The design of molecular sensing interfaces with lipid-bilayer assemblies

Tuning the Probe-Bilayer Architecture of Silver Nanoneedle-based Ion Channel Probes

Ion channel probes, as one of the ion channel platforms, provide an appealing opportunity to perform localized detection with a high precision level. These probes come basically in two classes: glass and metal. While the glass-based probes showed the potential to be employed for molecular sensing and chemical imaging, these probes still suffer from limited resolution and lack of control over protein insertion. On the other hand, metal-based nanoneedle probes (gold and silver) have been recently developed to allow reducing probe dimensions to the nanoscale geometry. More specifically, silver probes are preferable owing to their ability to mitigate the channel current decay observed with gold probes and provide a stable DC channel current. However, there are still some challenges related to the probe design and bilayer curvature that render such probes insensitive to small changes in the tip-substrate distance. Herein, we introduce two main pathways to control the probe-bilayer architecture; the first is by altering the probe shape and geometry during the fabrication process of silver probes. The second pathway is by altering the surface characteristics of the silver probe via an electrophoretic deposition process. Our findings reveal that varying the electrochemical etching parameters results in different probe geometries and producing sharper tips with a 2-fold diameter reduction. In addition, the electrophoretic deposition of a cathodic paint on the silver nanoneedle surface led to a miniaturized exposed silver tip that enables the formation of a confined bilayer. We further investigated the characteristics of bilayers supported on both the sharper nanoneedles and the HSR-coated silver probes produced by controlling the etching conditions and electrodeposition process, respectively. We believe this work paves the way to rationally design silver nanoneedle ion channel probes, which are well suited for localized molecular sensing and chemical imaging.

Assembly of Cell-Free Synthesized Ion Channel Molecules in Artificial Lipid Bilayer Observed by Atomic Force Microscopy

Artificial lipid bilayer systems, such as vesicles, black membranes, and supported lipid bilayers (SLBs), are valuable platforms for studying ion channels at the molecular level. The reconstitution of the ion channels in an active form is a crucial process in studies using artificial lipid bilayer systems. In this study, we investigated the assembly of the human ether-a-go-go-related gene (hERG) channel prepared in a cell-free synthesis system. AFM topographies revealed the presence of protrusions with a uniform size in the entire SLB that was prepared with the proteoliposomes (PLs) incorporating the cell-free-synthesized hERG channel. We attributed the protrusions to hERG channel monomers, taking into consideration the AFM tip size, and identified assembled structures of the monomer that exhibited dimeric, trimeric, and tetrameric-like arrangements. We observed molecular images of the functional hERG channel reconstituted in a lipid bilayer membrane using AFM and quantitatively evaluated the association state of the cell-free synthesized hERG channel.

Maintaining Single-Channel Recordings on a Silver Nanoneedle through Probe Design and Feedback Tip Positioning Control

Ion channel proteins showed great promise in the field of nanopore sensing and molecular flux imaging applications due to the atomic-level precision of the pore size and a high signal-to-noise ratio. More specifically, ion channel probes, where the protein channels are integrated at the end of a solid probe, can achieve highly localized detection. Metal probe materials such as gold and silver have been developed to support lipid bilayers and enable the use of smaller probes, or nanoneedles, compared to more traditional glass micropipette ion channel probes. Silver probes are preferable because they support sustained DC stable channel current due to the AgCl layer formed around the tip during the fabrication process. However, one of the current challenges in ion channel measurements is maintaining a single-channel recording. Multiple protein insertions complicate data analysis and destabilize the bilayer. Herein, we combine the promising probe material (Ag/AgCl) with an approach based on current feedback-controlled tip positioning to maintain long-term single-channel recordings for up to 3 h. We develop a hybrid positioning control system, where the channel current is used as feedback to control the vertical movement of the silver tip and, subsequently, control the number of protein channels inserted in the lipid membrane. Our findings reveal that the area of the lipid bilayer decreases with moving the silver tip up (i.e., decreasing the displacement in the z-direction). By reducing the bilayer area around the fine silver tip, we minimize the probability of multiple insertions and remove unwanted proteins. In addition, we characterize the effect of lipid properties such as fluidity on the lipid membrane area. We believe that the use of silver nanoneedles, which enables DC stable channel current, coupled with the developed tip displacement mechanism will offer more opportunities to employ these probes for chemical imaging and mapping different surfaces.

