Leukemic cells and human hematopoietic progenitor cells expressing CD44 receptors have the ability to attach and roll on hyaluronan. We investigated quantitatively the adhesion behavior of leukemic cell lines and hematopoietic progenitor cells on thin films of the polysaccharides hyaluronan and alginate in a microfluidic system. An applied flow enhances the interaction between CD44-positive cells and hyaluronan if a threshold shear stress of 0.2 dyn/cm(2) is exceeded. At shear stress ∼1 dyn/cm(2), the cell rolling speed reaches a maximum of 15 μm/s. Leukemic Jurkat and Kasumi-1 cells lacking CD44-expression showed no adhesion or rolling on the polysaccharides whereas the CD44-expressing leukemic cells KG-1a, HL-60, K-562, and hematopoietic progenitor cells attached and rolled on hyaluronan. Interestingly, the observations of flow-induced cell rolling are related to those found in the recruitment of leukocytes to inflammatory sites and the mechanisms of stem-cell homing into the bone marrow.

Nanoscale TiO2 photocatalysts are key materials for convenient wastewater treatment and other essential cleaning processes. Immobilization of TiO2 nanoparticles (NPs) is thus indispensable for the facile handling and separation of nanocatalysts as well as for minimizing their potential health and environmental hazards. Silicone nanofilaments are introduced as a new flexible carrier type for titania NPs because they are compatible with a wide range of substrates and they display high chemical stability. TiO2‐NPs are deposited on glass slides covered with thin carpets of silicone nanofilaments in a single reaction step starting from TiF4 and optimized ethanol/water ratios. The resulting composites are characterized using a wide range of electron microscopy and other analytical techniques, and their photocatalytic activity in the decomposition of methylene blue (MB) is superior to immobilized TiO2 references on plain substrates.

Naturally occurring biomolecules are sustainable and green precursors for the development of new materials. Within this family of natural materials, cellulose nanocrystals (CNCs) have emerged as one of the most promising materials because of their outstanding physico-chemical properties and the possibility to produce them in large quantities. One key trait of CNCs is their ability to self-assemble into a chiral nematic liquid crystalline phase. In this review, we discuss how templating can be used to transfer the three-dimensional structure of liquid crystalline phases onto solid materials. This is followed by examples that illustrate the fascinating properties and potential applications that arise from the resulting nanostructured materials such as sensing and catalysis. We then summarize efforts to use the liquid crystalline phase of a selection of other biopolymers for templating. While nanocrystalline chitin, having very similar properties to CNCs, has been successfully employed to make a variety of new materials, efforts to template liquid crystal phases of other biomolecules have been met with limited success. However, we discuss virus nanoparticles and collagen as examples to highlight further possibilities for materials research.

One-dimensional (1D) nanostructures have been identified as key technology for future devices and integrated into surface-bound materials. The roughness of surface-bound 1D silicone nanofilaments (SNFs) has been used extensively to create surfaces with extreme wetting properties and as carrier material. Electron microscopy has shown that this material is made of individual filaments with diameters spanning tens of nanometers and a length of several micrometers which arrange into a highly entangled quasi-porous network. However, a comprehensive analysis of the three-dimensional (3D) superstructure has remained elusive so far. In this study, focused ion beam nanotomography (FIB-nt) is used to quantify the otherwise hardly accessible structural parameters roughness (12.68) and volume fraction (2.80). The volume fraction is anisotropic, and two major species of SNFs are quantified to contribute equally to the overall surface area. Spatial statistics reveals a self-avoiding growth pattern of SNFs over the substrate, and a 3D model of the data is rendered. The presented analysis therefore significantly advances the understanding of SNF surface coatings with regard to their structure at the nano-and microscale. Finally, the described procedure may serve as a useful tool to analyze other surface-bound 1D nanostructures of similar complex arrangement. ■ INTRODUCTIONThe properties of materials depend on both their chemistry and their morphology. The latteri.e., the influence of structure becomes especially apparent when the material dimensions approach the nanoscale. Here, the high surface to volume ratio together with quantum size effects leads to reactive, magnetic, optical, and electronic behavior that often differs substantially from that of the respective bulk materials. 1,2 Within the class of nanomaterials, one-dimensional (1D) structures such as gold and oxidic nanorods, 3−11 carbon nanotubes, 12−15 and nanowires in general 16−20 have been identified as key components for the fabrication of novel nanodevices. 21,22 Their assembly into three-dimensional (3D) superstructures of higher order such as nanoarrays, nanoforests, and networks has led to the development of biosensors, 23−27 surfaces with superhydrophobic and self-cleaning properties, 28,29 and electrode materials for supercapacitors 30−34 and dye-sensitized solar cells. 35−40 Morphology and surface area of the 3D superstructure are critical parameters in all these applications because they determine the interface with reactants and analytes but are often difficult to quantify.A decade ago surface-bound polysiloxane structures have been added to the family of 1D nanomaterials, and their properties and applications have been reviewed in detail. 41−43 Most applications for these so-called silicone nanofilaments (SNFs) have focused on the extreme wetting behavior that can be inferred by this coating. 41,44−47 Salient benefits of SNFs are their production via convenient vapor-phase or solvent-based routes at room temperature accompanied by their excellent env...

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