Charge-selective membrane protein patterning with proteoliposomes (original) (raw)
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Arrays of lipid bilayers and liposomes on patterned polyelectrolyte templates
Journal of Colloid and Interface Science, 2006
This paper presents novel methods to produce arrays of lipid bilayers and liposomes on patterned polyelectrolyte multilayers. We created the arrays by exposing patterns of poly(dimethyldiallylammonium chloride) (PDAC), polyethylene glycol (m-dPEG) acid, and poly(allylamine hydrochloride) (PAH) on polyelectrolyte multilayers (PEMs) to liposomes of various compositions. The resulting interfaces were characterized by total internal reflection fluorescence microscopy (TIRFM), fluorescence recovery after pattern photobleaching (FRAPP), quartz crystal microbalance (QCM), and fluorescence microscopy. Liposomes composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoylsn-glycero-3-phosphate (monosodium salt) (DOPA) were found to preferentially adsorb on PDAC and PAH surfaces. On the other hand, liposome adsorption on sulfonated poly(styrene) (SPS) surfaces was minimal, due to electrostatic repulsion between the negatively charged liposomes and the SPS-coated surface. Surfaces coated with m-dPEG acid were also found to resist liposome adsorption. We exploited these results to create arrays of lipid bilayers by exposing PDAC, PAH and m-dPEG patterned substrates to DOPA/DOPC vesicles of various compositions. The patterned substrates were created by stamping PDAC (or PAH) on SPS-topped multilayers, and m-dPEG acid on PDAC-topped multilayers, respectively. This technique can be used to produce functional biomimetic interfaces for potential applications in biosensors and biocatalysis, for creating arrays that could be used for high-throughput screening of compounds that interact with cell membranes, and for probing, and possibly controlling, interactions between living cells and synthetic membranes.
Langmuir, 2011
Supported lipid bilayers (SLBs) formed on many different substrates have been widely used in the study of lipid bilayers. However, most SLBs suffer from inhomogeneities due to interactions between the lipid bilayer and the substrate. In order to avoid this problem, we have used microcontact printing to create patterned SLBs ontop of ethylene glycol-terminated self-assembled monolayers (SAMs). Glycol-terminated SAMs have previously been shown to resist absorbance of biomolecules including lipid vesicles. In our system, patterned lipid bilayer regions are separated by lipid monolayers, which form over the patterned hexadecanethiol portions of the surface. Furthermore, we demonstrate that α-hemolysin, a large transmembrane protein, inserts preferentially into the lipid bilayer regions of the substrate.
A Novel Method To Fabricate Patterned Bilayer Lipid Membranes
Langmuir, 2007
We introduce a new method for forming tethered bilayer lipid membranes on surfaces patterned using a photocleavable self-assembled monolayer (SAM). A SAM terminated with a hydrophobic fluorocarbon residue was bound to a gold surface through a link containing a photocleavable ortho-nitrobenzyl moiety. Hydrophilic regions were produced by irradiation with soft UV (365 nm) through a photomask. The patterned surface was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Tethered bilayer lipid membranes with well-defined bilayer and monolayer regions were then formed by exposure to egg PC vesicles. The membranes had resistance and capacitance values of 0.52 MΩ‚cm 2 and 0.83 µF‚cm -2 , respectively.
Biophysical Journal, 2003
We present a new method for creating patches of fluid lipid bilayers with conjugated biotin and other compounds down to 1 mm resolution using a photolithographically patterned polymer lift-off technique. The patterns are realized as the polymer is mechanically peeled away in one contiguous piece in solution. The functionality of these surfaces is verified with binding of antibodies and avidin on these uniform micron-scale platforms. The biomaterial patches, measuring 1 mm-76 mm on edge, provide a synthetic biological substrate for biochemical analysis that is ;1003 smaller in width than commercial printing technologies. 100 nm unilamellar lipid vesicles spread to form a supported fluid lipid bilayer on oxidized silicon surface as confirmed by fluorescence photobleaching recovery. Fluorescence photobleaching recovery measurements of DiI (1,3,39, )) stained bilayer patches yielded an average diffusion coefficient of 7.54 6 1.25 mm 2 s ÿ1 , equal to or slightly faster than typically found in DiI stained cells. This diffusion rate is ;33 faster than previous values for bilayers on glass. This method provides a new means to form functionalized fluid lipid bilayers as micron-scale platforms to immobilize biomaterials, capture antibodies and biotinylated reagents from solution, and form antigenic stimuli for cell stimulation.
