(Anti)viral Material Design Guided by Scattering Methods

Viruses are nature’s own nanoparticles that are highly symmetric and monodisperse in size and shape with well-defined surface chemistry. They have evolved for optimal cell interactions, genetic information delivery and replication by the host cell over millions of years. These features render them into very efficient pathogens that place a severe burden onto the health of our society. At the same time, they are highly interesting objects for colloidal studies and building blocks for advanced bio-inspired materials for health applications. Their characterisation requires sophisticated experimental techniques such as scattering of X-rays, neutrons, and light to probe structures and interactions from the nanometre to the micrometre length-scale in solution. This contribution summarizes the recent progress in the field of virus self-assembly and virus-based biopolymer composites for advanced material design. It discusses the advances and highlights some of the challenges in the characterization of structure and dynamics in these materials with a focus on scattering techniques. It further demonstrates selected applications in the field of food and water purification

Supramolecular structures in lipid digestion and implications for functional food delivery

The daily diet is important for our survival, health, and wellbeing. Functional food materials, which tailor the digestion process, can help maintaining and even improving human health and lifestyle. Knowledge on how food products, particularly food emulsions such as milk, interact with the digestive system, where they transform into supramolecular structures, can have a direct impact on the rational design of such advanced materials for functional food delivery applications. These materials have the potential to be personalized to digestive conditions and dietary nutrient requirements of the consumer or patient. They could help maintaining the uptake of codelivered nutrients and drugs even under compromised digestion conditions such as a fat maldigestion, a low bile salt concentration, or a limited lipase action. Such conditions are found, for instance, in preterm infants or patients with digestive disorders such as chronic pancreatitis or pancreatic insufficiency. Tailored nanostructure formation and transformation in these materials may further trigger the digestion rate and thus have an impact on the related feeling of satiety, which may help curing eating disorders and reduce the societal challenges of obesity and related diseases. In this contribution, the specific focus is set on discussing the equilibrium and dynamic colloidal properties of food emulsion droplets during digestion and their implications for designing nature- inspired functional food materials. These investigations provide a perspective toward the design of personalized food colloids

Change Detection im städtischen Umfeld von Graz/Österreich mit sehr hoch auflösenden UltraCamDaten

Dieser Beitrag befasst sich mit der Analyse von Landnutzungsänderungen mittels hochauflösender UltraCam-Daten in einer städtischen Umgebung. Das Hauptziel ist es, herauszufinden, ob die Daten geeignet sind, um Landnutzungs- bzw. Landschaftsveränderungen in Städten, die sich durch hohe Heterogenität und rasche Veränderung auszeichnen, halbautomatisch zu erkennen. Die theoretischen Ansätze und Fernerkundungsänderungserfassungsprinzipien werden im ersten Teil des Beitrages behandelt. Die Anzahl der Änderungserkennungsmethoden ist enorm und daher wird ein "Stand der Technik" präsentiert. Der zweite Hauptteil widmet sich der Entwicklung einer Änderungserkennungsmethode für Testgebiete der Stadt Graz und deren Anwendung auf das gesamt Stadtgebiet. Dabei wird ein objektbasiertes, wissensbasiertes Hybridänderungs-Erkennungsverfahren, bzw. die Integration von „image differencing, image rationing and principle component analysis“ angwandt. Die Umwelteinflüsse und Dateneigenschaften, die einen großen Einfluss auf die Genauigkeit des Änderungserfassungsergebnisses haben, werden sowohl für die Befliegungszeiträume (September 2007, Juni 2011 und März/April 2015) dokumentiert und erörtert. Der letzte Teil dieses Aufsatzes beschäftigt sich mit der Diskussion der Ergebnisse der Change Detection Analysen und der Eignung der erreichten Methodik für die Anwendungen in der städtischen Planung durch das Magistrat Graz

pH driven colloidal transformation of MS2 virus particles for water purification

Viral infection due to contaminated drinking water is the main cause of infantile death by diarrheal disease [1]. Viruses are difficult to remove by common gravity driven filters due to their nanometer scale size. With the global goal of improving virus removal in drinking water treatments, the colloidal structure of a virus model, MS2 bacteriophage, has been investigated; the effects of pH and Suwannee River natural organic matter in water have been studied [2]. Dynamic light scattering, small angle X-ray scattering and cryogenic transmission electron microscopy were used to characterize the colloidal structure of MS2 in water. The results show that the bacteriophage MS2 is a spherical particle with a core-shell type structure and a total diameter of 27nm. The RNA core has a radius of about 8nm and the protein shell forming the virus capsid is about 6nm thick. The water pH was discovered to have a major influence on the colloidal structure of the virus: at pH above 5, interparticle repulsions stabilize the virus solution. A decrease in pH to 3 led to diminishing of the repulsion forces and micrometer sized virus aggregates. This aggregation process was reversible upon circulating the water pH. In addition, the presence of Suwannee River natural organic matter that simulates the organic components in surface water was found to sterically stabilize the virus particles, reducing aggregates size and promoting disaggregation with pH increase. These findings will allow a better understanding of virus interactions and can guide the design of advanced water filtration processes for virus removal. Please click Additional Files below to see the full abstract

Internal lamellar and inverse hexagonal liquid crystalline phases during the digestion of krill and astaxanthin oil-in-water emulsions

