BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:The Internal structure of a NIPAM brush layer DTSTART;VALUE=DATE-TIME:20181120T224500Z DTEND;VALUE=DATE-TIME:20181120T230500Z DTSTAMP;VALUE=DATE-TIME:20260809T073500Z UID:indico-contribution-636-2332@events01.synchrotron.org.au DESCRIPTION:Speakers: Ben Humphreys (University of Newcastle)\nThe interna l structure of a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) bru sh coating has been investigated via neutron reflectometry and small angle neutron scattering (SANS).[1] PNIPAM is a thermoresponsive polymer with a n entropically driven lower critical solution temperature (LCST). Below th e LCST\, the polymer will hydrogen bond with H2O\, solubilising the chains . Above the LCST\, the entropic penalty from solubilising the hydrophobic regions of the polymer becomes too great\, and PNIPAM becomes insoluble. W hen tethered to a surface in the polymer brush regime\, the brush layer is swollen at low temperatures and collapsed above the LCST. Furthermore\, t his abrupt LCST broadens into a temperature transition range spanning 10-2 0 °C.[2] \nWe have examined the influence of molecular weight\, ionic str ength and salt identity on the temperature induced swelling/collapse trans ition of PNIPAM brushes using ellipsometry\, QCM-D\, AFM\, contact angle m easurements and DLS.[1-2] These techniques provided a detailed understandi ng of bulk and surface properties of the PNIPAM systems investigated. The use of neutrons to interrogate these systems\, however\, has enabled subtl e variation in the brush volume fraction profile normal to the substrate t o be elucidated (Fig. 1). This highlights any variations related to surfac e curvature\, brush thickness\, surface confinement\, ionic strength and s alt identity.\n\n[1] T. J. Murdoch\, B. A. Humphreys\, et. al.\, Macromole cules 2016\, 49\, 6050-6060.\n[2] (a) B. A. Humphreys\, et al.\, JCIS 2018 \, 516\, 153-161\; (b) B. A. Humphreys\, et. al.\, PCCP 2016\, 18\, 6037-6 046\; (c) T. J. Murdoch\, B. A. Humphreys\, et. al.\, JCIS 2018\, 526\, 42 9-450.\n\nhttps://events01.synchrotron.org.au/event/84/contributions/2332/ LOCATION:AINSE Conference Centre New Illawarra Road Lucas Heights NSW 2234 Australia URL:https://events01.synchrotron.org.au/event/84/contributions/2332/ END:VEVENT BEGIN:VEVENT SUMMARY:Hierarchcial structure of solid lipid nanoparticles DTSTART;VALUE=DATE-TIME:20181120T234500Z DTEND;VALUE=DATE-TIME:20181121T000500Z DTSTAMP;VALUE=DATE-TIME:20260809T073500Z UID:indico-contribution-636-2336@events01.synchrotron.org.au DESCRIPTION:Speakers: Rohan Shah (Department of Chemistry and Biotechnolog y)\nSuspensions of solid lipid nanoparticles (SLNs) stabilized with emulsi fiers have been extensively investigated as drug carriers since the 1990s\ , although details of their ultrastructure are poorly defined. Previously\ , our group reported a novel microwave-assisted microemulsion-based techni que to prepare SLNs. Ultrastructure generally relates to interior of the p article and can relate to internal partitioning through\, for example\, a core-shell structure. It can also relate to the formulation itself\, inclu ding the particle itself\, but can also include structures such as micelle s\, which may be simultaneously present.\n\nOur previous investigations re vealed that SLNs were prepared by the novel microemulsion technique have s ize of 200-300 nm. Preliminary multi-angle SLS/DLS studies indicated core- shell type of SLNs. To understand the detailed ultrastructure of these SLN s\, ultra-small angle neutron scattering (USANS) and small angle neutron s cattering (SANS) experiments were conducted on suspensions of hydrogenated stearic acid SLNs stabilized with hydrogenated Tween 20 surfactant in D2O . Together\, SANS and USANS gave a combined Q range of 4.7 × 10^-5 to 6 × 10^-1 Å^−1 (corresponding to a size range of ~ 1 nm - 15 µm). This extended Q range allows a comprehensive understanding of the hierarchical structure of SLNs. The SANS/USANS data are consistent with the multi-lengt h scale structure of SLNs having polydispersed large particles at the micr oscale level\, intermediate between spheres to rod\, with roughened surfac es. At the nanoscale level\, the results are consistent with the SLNs solu tion having an ellipsoidal shape intermediate between spheres and rods\, w ith a crossover from mass fractals to surface fractals. The elucidation of this structure is particularly important given that the structure influen ces the stability and drug release properties of the nanoparticles. These results will assist in the development of systems with desired shape and p roperties.