Microfluidic Nanopore Array for Stable Lipid Bilayers
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Solution Overview
Problem
Current methods for creating artificial lipid bilayers for studying membrane proteins lack suitable high-throughput screening models with controlled lipid composition and preserved structural integrity, particularly due to issues with lipid mobility and protein stability, especially when spanning apertures greater than 1 micron.
Innovation Solution
A microfluidic nanopore array with hydrophilic polydimethylsiloxane (PDMS) substrates featuring buffer-filled hemispherical cavities supports a spanning lipid bilayer and reconstituted membrane proteins, using the Langmuir Blodgett technique and vesicle fusion to achieve defect-free bilayers that remain stable for several days across a range of cavity sizes from 620 nm to 5 micrometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If Supported Lipid Bilayers (SLBs) are used as artificial bilayer models, then the bilayer structure is stable, but the mobility of lipids and membrane proteins is dramatically lowered compared with native cell membranes
Solution Approach 1:
The invention divides the planar substrate into multiple discrete microwell cavities, each acting as an independent compartment. This segmentation allows the bilayer to be supported at discrete locations rather than continuously, creating gaps between support points that enable lateral mobility while maintaining structural stability at each well location.
Solution Approach 2:
The microwell cavities act as intermediary structures between the solid substrate and the lipid bilayer. These cavities provide a geometric constraint that supports the bilayer structure while the aqueous environment within the wells allows lipids and proteins to diffuse freely, mediating between the conflicting requirements of stability and mobility.
2Stability of the object's composition
If tethered bilayer lipid membranes (t-BLMs) are used with a spacer between the bilayer and surface, then stability to the lipid bilayers is improved, but diffusion coefficients of lipids are not significantly improved compared to SLBs
Solution Approach 1:
Instead of using a continuous spacer layer that restricts diffusion, the invention segments the support structure into discrete microwell cavities. This segmentation removes the restrictive spacer between the bilayer and substrate, allowing lipids to diffuse freely while the cavity geometry provides the necessary structural support and spacing.
Solution Approach 2:
The invention changes the geometric configuration from a flat, continuous support structure to a three-dimensional cavity structure. This geometric transformation fundamentally alters the interaction between the bilayer and substrate, enabling high diffusion coefficients while maintaining stability through the cavity walls rather than molecular spacers.
3Speed
If lipid bilayers are spanned across nano- and micro-sized apertures to obtain sufficient separation from substrates, then lateral mobility is improved, but stability is poor due to retention of organic solvents
Solution Approach 1:
The invention performs preliminary action by pre-forming the microwell cavity array on the substrate before assembling the lipid bilayer. This pre-formed geometric structure provides a stable framework that guides bilayer formation and ensures proper spacing from the substrate, preventing organic solvent retention while enabling high lateral mobility from the outset.
Solution Approach 2:
The microwell cavity array creates a porous-like structure at the microscale, providing pathways and spaces that allow the bilayer to be separated from the substrate while maintaining structural integrity. The cavity geometry mimics the beneficial effects of porous structures in enabling mobility without the harmful effects of organic solvent retention.
4Loss of substance
If pore-spanning lipid bilayers are formed using design methods in restricted conditions, then solvent-free bilayers are achieved, but incorporation and manipulation of membrane proteins remains difficult
Solution Approach 1:
The microwell cavity array provides a universal platform that accommodates various membrane protein incorporation methods and manipulation techniques. The standardized cavity geometry serves multiple functions: supporting the bilayer, enabling protein incorporation, facilitating manipulation, and allowing high-throughput screening, making the system versatile for different experimental needs.
Solution Approach 2:
The invention changes the physical parameters of the support structure from nanoscale to microscale cavity dimensions, which fundamentally alters the properties of the spanning bilayer. This parameter change enables the bilayer to be formed without organic solvents while simultaneously improving the ease of membrane protein incorporation and manipulation, as the larger cavity size provides better mechanical stability and easier access for protein handling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the creation of stable, bio-relevant lipid bilayer models with high lateral mobility of lipids and proteins, comparable to native cell membranes, facilitating the study of membrane protein behavior and drug interactions with improved stability and versatility.
Implementation Method 1
array having free-spanning lipid layers over buffer-filled microcavities... A bilayer prepared using Langmuir Blodgett or Langmuir Blodgett Schaeffer technique
Implementation Method 2
followed by fusion with small uni-lamellar vesicles to form an array
Implementation Method 3
Lateral diffusion of lipids and membrane proteins within the membrane regulate the distribution of membrane components... diffusion coefficients of the lipids measured were not significantly improved compared to those measured for SLBs
Data Source
AI summary
A microfluidic array supporting a lipid bilayer assembly on which membrane proteins can be assembled is described. The array is formed from a hydrophilic polymeric substrate or metal substrate comprising a planar surface with a plurality of individual spherical depressions formed therein. Each of the depressions are configured to have a diameter greater than 1 μm and containing an aqueous solution. Across each of the depressions is provided a lipid layer. Each of the plurality of individual depressions comprise arcuate side walls extending downwardly into the substrate from the planar surface.