Biochemistry strategies for label-free optical sensor biofunctionalization: advances towards real applicability

Label-free biosensors, and especially those based on optical transducers like plasmonic or silicon photonic systems, have positioned themselves as potential alternatives for rapid and highly sensitive clinical diagnostics, on-site environmental monitoring, and for quality control in foods or other industrial applications, among others. However, most of the biosensor technology has not yet been transferred and implemented in commercial products. Among the several causes behind that, a major challenge is the lack of standardized protocols for sensor biofunctionalization. In this review, we summarize the most common methodologies for sensor surface chemical modification and bioreceptor immobilization, discussing their advantages and limitations in terms of analytical sensitivity and selectivity, reproducibility, and versatility. Special focus is placed on the suggestions of innovative strategies towards antifouling and biomimetic functional coatings to boost the applicability and reliability of optical biosensors in clinics and biomedicine. Finally, a brief overview of research directions in the area of device integration, automation, and multiplexing will give a glimpse of the future perspectives for label-free optical biosensors.

Silver Nanoneedle Probes Enable Sustained DC Current, Single-Channel Resistive Pulse Nanopore Sensing

Resistive pulse sensing using ion channel proteins (biological nanopores) has been evolving as a single-molecule approach to detect small biomolecules owing to atomically precise pore size reproducibility, high signal-to-noise ratio, and molecular selectivity. The incorporation of biological nanopores in sensing platforms requires a stable lipid membrane that can be formed by a variety of methods such as the painting method and droplet-based techniques. However, these methods are limited by the fragility of the unsupported bilayer or the need for specific microdevices. Electrode-supported bilayers, in which a metal electrode is used as a support structure, have been recently developed using a fine gold nanoneedle. We previously described the utility of the gold nanoneedle-supported ion channel probe to detect small molecules with high spatial resolution; however, it exhibited a channel current decay over time, which affected the binding frequency of the target molecule to the protein pore as well. Here, we introduce a silver nanoneedle probe to support the lipid bilayer formation and ion channel measurements. The silver nanoneedle mitigates the current decay observed on gold electrodes and produces stable DC channel currents. Our findings propose the formation of a AgCl layer creating a nonpolarizable electrode. The new nanoneedle is successfully applied for single-molecule detection of sulfonated β-cyclodextrin (S₇βCD) using αHL as a test bed protein. We believe that this new silver nanoneedle platform has great potential given the relative ease of lipid bilayer formation and stable open channel currents.

Pair of Residue Substitutions at the Outer Mouth of the Channel Pore Act as Inputs for a Boolean Logic "OR" Gate Based on the Glycine Receptor

The glycine receptor (GlyR) is a ligand-activated chloride channel, whose mutations are the major cause of hereditary hyperekplexia. The hyperekplexia-causing R271Q mutation, which is located at the extracellular outer mouth of the channel pore, dramatically impairs the GlyR function manifesting a reduced sensitivity toward glycine. This study reports that a second mutation, S273D, rescues the function of the R271Q GlyR to that of the wild-type (WT) GlyR. Surprisingly, the S273D mutation, when introduced to the WT GlyR, does not further increase the receptor function. In other words, the compromised function of the 271Q 273S GlyR (i.e., the R271Q GlyR) can be rescued to WT levels by the introduction of either, or both, of the Q271R and S273D substitutions. From the perspective of Boolean logic gates, the Q271R and S273D substitutions act as inputs for an OR gate based on the GlyR. Further experiments revealed that the negative-charge carried by the 273 residue is essential for the expression of the OR gate and that the expression of the OR gate is residue-position-specific. In addition, mechanistic investigation implied that the 273 residue influences the 271 residue, which might underpin the unique nonadditive OR gate relationship between these two residues. Such an ion-channel-based OR gate, expressing output in the form of electrical current, could potentially be developed to digitally manipulate neuronal activity.

