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Instruments / Technical Area	Publication Details	Published
I07-Surface & interface diffraction	Changes to lung surfactant monolayers upon exposure to gas phase ozone observed using X-ray and neutron reflectivity Joanna M. Hemming , Justyna Szyroka , Gracia Shokano , Thomas Arnold , Maximilian W. A. Skoda , Adrian R. Rennie , Katherine C. Thompson Environmental Science: Atmospheres 175 DOI: 10.1039/D2EA00032F Diamond Proposal Number(s): [8225, 8733] Open Access Show Abstract ▼ Abstract: Exposure to the secondary pollutant ozone in ambient air is associated with adverse health effects when inhaled. In this work we use surface pressure measurements, combined with X-ray and neutron reflection, to observe changes in a layer of lung surfactant at the air water interface when exposed to gas phase ozone. The results demonstrate that the layer reacts with ozone changing its physical characteristics. A slight loss of material, a significant thinning of the layer and increased hydration of the surfactant material is observed. The results support the hypothesis that unsaturated lipids present in lung surfactant are still susceptible to rapid reaction with ozone and the reaction changes the properties of the interfacial layer.	Jun 2022
	Changes to DPPC domain structure in the presence of carbon nanoparticles Alan Sheridan , Jonathan M. Slater , Thomas Arnold , Richard A. Campbell , Katherine C. Thompson Langmuir DOI: 10.1021/acs.langmuir.7b01077 Open Access Show Abstract ▼ Abstract: DPPC (dipalmitoylphosphatidylcholine) is a disaturated lipid capable of forming closely packed monolayers at the air–liquid interface of the lung and allows the surface tension within the alveoli to reduce to almost zero and thus prevent alveolar collapse. Carbon nanoparticles are formed in natural and man-made combustion events, including diesel engines, and are capable of reaching the alveolar epithelium during breathing. In this work, we have used Brewster angle microscopy and neutron reflectivity to study the effect of differing concentrations of carbon nanoparticles on the structure of DPPC monolayer as the monolayer is subject to compression and expansion. The results show that the inclusion of carbon nanoparticles within a DPPC monolayer affects the formation and structure of the lipid domains. The domains lose their circular structure and show a crenated structure as well as a reduction in overall size of the domains. This change in structure is also evident following expansion of the lipid monolayer, suggesting that some carbon nanoparticles may remain associated with the monolayer. This observation could have an important implication regarding the removal of nanosized airborne pollutants from the human lung.	Sep 2017
I22-Small angle scattering & Diffraction	ABC triblock copolymer worms: synthesis, characterization, and evaluation as pickering emulsifiers for millimeter-sized droplets C. J. Mable , K. L. Thompson , M. J. Derry , O. O. Mykhaylyk , B. P. Binks , S. P. Armes Macromolecules 49, 7897 - 7907 DOI: 10.1021/acs.macromol.6b01729 Diamond Proposal Number(s): [10237] Open Access Show Abstract ▼ Abstract: Polymerization-induced self-assembly (PISA) is used to prepare linear poly(glycerol monomethacrylate)–poly(2-hydroxypropyl methacrylate)–poly(benzyl methacrylate) [PGMA–PHPMA–PBzMA] triblock copolymer nano-objects in the form of a concentrated aqueous dispersion via a three-step synthesis based on reversible addition–fragmentation chain transfer (RAFT) polymerization. First, GMA is polymerized via RAFT solution polymerization in ethanol, then HPMA is polymerized via RAFT aqueous solution polymerization, and finally BzMA is polymerized via “seeded” RAFT aqueous emulsion polymerization. For certain block compositions, highly anisotropic worm-like particles are obtained, which are characterized by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The design rules for accessing higher order morphologies (i.e., worms or vesicles) are briefly explored. Surprisingly, vesicular morphologies cannot be accessed by targeting longer PBzMA blocks—instead, only spherical nanoparticles are formed. SAXS is used to rationalize these counterintuitive observations, which are best explained by considering subtle changes in the relative enthalpic incompatibilities between the three blocks during the growth of the PBzMA block. Finally, the PGMA–PHPMA–PBzMA worms are evaluated as Pickering emulsifiers for the stabilization of oil-in-water emulsions. Millimeter-sized oil droplets can be obtained using low-shear homogenization (hand-shaking) in the presence of 20 vol % n-dodecane. In contrast, control experiments performed using PGMA–PHPMA diblock copolymer worms indicate that these more delicate nanostructures do not survive even these mild conditions.	Oct 2016
