Mechanical studies of hydrogel encapsulated membranes

2006 ◽  
Vol 926 ◽  
Author(s):  
Tae-Joon Jeon ◽  
Noah Malmstadt ◽  
Jacob Schmidt
Keyword(s):  
Lipid Bilayer ◽  
Lipid Membranes ◽  
Mechanical Stability ◽  
Electrical Measurement ◽  
Optical Measurements ◽  
Single Channels ◽  
Lipid Bilayer Membranes ◽  
Free Standing ◽  
Intimate Contact ◽  
High Throughput Drug Screening

ABSTRACTWe have encapsulated lipid bilayer membranes within a polyethylene glycol dimethacrylate hydrogel (PEG-DMA). These hydrogel encapsulated membranes (HEMs) are significantly longer-lived and more mechanically stable than traditional lipid membranes. Over 50 attempts, HEMs usually remained intact for over 48 hours, and some lasted up to 5 days. The electrical characteristics of the HEMs were consistently stable over this period of time. The approximate thickness of the HEM was measured to be 4.7±0.5 nm (n=25), consistent with a lipid bilayer. The resistance of the HEM remained over 10 GΩ over the period of electrical measurement. Simultaneous electrical and optical measurements showed that HEMs have unusual mechanical stability, whereas free-standing lipid membranes are typically susceptible to mechanical perturbation. The HEMs could withstand much greater applied pressures than unsupported membranes. In situ electrical and optical monitoring of the HEMs showed that the gel made intimate contact with the membrane, suggesting that direct mechanical support of the bilayer is the mechanism of membrane stabilization. Single channels of alpha-hemolysin, were incorporated into HEMs and continuously measured for over 4 days. Finally, combination of the HEM with an automated membrane microfluidic formation process is proposed as a prototype platform for high throughput drug screening or small molecule sensing.

scholarly journals Monazomycin-induced single channels. I. Characterization of the elementary conductance events.

1982 ◽  
Vol 80 (3) ◽  
pp. 403-426 ◽  
Author(s):  
O S Andersen ◽  
R U Muller
Keyword(s):  
Lipid Bilayer ◽  
Single Channels ◽  
Lipid Bilayer Membranes ◽  
Current Voltage ◽  
Voltage Dependent ◽  
Conductance Changes ◽  
Current Voltage Characteristics ◽  
The Individual ◽  
Positively Charged

Monazomycin (a positively charged, polyene-like antibiotic) induces voltage-dependent conductance changes in lipid bilayer membranes when added to one of the bathing solutions. These conductance changes have generally been attributed to the existence of channels spanning the membrane. In this article we characterize the behavior of the individual conductance events observed when adding small amounts of monazomycin to one side of a lipid bilayer. We find that there are several apparent channel types with one or sometimes two amplitudes predominating. We find further that these fairly similar amplitudes represent two different states of the same fundamental channel entity, presumed to be the monazomycin channel. The current-voltage characteristics of these channels are weakly hyperbolic functions of applied potential. The average lifetimes are essentially voltage independent (between 50 and 400 mV). The average channel intervals, on the other hand, can be strongly voltage dependent, and we can show that the time-averaged conductance of a membrane is proportional to the average channel frequency.

scholarly journals Quantitative Mapping of Free-Standing Lipid Membranes on Nano-Porous Mica Substrates

2018 ◽  
Author(s):  
Luca Costa ◽  
Adrian Carretero-Genevrier ◽  
Etienne Ferrain ◽  
Pierre-Emmanuel Milhiet ◽  
Laura Picas
Keyword(s):  
Lipid Membranes ◽  
Mechanical Response ◽  
Mechanical Stability ◽  
Biological Membranes ◽  
Chemical Properties ◽  
Elastic Response ◽  
Free Standing ◽  
Bending Modulus ◽  
Quantitative Mapping ◽  
Cell Adhesion And Migration

ABSTRACTThe physic-chemistry of biological membranes is at the origin of fundamental cellular functions such as vesicle trafficking, cell adhesion and migration1-3. Because most of intracellular shapes and local demixing of membranes take place in the nanometer scale, AFM becomes an extremely powerful technique to assess the properties of these biological membranes. Porous substrates provide an elegant strategy to avoid the conundrum of placing soft and thin biomembranes on hard substrates for AFM studies, although the surface chemistry make the actual substrates rather challenging setups. Here, we have engineered porous systems on the most widely used substrate in AFM, mica muscovite, with tunable pore sizes from some tens to few hundreds nanometers for biological applications. We show that free-standing bilayers on nano-porous can be obtained by using well-established vesicle spreading methods and that they display equivalent nano-mechanical stability and phsyco-chemical properties to that of membranes on conventional mica supports. By reducing the pore radius < 40 nm and limiting the contribution of membrane tension to the elastic response of free-standing membranes we estimate a bending modulus of 18 kbT and 73 kbT for DOPC and DPPC bilayers, respectively. The quantitative mapping of suspended membranes shows a different mechanical response at the pore rims, which is more pronounced for DPPC and suggest a different lipid ordering. We find that the combination of membrane bending and the different lipid packing at the edges of pores shapes the curvature of free-standing membranes on pores in the range of few tens of nm.