Considerations of Antibody Geometric Constraints on NK Cell Antibody Dependent Cellular Cytotoxicity

It has been well-established that antibody isotype, glycosylation, and epitope all play roles in the process of antibody dependent cellular cytotoxicity (ADCC). For natural killer (NK) cells, these phenotypes are linked to cellular activation through interaction with the IgG receptor FcγRIIIa, a single pass transmembrane receptor that participates in cytoplasmic signaling complexes. Therefore, it has been hypothesized that there may be underlying spatial and geometric principles that guide proper assembly of an activation complex within the NK cell immune synapse. Further, synergy of antibody phenotypic properties as well as allosteric changes upon antigen binding may also play an as-of-yet unknown role in ADCC. Understanding these facets, however, remains hampered by difficulties associated with studying immune synapse dynamics using classical approaches. In this review, I will discuss relevant NK cell biology related to ADCC, including the structural biology of Fc gamma receptors, and how the dynamics of the NK cell immune synapse are being studied using innovative microscopy techniques. I will provide examples from the literature demonstrating the effects of spatial and geometric constraints on the T cell receptor complex and how this relates to intracellular signaling and the molecular nature of lymphocyte activation complexes, including those of NK cells. Finally, I will examine how the integration of high-throughput and "omics" technologies will influence basic NK cell biology research moving forward. Overall, the goal of this review is to lay a basis for understanding the development of drugs and therapeutic antibodies aimed at augmenting appropriate NK cell ADCC activity in patients being treated for a wide range of illnesses.

Recessed Ag/AgCl Microelectrode-Supported Lipid Bilayer for Nanopore Sensing

Biological nanopores reconstituted into supported lipid bilayer membranes are widely used as a platform for stochastic nanopore sensing with the ability to detect single molecules including, for example, single-stranded DNA (ssDNA) and miRNA. A main thrust in this area of research has been to improve overall bilayer stability and ease of measurements. These improvements are achieved through a variety of clever strategies including droplet-based techniques; however, they typically require specific microfabrication techniques to prepare devices or special manipulation techniques for microdroplets. Here, we describe a new method to prepare lipid bilayers using a recessed-in-glass Ag/AgCl microelectrode as a support structure. The lipid bilayer is formed at the tip of the microelectrode by immersing the microelectrode into a layered bath solution consisting of an oil/lipid mixture and an aqueous electrolyte solution. In this paper, we demonstrate this stable, supported lipid bilayer structure for channel current measurements of pore-forming toxins and single-molecule detection of ssDNA. This Ag/AgCl-supported lipid bilayer can potentially be widely adopted as a lipid membrane platform for nanopore sensing because of its simple and easy procedure needed to prepare lipid bilayers.

Formation of Cell Membrane Component Domains in Artificial Lipid Bilayer

The lipid bilayer environment around membrane proteins strongly affects their structure and functions. Here, we aimed to study the fusion of proteoliposomes (PLs) derived from cultured cells with an artificial lipid bilayer membrane and the distribution of the PL components after the fusion. PLs, which were extracted as a crude membrane fraction from Chinese hamster ovary (CHO) cells, formed isolated domains in a supported lipid bilayer (SLB), comprising phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cholesterol (Chol), after the fusion. Observation with a fluorescence microscope and an atomic force microscope showed that the membrane fusion occurred selectively at microdomains in the PC + PE + Chol-SLB, and that almost all the components of the PL were retained in the domain. PLs derived from human embryonic kidney 293 (HEK) cells also formed isolated domains in the PC + PE + Chol-SLB, but their fusion kinetics was different from that of the CHO-PLs. We attempted to explain the mechanism of the PL-SLB fusion and the difference between CHO- and HEK-PLs, based on a kinetic model. The domains that contained the whole cell membrane components provided environments similar to that of natural cell membranes, and were thus effective for studying membrane proteins using artificial lipid bilayer membranes.

