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6 results on '"TBLM"'

1. Modified tethered bilayer lipid membranes for detection of pathogenic bacterial toxins and characterization of ion channels

Author

Thet, Naing Tun and Jenkins, Andrew

Subjects
540, Pathogenic bacteria, alpha hemolysin, phospholipase, nanopores, TBLM
Abstract

Pathogenic bacteria secrete various virulence factors as their biochemical weapons to gain access to and destroy the target cells. They can directly interact with the outer lipid bilayer membrane of eukaryotic cells, inducing the premature cell death by either apoptosis or necrosis. Such virulence factors account for much of the toxic actions associated with bacterial infection; therefore the detection of such proteins could provide a methodology for sensing/detection of pathogenic bacteria in, for example, food or human tissue. Detection and identification of pathogenic bacteria by conventional methods such as plating and counting in laboratory is expensive and time consuming. With growing concerns over emergence and re-emergence of pathogenic bacteria with high resistant to current antibiotics, there is a potential need for effective detection of pathogenic toxins invitro. On the other hand, artificially prepared lipid bilayer membrane on planar metallic surfaces provides the cell membrane mimics which are extremely useful in exploring the cellular functions and processes at the molecular level. Therefore in this work, an application of planar tethered bilayer lipid membrane (pTBLM) as a biomimetic sensing platform for the detection of clinically important pathogens, Staphylococcus aureus and Pseudomonas aeruginosa via their secreted virulence factors was presented. Planar TBLM was modified by incorporation of cholesterol and detection of bacterial toxins at human body temperature was examined by impedance and surface plasmon resonance methods. The results of pathogenic bacterial toxin detection were compared with those of Escherichia coli (DH5α), the human gut normal flora with non-pathogenic strain, as a control. Additionally pTBLM was transferred onto single nanoporous Si3N4 membrane to enhance the toxin sensitivity and extend the lifetime for the possible realization of future membrane chips for ion channel characterizations and drug screenings. Then the single ion channel measurement was demonstrated with nanopore-suspended TBLM (Nano-psTBLM) using α-toxin of S. aureus. The results presented in this work therefore, may pave the more effective and efficient ways for future pathogenic bacterial detection in which the sensing mechanism was solely based on the nature of interactions as well as modes of action between bacterial toxins and artificial lipid bilayer membranes.

Published
2010

2. Validation of Cu toxicity to barley root elongation in soil with a Terrestrial Biotic Ligand Model developed from sand culture.

Author

Lin, Yanqing, Allen, Herbert E., and Di Toro, Dominic M.

Subjects
BARLEY, MICROBIOLOGY, PLANT roots, COPPER toxicity testing, SOIL microbiology, SOIL testing, PHYSIOLOGY
Abstract

Constants for a Terrestrial Biotic Ligand Model (TBLM) to predict the Cu toxicity to barley root elongation (RE) were developed from controlled sand culture experiments. These constants were used to predict RE in soil culture. The competition of H + , Ca 2+ , and Mg 2+ to Cu 2+ toxicity were studied individually and independently, and linear relationships between EC50 free Cu 2+ and H + , Ca 2+ , and Mg 2+ activities were found, meaning that the cations H + , Ca 2+ , and Mg 2+ will alleviate the toxicity of Cu 2+ in solutions. Toxicity accompanying increasing concentration of solution ions other than Cu 2+ was observed and modeled as an osmotic effect which improved soil culture toxicity prediction. The Root Mean Square Error (RMSE) of %RE and EC50 (50% effective concentration) for soil toxicity prediction using TBLM parameters developed from sand culture are 13.0 and 0.23 respectively, which are as good as that of 14.0 and 0.24 using parameters that developed from soil culture itself. A model including the activity at the root plasma membrane surface was tested and found not to provide improvement over the use of bulk solution activity to predict metal toxicity. TBLM parameters obtained from water solution culture were unable to accurately predict the EC50s in soils whereas the parameters obtained from sand culture were able to predict the toxicity in soils. Including the toxicity of CuOH + was found to improve the toxicity prediction slightly. [ABSTRACT FROM AUTHOR]

Published
2018
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3. Glycerol-based thiolipids for model membranes.

Author

Charkova, Tatjana, Kuodis, Zenonas, Matijoška, Algirdas, and Eicher-Lorka, Olegas

Subjects
*GLYCERIN, *LIPID synthesis, *ETHYLENE glycol, *THIOLS, *BILAYER lipid membranes, *DISULFIDES
Abstract

An efficient synthesis of two glycerol-based thiolipids containing a neutral and flexible tetraethylene glycol chain with thiol and cyclic disulfide anchors for attachment onto a gold support is reported. Both synthesized products showed the ability to form tethered bilayer membranes. [ABSTRACT FROM AUTHOR]

Published
2014

4. Functional characterization of PorB class II porin from Neisseria meningitidis using a tethered bilayer lipid membrane

Author

Jadhav, Sachin R., Zheng, Yi, Michael Garavito, R., and Mark Worden, R.

