https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:36404 iC₈)₂PO₂) diluted in octane lubricated as effectively as pure IL. However, until now the structure and composition of the lubricating adsorbed layer, which is critical for lubrication, was unknown. Here, the unconfined structure of the IL adsorbed layer at the oil-silica interface has been studied using neutron reflectometry. Multiple neutron contrasts revealed an 8 Å thick adsorbed layer, even at 60 and 80 °C. The ratio of cations and anions in the layer was investigated by synthesizing the IL with deuterated cations and measuring its reflectivity at the oil-silica interface. At 60 °C the layer was composed of 48 ± 6 mol % P₆,₆,₆,₁₄⁺ cations, 24 ± 2 mol % (ⁱC⁸)₂PO₂⁻ anions, and 28 ± 8 mol % octane, while at 80 °C the composition was 50 ± 2 mol % P₆,₆,₆,₁₄⁺, 28 ± 2 mol % (ⁱC₈)₂PO₂⁻ anions, and 22 ± 2 mol % octane. These results reinforce the importance of the judicious selection of IL cations and anions for charged surfaces and support their use in high-temperature applications.]]> Mon 27 Apr 2020 13:54:03 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:51979 Mon 13 Nov 2023 08:48:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:31380 Pseudomonas aeruginosa using neutron reflectometry, together with fluorimetric and calorimetry methods. For the first time, our neutron reflectometry results reveal that the interaction of octapeptin A3 with the Gram-negative outer membrane involves an initial transient polar interaction with the phospholipid and lipid A headgroups, followed by the penetration of the entire octapeptin molecule into the fatty acyl core of the outer membrane. This mechanism contrasts with that of polymyxin B, which specifically targets lipid A, whereas octapeptins appear to target both lipid A and phospholipids. Furthermore, the mechanism of octapeptins does not appear to be highly dependent on an initial complementary electrostatic interaction with lipid A, which accounts for their ability to bind to lipid A of polymyxin-resistant Gram-negative bacteria that is modified with cationic moieties that act to electrostatically repel the cationic polymyxin molecule. The presented findings shed new light on the mechanism whereby octapeptins penetrate the outer membrane of polymyxin-resistant Gram-negative pathogens and highlight their potential as candidates for development as new antibiotics against problematic multi-drug-resistant pathogens.]]> Fri 18 Sep 2020 14:00:17 AEST ]]>