A5088074795- Lipid Membrane Structure and Behavior
- Nuclear Physics and Applications
- Bacterial Genetics and Biotechnology
- Surfactants and Colloidal Systems
- Mesoporous Materials and Catalysis
- Ion channel regulation and function
- Polymer Surface Interaction Studies
- Spectroscopy and Quantum Chemical Studies
- Force Microscopy Techniques and Applications
- Atomic and Subatomic Physics Research
- Diatoms and Algae Research
- Pickering emulsions and particle stabilization
- Nanopore and Nanochannel Transport Studies
- Bacteriophages and microbial interactions
- Proteins in Food Systems
- Marine and fisheries research
- Advanced Cellulose Research Studies
- Iron oxide chemistry and applications
- Protein Structure and Dynamics
- Advanced biosensing and bioanalysis techniques
- Electrostatics and Colloid Interactions
- Molecular Junctions and Nanostructures
- Supramolecular Self-Assembly in Materials
- Electron and X-Ray Spectroscopy Techniques
- Antibiotic Resistance in Bacteria
Australian Nuclear Science and Technology Organisation
2014-2023
University of Technology Sydney
2021-2023
University of Auckland
2021
MacDiarmid Institute for Advanced Materials and Nanotechnology
2021
Flinders University
2021
Utrecht University
2021
Maurice Wilkins Centre
2021
Lucas Research
2017-2020
The University of Texas at Austin
1997-2014
Science and Technology Facilities Council
2009-2012
The Gram-negative bacterial outer membrane (GNB-OM) is asymmetric in its lipid composition with a phospholipid-rich inner leaflet and an predominantly composed of lipopolysaccharides (LPS). LPS are polyanionic molecules, numerous phosphate groups present the A core oligosaccharide regions. repulsive forces due to accumulation negative charges screened bridged by divalent cations (Mg2+ Ca2+) that known be crucial for integrity OM. Indeed, chelation well-established method permeabilize...
The Gram-negative bacterial outer membrane (OM) is a complex and highly asymmetric biological barrier but the small size of bacteria has hindered advances in vivo examination dynamics. Thus, model OMs, amenable to physical study, are important sources data. Here, we present data from bilayers which emulate OM formed by simple two-step approach. were deposited on an SiO2 surface Langmuir-Blodgett deposition phosphatidylcholine as inner leaflet and, via Langmuir-Schaefer deposition, either...
Abstract Gram‐negative bacteria are an increasingly serious source of antibiotic‐resistant infections, partly owing to their characteristic protective envelope. This complex, 20 nm thick barrier includes a highly impermeable, asymmetric bilayer outer membrane (OM), which plays pivotal role in resisting antibacterial chemotherapy. Nevertheless, the OM molecular structure and its dynamics poorly understood because is difficult recreate or study vitro. The successful formation characterization...
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsTheme Sections 313:249-259 (2006) - doi:10.3354/meps313249 Trophic ecology of Sargassum-associated fishes in Gulf Mexico determined from stable isotopes and fatty acids Jay R. Rooker1,*, Jason P. Turner1,3, Scott A. Holt2 1Department Biology, Texas A&M University, 5007 Avenue U, Galveston, 77551, USA 2Department Science,...
Time of day was determined for spawning several species sciaenid fishes by examin~ng development stages eggs collected in estuarine and near-shore plankton samples.Estuarine samples were taken at different times night but newly spawned Cynoscion nebulosus Bairdiella chrysoura only during a period from just before to 3 or 4 hours after sunset.Sclaenops ocellatus Mentichirrhus sp.eggs Gulf Mexico samples, the morning, all contained tail-bud stage embryos, indicating evening these species.It is...
Understanding the electrostatic interactions between bacterial membranes and exogenous proteins is crucial to designing effective antimicrobial agents against Gram-negative bacteria. Here we study, using neutron reflecometry under multiple isotopic contrast conditions, role of uncharged sugar groups in outer core region lipopolysaccharide (LPS) protecting phosphate-rich inner from with proteins. Models asymmetric Gram negative membrane on silicon were prepared phopshatidylcholine (PC)...
Lipopolysaccharides (LPS) make up approximately 75% of the Gram-negative bacterial outer membrane (OM) surface, but because complexity molecule, there are very few model OMs that include LPS. The LPS molecule consists lipid A, which anchors within OM, a core polysaccharide region, and variable O-antigen chain. In this work we used RcLPS (consisting A plus first seven sugars polysaccharide) from rough strain Escherichia coli to form stable monolayers at air-liquid interface. vertical...
