalization and biochemical signaling [12,13]. The topic is interesting because supported lipid membrane fabrication is challenging and a vast number of functionalization possibilities exist by selecting the appropriate membrane composition. Supported lipid membranes are formed on silica-coated surfaces, which promote spontaneous bilayer formation whereas the formation process is less favorable on other materials such as gold and titanium oxide [14]
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