Subjects
*NEISSERIA meningitidis, *BILAYER lipid membranes, *VOLTAMMETRY, *IMPEDANCE spectroscopy
Abstract

Abstract: PorB class II from Neisseria meningitidis is a pore-forming, outer-membrane protein that can translocate to the host-cell membrane during Neisserial infections. This report describes development of tethered bilayer lipid membrane (tBLM) system to measure PorB conductance properties. The tBLM was fabricated by depositing a self-assembled monolayer of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) tethering lipid on a gold electrode and then using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes to deposit the upper tBLM leaflet. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to monitor tBLM formation and subsequent PorB incorporation. The highly insulating tBLM exhibited a membrane resistance and capacitance of 2.5MΩcm2 and 0.7μF/cm2, respectively. PorB was incorporated into the tBLM in an active conformation, as evidenced by its mediation of ion passage and the decrease in membrane impedance. After PorB incorporation, the membrane resistance decreased to 0.6MΩcm2. As expected, the PorB channel was found to be non-selective, allowing the transport of both cations and anions. Cyclic voltammetry indicated that ferricyanide ions can also pass through the pores. The PorB-containing biomimetic interface developed in this study could potentially be used to screen for compounds that modulate PorB activity. [Copyright &y& Elsevier]

Published
2008
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5. A tethered bilayer sensor containing alamethicin channels and its detection of amiloride based inhibitors

Author

Yin, Ping, Burns, Christopher J., Osman, Peter D.J., and Cornell, Bruce A.

Subjects
*BIOSENSORS, *PEPTIDES, *ION channels
Abstract

Alamethicin, a small transmembrane peptide, inserts into a tethered bilayer membrane (tBLM) to form ion channels, which we have investigated using electrical impedance spectroscopy. The number of channels formed is dependent on the incubation time, concentration of the alamethicin and the application of DC voltage. The properties of the ion channels when formed in tethered bilayers are similar to those for such channels assembled into black lipid membranes (BLMs). Furthermore, amiloride and certain analogs can inhibit the channel pores, formed in the tBLMs. The potency and concentration of the inhibitors can be determined by measuring the change of impedance. Our work illustrates the possibility of using a synthetic tBLM for the study of small peptide voltage dependent ion channels. A potential application of such a device is as a screening tool in drug discovery processes. [Copyright &y& Elsevier]

Published
2003
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6. Modified tethered bilayer lipid membranes for detection of pathogenic bacterial toxins and characterization of ion channels

Author

Thet, N.

Subjects
TBLM, Pathogenic bacteria, nanopores, alpha hemolysin, phospholipase
Abstract

Pathogenic bacteria secrete various virulence factors as their biochemical weapons to gain access to and destroy the target cells. They can directly interact with the outer lipid bilayer membrane of eukaryotic cells, inducing the premature cell death by either apoptosis or necrosis. Such virulence factors account for much of the toxic actions associated with bacterial infection; therefore the detection of such proteins could provide a methodology for sensing/detection of pathogenic bacteria in, for example, food or human tissue. Detection and identification of pathogenic bacteria by conventional methods such as plating and counting in laboratory is expensive and time consuming. With growing concerns over emergence and re-emergence of pathogenic bacteria with high resistant to current antibiotics, there is a potential need for effective detection of pathogenic toxins invitro. On the other hand, artificially prepared lipid bilayer membrane on planar metallic surfaces provides the cell membrane mimics which are extremely useful in exploring the cellular functions and processes at the molecular level. Therefore in this work, an application of planar tethered bilayer lipid membrane (pTBLM) as a biomimetic sensing platform for the detection of clinically important pathogens, Staphylococcus aureus and Pseudomonas aeruginosa via their secreted virulence factors was presented. Planar TBLM was modified by incorporation of cholesterol and detection of bacterial toxins at human body temperature was examined by impedance and surface plasmon resonance methods. The results of pathogenic bacterial toxin detection were compared with those of Escherichia coli (DH5α), the human gut normal flora with non-pathogenic strain, as a control. Additionally pTBLM was transferred onto single nanoporous Si3N4 membrane to enhance the toxin sensitivity and extend the lifetime for the possible realization of future membrane chips for ion channel characterizations and drug screenings. Then the single ion channel measurement was demonstrated with nanopore-suspended TBLM (Nano-psTBLM) using α-toxin of S. aureus. The results presented in this work therefore, may pave the more effective and efficient ways for future pathogenic bacterial detection in which the sensing mechanism was solely based on the nature of interactions as well as modes of action between bacterial toxins and artificial lipid bilayer membranes.

Published
2010

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