Plastic waste is ubiquitously spread across the world and its smaller analogs—microplastics nanoplastics—raise particular health concerns. While biological impacts of microplastics nanoplastics have been actively studied, chemical bases for adverse effects are sought after. This work explores contributory factors by combining results from in vitro model mammalian membrane experimentation to assess outcome cell/nanoplastic interactions molecular detail, inspecting individual contribution...
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsTheme Sections 158:139-149 (1997) - doi:10.3354/meps158139 Utilization of subtropical seagrass meadows by newly settled red drum Sciaenops ocellatus: patterns distribution and growth Jay R. Rooker*, Scott A. Holt The University Texas at Austin, Science Institute, 750 Channelview Drive, Port Aransas, 78373, USA *E-mail:...
To many biophysical characterisation techniques, biological membranes appear as two-dimensional structures with details of their third dimension hidden within a 5 nm profile. Probing this structure requires methods able to discriminate multiple layers few Ångströms thick. Given sufficient resolution, neutron can provide the required discrimination between different biochemical components, especially when selective deuteration is employed. We have used state-of-the-art reflection methods,...
We have investigated a novel method of remotely switching the conformation weak polybase brush using an applied voltage. Surface-grafted polyelectrolyte brushes exhibit rich responsive behavior and show great promise as "smart surfaces", but existing methods involve physically or chemically changing solution in contact with brush. In this study, high grafting density poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) were grown from silicon surfaces atom transfer radical polymerization....
The Chloride Intracellular ion channel protein CLIC1 has the ability to spontaneously insert into lipid membranes from a soluble, globular state. precise mechanism of how this occurs and what regulates insertion is still largely unknown, although factors such as pH redox environment are known contributors. In current study, we demonstrate that presence concentration cholesterol in membrane spontaneous well its activity. study employed pressure versus area change measurements Langmuir...
A model membrane system has been developed, which mimics the outer of Gram negative bacteria. The structure is based on a tethered monolayer fused with vesicles containing lipopolysaccharide molecules. effect composition and lipids in layer structural electrical properties investigated. By using electrochemical impedance spectroscopy as well neutron scattering techniques, it could be shown that relatively high tethering density small amount diluting leaflet leads to formation stable solid...
Lubricin (LUB) is a "mucin-like" glycoprotein found in synovial fluids and coating the cartilage surfaces of articular joints, which now generally accepted as one body's primary boundary lubricants antiadhesive agents. LUB's superior lubrication antiadhesion are believed to derive from its unique interfacial properties by LUB molecules adhere (and biomolecules, such hyaluronic acid collagen) through discrete interactions localized two terminal end domains. These regionally specific lead...
We report the X-ray and neutron reflectometry measurements of structural changes caused by chemical denaturation a surface excess bovine milk protein, β-lactoglobulin. The thickness diffuse protein layer was used as an order parameter there no corresponding increase in function guanidinium chloride (G.HCl) concentration. A thermodynamic analysis performed gave interfacial free energy unfolding absence denaturant (ΔG0). This energy, lower than bulk solution, shows that air−water interface has...
This review presents the implementation and full characterization of polarization equipment time-of-flight neutron reflectometer PLATYPUS at Australian Nuclear Science Technology Organisation (ANSTO). The functionality efficiency individual components are evaluated found to maintain a high beam with maximum 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers efficiencies 99.7% give control over incident scattered spin direction whole wavelength spectrum available in...
This study explains the importance of phosphate moiety and H3O+ in controlling ionic flux through phospholipid membranes. We show that despite an increase concentration when pH is decreased, level conduction bilayers reduced. By modifying lipid structure, we dominant determinant membrane hydrogen bonding between oxygens on adjacent phospholipids. The modulation with proposed to arise from varying concentrations altering molecular area per geometry conductive defects already present membrane....
The fabrication process for dye-sensitized solar cells (DSCs) is well-established; yet, reported reliabilities of DSC device photovoltaic properties have been the subject widespread controversy. will naturally affect these properties, wherein most susceptible component its working electrode, which comprises a dye···TiO2 interface. While various analytical chemistry methods probed this indirectly, molecular structure interface has not tracked with varying dye sensitization conditions, via any...