Elaboration of micro-domains of supported bilayer membranes using micro-contact printing
Microelectronic Engineering, 2007
Combining patterning methods with the ability of biomolecules to arrange themselves in organized molecular structures is a very interesting approach for building complex 3D architectures. Along this route, that combines nano-patterning with bottom-up assembly, we have used micro-contact printing (lCP) for fabricating self assembled supported phospholipids membranes that can mimic cell membranes and their compartments due to the ability of the technique to shape domains at the micron scale. Micro-domains of lipidic membranes were obtained, though the selective fusion of liposomes on SiO 2 surfaces printed with bovins serum albumine patterns. We found that BSA pattern obtained by lCP prevents the fusion of liposomes. This result was confirmed by atomic force microscopy, fluorescence imaging and FRAP experiments.
Colloids and Surfaces B: Biointerfaces, 2012
In this work, we propose a reliable microcontact printing (CP) process for generating Patterned Supported Phospholipids Bilayer (P-SPB) confined by Poly-l-(lysine)-grafted-polyethylene(glycol) (Pll-g-PEG) molecular barriers. The efficiency of Pll-g-PEG for inhibiting the fusion process of incubated liposome was first analyzed by Quartz Micro Balance (QCM) measurements. The quality and stability of Pll-g-PEG patterns were then both verified by fluorescence microscopy and Atomic Force Microscopy (AFM) in liquid media. The micro domains of P-SPB produced were stable in liquid environment during several weeks and also during AFM imaging. This exceptional stability is a clear improvement compared to previous studies involving proteins as confinement barriers.
Preparation and Dynamic Patterning of Supported Lipid Membranes Mimicking Cell Membranes
Methods in Molecular Biology, 2011
In this chapter, we describe standardized protocols for the self-assembly of supported lipid bilayers (SLBs) from liposomes with lipid compositions mimicking eukaryote and prokaryote cell membranes. Such SLBs can also contain lipids with polymeric and glycosylated headgroups. Furthermore, we present protocols on how to manipulate the adsorption and desorption of membranes on indium tin oxide (ITO) electrodes, which allows for the creation of patterned and in situ regenerated SLB arrays that can be used to study electrochemically mediated membrane processes in a microarray format.
Controlled delivery of proteins into bilayer lipid membranes on chip
Lab on a Chip, 2007
The study and the exploitation of membrane proteins for drug screening applications requires a controllable and reliable method for their delivery into an artificial suspended membrane platform based on lab-on-a-chip technology. In this work, a polymeric device for forming lipid bilayers suitable for electrophysiology studies and biosensor applications is presented. The chip supports a single bilayer and is configured for controlled protein delivery through on-chip microfluidics. In order to demonstrate the principle of protein delivery, the potassium channel KcsA was reconstituted into proteoliposomes, which were then fused with the suspended bilayer on-chip. Fusion of single proteoliposomes with the membrane was identified electrically. Single channel conductance measurements of KcsA in the on-chip bilayer were recorded and these were compared to previously published data obtained with a conventional planar bilayer system.
Journal of the American Chemical Society, 1999
This paper presents a novel method for supporting planar lipid bilayers using microcontact printed lipophilic self-assembled monolayers, in such a way as to retain their capacity to support biological functionality. Impedance spectroscopy, surface plasmon resonance, and atomic force microscopy are used to monitor the formation and investigate the properties of the supported bilayers. In addition, we show that the antibiotic peptide gramicidin and the ionophore valinomycin exhibit the expected ion selectivity. Finally, scanning force microscopy measurements show surface friction changes following bilayer formation. Chemically modified tips were used to obtain information about both the energy of the surface (hydrophobic/hydrophilic nature) and the mechanical properties of the surface.