\n\nhttps://events01.synchrotron.org.au/event/84/contributions/2 336/ LOCATION:AINSE Conference Centre New Illawarra Road Lucas Heights NSW 2234 Australia URL:https://events01.synchrotron.org.au/event/84/contributions/2336/ END:VEVENT BEGIN:VEVENT SUMMARY:Examining the structural and mechanical implications of surfactant s on neutral polymer brushes through neutron reflectometry DTSTART;VALUE=DATE-TIME:20181120T232500Z DTEND;VALUE=DATE-TIME:20181120T234500Z DTSTAMP;VALUE=DATE-TIME:20260809T073500Z UID:indico-contribution-636-2334@events01.synchrotron.org.au DESCRIPTION:Speakers: Isaac Gresham (The University of New South Wales)\nL ayers of densely-tethered polymers (polymer brushes) are of interest due t o their potential applications as nano-actuators\, biocompatible coatings\ , and switchable lubricating or antifouling surfaces. These applicable pro perties are dependant on the structure of the polymer interface\, so it is important that the structural effects of common compounds and relevant en vironmental variables be understood. Neutron Reflectometry (NR) is the onl y technique capable of providing detailed structural resolution of solvate d multi-component polymer brush systems due to its penetrating power and t he possibility of isotopic substitution.\n\nHere we present a Neutron Refl ectometry study on the effects of surface-active molecules (surfactants) o n two neutral polymer brushes\, poly(ethylene oxide) (PEO) and Poly(N-isop ropylacrylamide) (PNIPAM)\, focusing on small\, single tail surfactants. P EO is a widely used biocompatible polymer with a range of medical and comm ercial applications\, whilst PNIPAM is a well known thermoresponsive polym er\, undergoing a swollen to collapsed transition over its critical soluti on temperature (CST) of 32˚C. We show that these two polymers exhibit sim ilar yet distinct interactions with surfactants\, with the observed differ ences having implications for the mechanism of brush-surfactant interactio n. The presence of surfactants was found to raise the CST of PNIPAM\; we s how that this effect is dependent strongly on surfactant identity and conc entration. As part of this work we have developed new modelling techniques for the analysis of NR data from polymer brush interfaces. These advancem ents will be explained in the context of the data at hand\, and their appl icability to other soft diffuse interfaces will be briefly discussed.\n\nh ttps://events01.synchrotron.org.au/event/84/contributions/2334/ LOCATION:AINSE Conference Centre New Illawarra Road Lucas Heights NSW 2234 Australia URL:https://events01.synchrotron.org.au/event/84/contributions/2334/ END:VEVENT BEGIN:VEVENT SUMMARY:Nanoplastics – protein interaction: A scattering study of transi tion from soft and hard corona DTSTART;VALUE=DATE-TIME:20181120T230500Z DTEND;VALUE=DATE-TIME:20181120T232500Z DTSTAMP;VALUE=DATE-TIME:20260809T073500Z UID:indico-contribution-636-2333@events01.synchrotron.org.au DESCRIPTION:Speakers: Shinji Kihara (School of Chemical Sciences\, The Un iversity of Auckland\, Auckland 1010\, New Zealand )\nThere is growing con cern about plastic waste in the environment\, and its impact on biological organisms. While bulk plastics are thought to be non-toxic\, when the pla stics break down to a sub-micron length scale (i.e. nanoplastics)\, they o btain extra mobility inside living things\, and may cause various adverse effects [1\,2]. This\, coupled with a lack of knowledge surrounding the da ngers from different types of plastics\, prevents well-designed responses to the problem. Hypothetically\, the potential adverse effects are caused by protein denaturation\, oxidative stress and/or cellular membrane damage . However\, the inherent complexity of biological systems makes it challen ging to gain a mechanistic understanding. Adding complexity to this proble m\, the potential adverse effects are highly dependent on the nature of na noparticles (NPs) – the contributing factors could include elemental com position\, chemistry of the plastic surface\, and/or size of the plastic p article [3\,2\,4].\n\nWhen in biological systems\, nanoplastics are surrou nded by various types of proteins5. The structure of proteins surrounding nanoplastics are important parameters to understand the interaction of nan oplastic/protein composite. We carried out light scattering and small angl e neutron scattering (SANS) experiments to explore the structure of the pr otein corona on monodisperse polystyrene spheres using a model protein hum an serum albumin (HSA). The geometry of the PS/HSA complex was investigate d with a contrast matching method. The transition from a “soft” to a “hard” interaction between the nanoparticle and the protein was observ ed when pH is lowered from 7.4\, and the implications of this on nanoplast ic toxicity is discussed.\n\nReferences\n\nSharma\, S.\; Chatterjee\, S. E nvironmental Science and Pollution Research 2017\, 24\, 21530-21547.\nLee\ , K.-W.\; Shim\, W. J.\; Kwon\, O. Y.\; Kang\, J.-H. Environmental science & technology 2013\, 47\, 11278-11283.\nMattsson\, K.\; Johnson\, E. V.\; Malmendal\, A.\; Linse\, S.\; Hansson\, L.-A.\; Cedervall\, T. Scientific Reports 2017\, 7\, 11452.\nCui\, R.\; Kim\, S. W.\; An\, Y.-J. Scientific reports 2017\, 7\, 12095.\nTenzer\, S.\; Docter\, D.\; Kuharev\, J.\; Musy anovych\, A.\; Fetz\, V.\; Hecht\, R.\; Schlenk\, F.\; Fischer\, D.\; Kiou ptsi\, K.\; Reinhardt\, C. Nature nanotechnology 2013\, 8\, 772.\n\nhttps: //events01.synchrotron.org.au/event/84/contributions/2333/ LOCATION:AINSE Conference Centre New Illawarra Road Lucas Heights NSW 2234 Australia URL:https://events01.synchrotron.org.au/event/84/contributions/2333/ END:VEVENT END:VCALENDAR