Tuning biomimetic membrane barrier properties by hydrocarbon, cholesterol and polymeric additives

The barrier properties of cellular membranes are increasingly attracting attention as a source of inspiration for designing biomimetic membranes. The broad range of potential technological applications makes the use of lipid and lately also polymeric materials a popular choice for constructing biomimetic membranes, where the barrier properties can be controlled by the composition of the membrane constituent elements. Here we investigate the membrane properties reported by the light-induced proton pumping activity of bacteriorhodopsin (bR) reconstituted in three vesicle systems of different membrane composition. Specifically we quantify how the resulting proton influx and efflux rates are influenced by the membrane composition using a variety of membrane modulators. We demonstrate that by adding hydrocarbons to vesicles with reconstituted bR formed from asolectin lipids the resulting transmembrane proton fluxes changes proportional to the carbon chain length when compared against control. We observe a similar proportionality in single-component 1,2-Dioleoyl-sn-glycero-3-phosphocholine model membranes when using cholesterol. Lastly we investigate the effects of adding the amphiphilic di-block co-polymer polybutadiene-polyethyleneoxide (PB₁₂-PEO₁₀) to phospholipid membranes formed from 1,2-Dioleoyl-sn-glycero-3-phosphocholine, 1,2-Dioleoyl-sn-glycero-3-phosphatidylethanolamine, and 1,2-Dioleoyl-sn-glycero-3-phosphatidylserine. The proton pumping activity of bR (measured as a change in extra-vesicular pH) in mixed lipid/PB₁₂-PEO₁₀ lipid systems is up to six-fold higher compared to that observed for bR containing vesicles made from PB₁₂-PEO₁₀ alone. Interestingly, bR inserts with apparent opposite orientation in pure PB₁₂-PEO₁₀ vesicles as compared to pure lipid vesicles. Addition of equimolar amounts of lipids to PB₁₂-PEO₁₀ results in bR orientation similar to that observed for pure lipids. In conclusion our results show how the barrier properties of the membranes can be controlled by the composition of the membrane. In particular the use of mixed lipid-polymer systems may pave the way for constructing biomimetic membranes tailored for optimal properties in various applications including drug delivery systems, biosensors and energy conservation technology.

Transmembrane Signaling with Lipid-Bilayer Assemblies as a Platform for Channel-Based Biosensing

Artificial and natural lipid membranes that elicit transmembrane signaling is are useful as a platform for channel-based biosensing. In this account we summarize our research on the design of transmembrane signaling associated with lipid bilayer membranes containing nanopore-forming compounds. Channel-forming compounds, such as receptor ion-channels, channel-forming peptides and synthetic channels, are embedded in planar and spherical bilayer lipid membranes to develop highly sensitive and selective biosensing methods for a variety of analytes. The membrane-bound receptor approach is useful for introducing receptor sites on both planar and spherical bilayer lipid membranes. Natural receptors in biomembranes are also used for designing of biosensing methods.

Artificial Lipid Membranes: Past, Present, and Future

The multifaceted role of biological membranes prompted early the development of artificial lipid-based models with a primary view of reconstituting the natural functions in vitro so as to study and exploit chemoreception for sensor engineering. Over the years, a fair amount of knowledge on the artificial lipid membranes, as both, suspended or supported lipid films and liposomes, has been disseminated and has helped to diversify and expand initial scopes. Artificial lipid membranes can be constructed by several methods, stabilized by various means, functionalized in a variety of ways, experimented upon intensively, and broadly utilized in sensor development, drug testing, drug discovery or as molecular tools and research probes for elucidating the mechanics and the mechanisms of biological membranes. This paper reviews the state-of-the-art, discusses the diversity of applications, and presents future perspectives. The newly-introduced field of artificial cells further broadens the applicability of artificial membranes in studying the evolution of life.

Reconstitution of Human Ion Channels into Solvent-free Lipid Bilayers Enhanced by Centrifugal Forces

Artificially formed bilayer lipid membranes (BLMs) provide well-defined systems for functional analyses of various membrane proteins, including ion channels. However, difficulties associated with the integration of membrane proteins into BLMs limit the experimental efficiency and usefulness of such BLM reconstitution systems. Here, we report on the use of centrifugation to more efficiently reconstitute human ion channels in solvent-free BLMs. The method improves the probability of membrane fusion. Membrane vesicles containing the human ether-a-go-go-related gene (hERG) channel, the human cardiac sodium channel (Nav1.5), and the human GABAA receptor (GABAAR) channel were formed, and the functional reconstitution of the channels into BLMs via vesicle fusion was investigated. Ion channel currents were recorded in 67% of the BLMs that were centrifuged with membrane vesicles under appropriate centrifugal conditions (14-55 × g). The characteristic channel properties were retained for hERG, Nav1.5, and GABAAR channels after centrifugal incorporation into the BLMs. A comparison of the centrifugal force with reported values for the fusion force revealed that a centrifugal enhancement in vesicle fusion was attained, not by accelerating the fusion process but by accelerating the delivery of membrane vesicles to the surface of the BLMs, which led to an increase in the number of membrane vesicles that were available for fusion. Our method for enhancing the probability of vesicle fusion promises to dramatically increase the experimental efficiency of BLM reconstitution systems, leading to the realization of a BLM-based, high-throughput platform for functional assays of various membrane proteins.