Krill oil represents an important alternative natural source of omega-3 (ω-3) polyunsaturated fatty acids (PUFAs). Considering the beneficial health effects of these essential fatty acids, particularly in various disorders including cancer, cardiovascular, and inflammation diseases, it is of paramount importance to gain insight into the digestibility of krill oil. In this work, we study the fate of krill oil-in-water emulsion, stabilized by sodium caseinate, during lipolysis by coupling time-resolved synchrotron small-angle X-ray scattering (SAXS) to flow-through lipolysis model. For gaining further insight into the effect of ω-3 PUFA-containing oil type on the dynamic structural features occurring during lipolysis, two additional astaxanthin oil-in-water emulsions, stabilized using either sodium caseinate or citrem, were subjected to lipolysis under identical experimental conditions. In addition to the difference in lipid composition in both oils, ω-3 PUFAs in astaxanthin oil, similar to fish oil, exist in the form of triacylglycerols; whereas most of those in krill oil are bound to phospholipids. SAXS showed the formation of highly ordered nanostructures on exposure of these food emulsions to the lipolysis medium: the detection of a biphasic feature of coexisting inverse hexagonal (H2) and lamellar (Lα) liquid crystalline phases in the digested krill oil droplets' interiors, as compared to a neat Lα phase in the digested astaxanthin oil droplets. We discuss the dynamic phase behavior and describe the suggested important role of these phases in facilitating the delivery of nutrients throughout the body. In addition, the potential implication in the development of food and drug nanocarriers is briefly described

pH-responsive nano-self-assemblies of the anticancer drug 2-hydroxyoleic acid

pH-responsive lipid nanocarriers have the potential to selectively target the acidic extracellular pH environment of cancer tissues and may further improve the efficacy of chemotherapeutics by minimizing their toxic side-effects. Here, we present the design and characterization of pH-sensitive nano-self-assemblies of the poorly water-soluble anticancer drug 2-hydroxyoleic acid (2OHOA) with glycerol monooleate (GMO). pH- triggered nanostructural transformations from 2OHOA/GMO nanoparticles with an internal inverse hexagonal structure (hexosomes) at pH around 2.0–3.0, via nanocarriers with an internal inverse bicontinuous cubic structure (cubosomes) at pH 2.0–4.5, to vesicles at pH 4.5–7.4 were observed with synchrotron small-angle X-ray scattering, and cryogenic transmission electron microscopy. ζ-potential measurements highlight that the pH-driven deprotonation of the carboxylic group of 2OHOA, and the resulting charge-repulsions at the lipid–water interface account for these nanostructural alterations. The study provides detailed insight into the pH-dependent self-assembly of 2OHOA with GMO in excess buffer at physiologically relevant pH values, and discusses the effects of pH alterations on modulating their nanostructure. The results may guide the further development of pH-responsive anticancer nanocarriers for the targeted delivery of chemotherapeutics to the local microenvironment of tumor cells

Donor‐acceptor Stenhouse adduct-polydimethylsiloxane-conjugates for enhanced photoswitching in bulk polymers

Donor–acceptor Stenhouse adducts (DASAs) are a rapidly emerging class of visible light-activated photochromes and DASA-functionalized polymers hold great promise as biocompatible photoresponsive materials. However, the photoswitching performance of DASAs in solid polymer matrices is often low, particularly in materials below their glass transition temperature. To overcome this limitation, DASAs are conjugated to polydimethylsiloxanes which have a glass transition temperature far below room temperature and which can create a mobile molecular environment around the DASAs for achieving more solution-like photoswitching kinetics in bulk polymers. The dispersion of DASAs conjugated to such flexible oligomers into solid polymer matrices allows for more effective and tunable DASA photoswitching in stiff polymers, such as poly(methyl methacrylate), without requiring modifications of the matrix. The photoswitching of conjugates with varying polymer molecular weight, linker type, and architecture is characterized via time-dependent UV–vis spectroscopy in organic solvents and blended into polymethacrylate films. In addition, DASA-functionalized polydimethylsiloxane networks, accessible via the same synthetic route, provide an alternative solution for achieving fast and efficient DASA photoswitching in the bulk owing to their intrinsic softness and flexibility. These findings may contribute to the development of DASA-functionalized materials with better tunable, more effective, and more reversible modulation of their optical properties

Lipid-hydrogel films for sustained drug release

We report a hybrid system, fabricated from nanostructured lipid particles and polysaccharide based hydrogel, for sustained release applications. Lipid particles were prepared by kinetically stabilizing self-assembled lipid nanostructures whereas the hydrogel was obtained by dissolving kappa-carrageenan (KC) in water. The drug was incorporated in native as well as lipid particles loaded hydrogels, which upon dehydration formed thin films. The kinetics of drug release from these films was monitored by UV–vis spectroscopy while the films were characterized by Fourier transform infra-red (FTIR) spectroscopy and small angle X-ray scattering techniques. Pre-encapsulation of a drug into lipid particles is demonstrably advantageous in certain ways; for instance, direct interactions between KC and drug molecules are prohibited due to the mediation of hydrophobic forces generated by lipid tails. Rapid diffusion of small drug molecules from porous hydrogel network is interrupted by their encapsulation into rather large sized lipid particles. The drug release from the lipid-hydrogel matrix was sustained by an order of magnitude timescale with respect to the release from native hydrogel films. These studies form a strong platform for the development of combined carrier systems for controlled therapeutic applications