I22-Small angle scattering & Diffraction	Framboidal ABC triblock copolymer vesicles: a new class of efficient Pickering emulsifier C. J. Mable , N. J. Warren , K. L. Thompson , O. O. Mykhaylyk , S. P. Armes Chemical Science DOI: 10.1039/C5SC02346G Open Access Show Abstract ▼ Abstract: Pickering emulsions offer important advantages over conventional surfactant-stabilized emulsions, including enhanced long-term stability, more reproducible formulations and reduced foaming problems. The recent development of polymerization-induced self-assembly (PISA) offers considerable scope for the design of a wide range of block copolymer nanoparticles with tunable surface wettability that may serve as bespoke Pickering emulsifiers. In the present study, we exploit PISA to design a series of model framboidal ABC triblock copolymer vesicles with exquisite control over surface roughness. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) were utilized to characterize these nanoparticles, which were subsequently used to stabilize n-dodecane emulsion droplets in water. The adsorption efficiency, Aeff, of the nanoparticles at the n-dodecane/water interface was determined as a function of increasing vesicle surface roughness using a turbidimetry assay. A strong correlation between su rface roughness and Aeff was observed, with Aeff increasing from 36% up to 94%. This is a significant improvement in Pickering emulsifier efficiency compared to that reported previously for similar vesicles with smooth surfaces. In summary, nanoparticles with appreciable surface roughness are much more effective Pickering emulsifiers and this parameter can be readily fine-tuned using a highly efficient PISA formulation.	Aug 2015
I07-Surface & interface diffraction	Environmental pollutant ozone causes damage to lung surfactant protein B (SP-B) Joanna M. Hemming , Brian R. Hughes , Adrian R. Rennie , Salvador Tomas , Richard A. Campbell , Arwel V. Hughes , Thomas Arnold , Stanley W. Botchway , Katherine C. Thompson Biochemistry 54 (33), 5185 - 5197 DOI: 10.1021/acs.biochem.5b00308 PMID: 26270023 Diamond Proposal Number(s): [7258] Open Access Show Abstract ▼ Abstract: Lung surfactant protein B (SP-B) is an essential protein found in the surfactant fluid at the air–water interface of the lung. Exposure to the air pollutant ozone could potentially damage SP-B and lead to respiratory distress. We have studied two peptides, one consisting of the N-terminus of SP-B [SP-B(1–25)] and the other a construct of the N- and C-termini of SP-B [SP-B(1–25,63–78)], called SMB. Exposure to dilute levels of ozone (∼2 ppm) of monolayers of each peptide at the air–water interface leads to a rapid reaction, which is evident from an increase in the surface tension. Fluorescence experiments revealed that this increase in surface tension is accompanied by a loss of fluorescence from the tryptophan residue at the interface. Neutron and X-ray reflectivity experiments show that, in contrast to suggestions in the literature, the peptides are not solubilized upon oxidation but rather remain at the interface with little change in their hydration. Analysis of the product material reveals that no cleavage of the peptides occurs, but a more hydrophobic product is slowly formed together with an increased level of oligomerization. We attributed this to partial unfolding of the peptides. Experiments conducted in the presence of phospholipids reveal that the presence of the lipids does not prevent oxidation of the peptides. Our results strongly suggest that exposure to low levels of ozone gas will damage SP-B, leading to a change in its structure. The implication is that the oxidized protein will be impaired in its ability to interact at the air–water interface with negatively charged phosphoglycerol lipids, thus compromising what is thought to be its main biological function.	Aug 2015

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