Enhanced Temporal Resolution with Ion Channel-Functionalized Sensors Using a Conductance-Based Measurement Protocol

The binding of a target analyte to an ion channel (IC), which is readily detected electrochemically in a label-free manner with single-molecule selectivity and specificity, has generated widespread interest in using natural and engineered ICs as transducers in biosensing platforms. To date, the majority of developments in IC-functionalized sensing have focused on IC selectivity or sensitivity or development of suitable membrane environments and aperture geometries. Comparatively little work has addressed analytical performance criteria, particularly criteria required for temporal measurements of dynamic processes. We report a measurement protocol suitable for rapid, time-resolved monitoring (≤30 ms) of IC-modulated membrane conductance. Key features of this protocol include the reduction of membrane area and the use of small voltage steps (10 mV) and short duration voltage pulses (10 ms), which have the net effect of reducing the capacitive charging and decreasing the time required to achieve steady state currents. Application of a conductance protocol employing three sequential, 10 ms voltage steps (-10 mV, -20 mV, -30 mV) in an alternating, pyramid-like arrangement enabled sampling of membrane conductance every 30 ms. Using this protocol, dynamic IC measurements on black lipid membranes (BLMs) functionalized with gramicidin A were conducted using a fast perfusion system. BLM conductance decreased by 76 ± 7.5% within 30 ms of switching from solutions containing 0 to 1 M Ca2+, which demonstrates the feasibility of using this approach to monitor rapid, dynamic chemical processes. Rapid conductance measurements will be broadly applicable to IC-based sensors that undergo analyte-specific gating.

Lateral Diffusion and Molecular Interaction in a Bilayer Membrane Consisting of Partially Fluorinated Phospholipids

Fluorinated lipids and surfactants are attractive biomimetic materials for the extraction and reorganization of membrane proteins because of the biological inertness of fluorocarbons. We investigated the fundamental physical properties of a partially fluorinated phospholipid (F4-DMPC), such as phase transition, area thermal expansion, and lateral lipid diffusion, to evaluate the intermolecular interaction of F4-DMPC in the hydrophobic region quantitatively on the basis of free-volume theory. Fluorescence microscope observation of the supported lipid bilayer (SLB) of F4-DMPC showed that the phase transition between the liquid crystalline and gel phases occurred at 5 °C and that the area thermal expansion coefficient was independent of the temperature near the phase transition temperature. We performed a single particle tracking of the F4-DMPC-SLB on a SiO₂/Si substrate, to measure the diffusion coefficient and its temperature dependence. The apparent activation energy (E'_a) of lateral lipid diffusion, which is an indicator of intermolecular interaction, was 39.1 kJ/mol for F4-DMPC, and 48.2 kJ/mol for a nonfluorinated 1,2-dioleoyl-sn-glycero-3-phosphocholine as a control. The difference of 9 kJ/mol in E'_a was significant compared with the difference due to the acyl chain species among nonfluorinated phosphatidylcholine and also that caused by the addition of cholesterol and alcohol in the bilayer membranes. We quantitatively evaluated the attenuation of intermolecular interaction, which results from the competition between the dipole-induced packing effect and steric effect at the fluorocarbon segment in F4-DMPC.

Nanopore formation process in artificial cell membrane induced by plasma-generated reactive oxygen species

We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies.

