The Effect of Lipopolysaccharide Core Oligosaccharide Size on the Electrostatic Binding of Antimicrobial Proteins to Models of the Gram Negative Bacterial Outer Membrane

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, the role of the uncharged sugar groups in the outer core region of lipopolysaccharide (LPS) in protecting the phosphate-rich inner core region from electrostatic interactions with antimicrobial proteins. Models of the asymmetric Gram negative outer membrane on silicon were prepared with phopshatidylcholine (PC) in the inner leaflet (closest to the silicon), whereas rough LPS was used to form the outer leaflet (facing the bulk solution). We show how salt concentration can be used to reversibly alter the binding affinity of a protein antibiotic colicin N (ColN) to the anionic LPS confirming that the interaction is electrostatic in nature. By examining the interaction of ColN with two rough LPS types with different-sized core oligosaccharide regions we demonstrate the role of uncharged sugars in blocking short-range electrostatic interactions between the cationic antibiotics and the vulnerable anionic phosphate groups

Supply chain performance measurement: the case of the traditional food sector in the EU

The objective of this study is to develop a sound measurement instrument of traditional food supply chain performance integrating the perspectives of different stakeholders. Therefore first, stakeholders’ goals are generalized via focus groups and individual interviews. Second, stakeholders’ goals are consolidated, based on their specificity and conflicting/divergent nature and as a result, supply chain goals are developed. Third, potential performance indicators are listed, supporting the developed supply chain goals. Fourth, key performance indicators (KPIs) are selected. As a result, five main supply chain goals are formulated (traditionalism, efficiency, responsiveness, quality and chain balance) together with their supporting performance indicators. Future research should focus on validating the instrument in other food and non-food sectors

Complementary X-ray, ellipsometry and neutron data from Non-lamellar lipid assembly at interfaces: controlling layer structure by responsive nanogel particles

Figure S1. Effect of temperature on the lattice parameter, a, of a cubic phase composed of GMO-50/DGMO (40/60 weight ratio) alone (open markers) or containing 10 wt% nanogel (black solid markers). Figure S2. SAXS data for the formulations of nanogels dispersed in lipids (85 wt % lipids composed of GMO-50/DGMO at a 40/60 weight ratio) with 15 wt % ethanol at 25 °C and 40 °C. Figure S3. Spectroscopic ellipsometry parameters, Δ (pink circles) and ψ (black triangles), as a function of wavelength for a film of GMO-50:DGMO (40:60 wt%) on silica. Figure S4. (A) Schematic representation of magnetic contrast surfaces used in this study. Figure S5. Neutron reflectivity data for a spin coated film of GMO-50:DGMO (60:40 wt% ratio) containing nanogel (10wt%) at (A) 25°C and (B) 40°C. Figure S6. Diffraction pattern extracted from the off-specular neutron reflectivity patterns in Figure 6 of lipid-only and lipid-nanogel layers at 25 °C and 40 °C