Amphiphobic Septa Enhance the Mechanical Stability of Free-Standing Bilayer Lipid Membranes

Langmuir ◽  
2018 ◽  
Vol 34 (19) ◽  
pp. 5615-5622 ◽  
Author(s):  
Daichi Yamaura ◽  
Daisuke Tadaki ◽  
Shun Araki ◽  
Miyu Yoshida ◽  
Kohei Arata ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Mechanical Stability ◽  
Bilayer Lipid Membranes ◽  
Free Standing ◽  
Bilayer Lipid

scholarly journals Stable Free-Standing Lipid Bilayer Membranes in Norland Optical Adhesive 81 Microchannels

2016 ◽  
Vol 88 (15) ◽  
pp. 7466-7470 ◽  
Author(s):  
Victor Marin ◽  
Roland Kieffer ◽  
Raymond Padmos ◽  
Marie-Eve Aubin-Tam
Keyword(s):  
Lipid Bilayer ◽  
Lipid Bilayer Membranes ◽  
Free Standing ◽  
Bilayer Membranes ◽  
Optical Adhesive

scholarly journals Discrete Conductance Fluctuations in Lipid Bilayer Protein Membranes

1969 ◽  
Vol 53 (6) ◽  
pp. 741-757 ◽  
Author(s):  
R. C. Bean ◽  
W. C. Shepherd ◽  
H. Chan ◽  
Joellen Eichner
Keyword(s):  
Lipid Bilayer ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Membrane Lipids ◽  
Initial Reaction ◽  
Lipid Bilayer Membranes ◽  
Conductance Fluctuations ◽  
Excitable Membranes ◽  
Conductance States ◽  
High Conductance

Discrete fluctuations in conductance of lipid bilayer membranes may be observed during the initial stages of membrane interaction with EIM ("excitability inducing material"), during destruction of the EIM conductance by proteolysis, and during the potential-dependent transitions between low and high conductance states in the "excitable" membranes. The discrete conductance steps observed during the initial reaction of EIM with the lipid membranes are remarkably uniform, even in membranes of widely varying lipid composition. They range only from 2 to 6 x 10-10 ohm-1 and average 4 x 10-10 ohm-1. Steps found during destruction of the EIM conductance by proteolysis are somewhat smaller. The transition between high conductance and low conductance states may involve steps as small as 0.5 x 10-10 ohm-1. These phenomena are consistent with the formation of a stable protein bridge across the lipid membrane to provide a polar channel for the transport of cations. T6he uniform conductance fluctuations observed during the formation of these macromolecular channels may indicate that the ions in a conductive channel, in its open state, are largely protected from the influence of the polar groups of the membrane lipids. Potential-dependent changes in conductance may be due to configurational or positional changes in the protein channel. Differences in lipid-lipid and lipid-macromolecule interactions may account for the variations in switching kinetics in various membrane systems.

Mechanically Stable Free-Standing Bilayer Lipid Membranes in Microfabricated Silicon Chips

2012 ◽  
Vol 1415 ◽  
Author(s):  
Azusa Oshima ◽  
Ayumi Hirano-Iwata ◽  
Yasuo Kimura ◽  
Michio Niwano
Keyword(s):  
Lipid Membranes ◽  
Mechanical Stability ◽  
Electric Properties ◽  
Bilayer Lipid Membranes ◽  
Dramatic Improvement ◽  
Free Standing ◽  
High Throughput Analysis ◽  
Bilayer Lipid ◽  
Gramicidin Channel ◽  
Insulator Layers

ABSTRACTIn this paper, we will discuss our recent approaches for improving the mechanical stability of free-standing bilayer lipid membranes (BLMs) by combining with BLM formation and microfabrication techniques. BLMs were prepared across a microaperture fabricated in a silicon (Si) chip and their mechanical stability and electric properties were investigated. BLMs suspended in a thin Si3N4 septum showed a dramatic improvement of BLM stability. The BLMs were resistant to voltage of ±1 V and the membrane lifetime was 15- ~40 h with and without incorporated channels. The membrane containing gramicidin channel exhibited tolerance to repetitive solution exchanges. At first, electric properties of the BLMs, such as noise level and current transient, were necessary to be improved. However, after coating the chip with insulator layers of Teflon and SiO2, total chip capacitance was reduced, leading to noise reduction (1-2 pA in peak-to-peak after low-pass filtering at 1 kHz) and elimination of current transients (< 0.5 ms). Since the vicinity of the aperture edge was remained uncoated, the BLMs formed in the Si chips still showed high mechanical stability after the insulator coatings. The mechanically stable BLMs having electric properties suitable for recording activities of biological channels will open up a variety of applications including high-throughput analysis of ion-channel proteins.

Miniaturized Silicon Apertures for Lipid Bilayer Reconstitution Experiments

2009 ◽  
Vol 1191 ◽  
Author(s):  
Michael Goryll ◽  
Nipun Chaplot
Keyword(s):  
Ion Channels ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
High Throughput ◽  
Drug Screening ◽  
Lab On A Chip ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
High Throughput Drug Screening ◽  
Micron Size

AbstractIon channels reconstituted into lipid bilayer membranes can be used as a very sensitive and selective platform for high-throughput drug screening applications. In order to employ suspended lipid bilayer membranes for these experiments in form of a “lab-on-a-chip” configuration, a robust and affordable platform is required. In our study, we investigated the feasibility of hosting lipid bilayer membranes across micron-size apertures ranging from 5 μm – 50 μm in silicon. On these substrates, lipid bilayers were formed and characterized concerning their seal resistance, capacitance and breakdown voltage. Seal resistance values of up to 60 GΩ could be achieved repeatedly on these substrates.

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