Measurement of membrane tension of free standing lipid bilayers via laser-induced surface deformation spectroscopy

Non-invasive measurement of the membrane tension of free-standing black lipid membranes (BLMs), with sensitivity on the order of μN m(-1), was achieved using laser-induced surface deformation (LISD) spectroscopy. A BLM was vertically formed via the folding method and aqueous phases with different refractive indices were added on each side in order to induce radiation pressure by a laser beam. The dynamic response of the deformed BLMs was measured under periodic intensity modulation and their tensions could be estimated. The dependence of membrane tension on the cholesterol concentration of BLMs composed of phosphatidylcholine and phosphatidylethanolamine was investigated, with the membrane tension increasing from 1.3 μN m(-1) to 68.1 μN m(-1) when the cholesterol concentration increased from zero to 33%. These tension values are much smaller than some of those previously reported, because this method does not suppress membrane fluctuation unlike other conventional methods. Our LISD system can be a promising tool for the measurement of membrane tension in BLMs.

Pore-forming compounds as signal transduction elements for highly sensitive biosensing

Pore-forming compounds are attracting much attention due to the signal transduction ability for the development of highly sensitive biosensing. In this review, we describe an overview of the recent advances made by our group in the design of molecular sensing interfaces of spherical and planar lipid bilayers and natural bilayers. The potential uses of pore-forming compounds, such as gramicidin and MCM-41, in lipid bilayers and natural glutamate receptor channels in biomembrane are presented.

Miniaturised technologies for the development of artificial lipid bilayer systems

Artificially reproducing cellular environments is a key aim of synthetic biology, which has the potential to greatly enhance our understanding of cellular mechanisms. Microfluidic and lab-on-a-chip (LOC) techniques, which enable the controlled handling of sub-microlitre volumes of fluids in an automated and high-throughput manner, can play a major role in achieving this by offering alternative and powerful methodologies in an on-chip format. Such techniques have been successfully employed over the last twenty years to provide innovative solutions for chemical analysis and cell-, molecular- and synthetic- biology. In the context of the latter, the formation of artificial cell membranes (or artificial lipid bilayers) that incorporate membrane proteins within miniaturised LOC architectures offers huge potential for the development of highly sensitive molecular sensors and drug screening applications. The aim of this review is to give a comprehensive and critical overview of the field of microsystems for creating and exploiting artificial lipid bilayers. Advantages and limitations of three of the most popular approaches, namely suspended, supported and droplet-based lipid bilayers, are discussed. Examples are reported that show how artificial cell membrane microsystems, by combining together biological procedures and engineering techniques, can provide novel methodologies for basic biological and biophysical research and for the development of biotechnology tools.

Free-standing lipid bilayers in silicon chips-membrane stabilization based on microfabricated apertures with a nanometer-scale smoothness

In the present study, we propose a method for preparing stable free-standing bilayer lipid membranes (BLMs). The BLMs were prepared in a microfabricated aperture with a smoothly tapered edge, which was prepared in a nanometer-thick Si(3)N(4) septum by the wet etching method. Owing to this structure, the stress on lipid bilayers at the contact with the septum was minimized, leading to remarkable membrane stability. The BLMs were not broken by applying a constant voltage of +/-1 V. The membrane lifetime was 15-45 h with and without an incorporated gramicidin channel. Gramicidin single-channel currents were recorded from the same BLM preparation when the aqueous solutions surrounding the BLM were repeatedly exchanged, demonstrating the tolerance of the present BLM to repetitive solution exchanges. Such stable membranes enable analysis of channel functions under various solution conditions from the same BLM, which will open up a variety of applications including a high throughput drug screening for ion channels.

Rapid fabrication of Teflon micropores for artificial lipid bilayer formation

A number of recent studies have dealt with the development of biosensors using single-channel recording with an artificial lipid bilayer. However, the fragility of these bilayers and current noise present serious problems in their application towards biosensor development. To address this problem, many experimental investigations employing micropores in the formation of lipid bilayers have been reported. In this work, we present a method for the fabrication of micropores using commercially available low-melting Teflon film and a heated tip. This method allowed for the rapid (in a few seconds) and reproducible fabrication of micropores 2-3 microm in diameter. We employed a single-channel recording using a gramicidin channel and confirmed that the bilayer membrane can form on micropores by the painting method. The bilayer formed is stable under high voltage (+1000mV). Fabricated micropores possess a conical shape with sharp edges, features which facilitated the formation of artificial lipid bilayers which could be utilized for low-noise and high voltage recording due to decreased access resistance and increased bilayer stability. These advantages promise to improve the performance of artificial lipid bilayers when employed in the development of flexible biosensors.