Structural Changes of Cassava Starch Granules after Heating at Intermediate Water Contents

DSC thermograms of cassava starch granules heated at two intermediate moisture contents of 35 and 45% of the total weight (w.t.) reveal the existence of two endothermic steps in their progressive disorganization. Structural changes have been studied by combining polarized light microscopy and electron microscopy (scanning and transmission electron microscopy). An instability of starch granule behaviour, both at granular and crystalline levels is observed at each treatment temperature. As temperature and moisture content increase, the loss of birefringence was observed in an increasing number of granules, suggesting that there is a competition of granules for water. The loss of birefringence initiates first at the hilum and is associated with the formation of cavities in the central region of the granules, showing that the disorganization first affects the less organized areas of the granule. In limited water content conditions, the radial extension of the central cavity towards the granule surface is not observed. The limited crystalline disorganization which is restricted to the inner part of the granule does not allow either a major swelling of granules or an extensive leaching of macromolecules out of granules. Increasing temperatures progressively induced the loss of granular integrity and the development of an homogeneous matrix. These structural changes are in agreement with the cooperative disorganization model of starch crystallites following which the crystalline disorganization is facilitated by the presence of water or by the plasticization of the amorphous regions connected to these crystallites.     

Esterase-Activated,pH-Responsive,and Genetically Targetable Nano-Prodrug for Cancer Cell Photo-Ablation

Activatable prodrugs have drawn considerable attention for cancer cell ablation owing to their high specificity in drug delivery systems. However, phototheranostic prodrugs with dual organelle-targeting and synergistic effects are still rare due to low intelligence of their structures. Besides, the cell membrane, exocytosis, and diffusional hindrance by the extracellular matrix reduce drug uptake. Moreover, the up-regulation of heat shock protein and short singlet-oxygen lifetime in cancer cells hamper photo-ablation efficacy, especially in the mono-therapeutic model. To overcome those obstacles, we prepare an esterase-activated DM nano-prodrug, which is conjugated by diiodine-substituted fluorogenic malachite green derivative (MG-2I) and phototherapeutic agent DPP-OH via hydrolyzable ester linkage, having pH-responsiveness and genetically targetable activity for dual organelles-targeting to optimize photo-ablation efficacy. The DM nanoparticles (NPs) present improved pH-responsive photothermal/photodynamic property by the protonation of diethylaminophenyl units in acidic environment. More importantly, the MG-2I and DPP-OH moieties can be released from DM nano-prodrug through overexpressed esterase; then specifically target lysosomes and mitochondria in CT-26 Mito-FAP cells. Hence, near-infrared DM NPs can trigger parallel damage in dual-organelles with strong fluorescence and effective phototoxicity, thus inducing serious mitochondrial dysfunction and apoptotic death, showing excellent photo-ablation effect based on esterase-activated, pH-responsive, and genetically targetable activities.     

Monitoring Gut Epithelium Serotonin and Melatonin Overflow Provides Spatial Mapping of Inflammation

Electrochemical arrays were used to measure the overflow of serotonin (5-HT) and melatonin (MEL) from the entire colon of healthy mice and mice with chemical-induced inflammatory bowel disease (IBD), to understand the interplay between inflammation and colonic function. We show that 5-HT overflow is increased, whilst MEL levels are reduced, in inflamed tissues. The levels of MEL are increased at the interface between healthy and inflamed regions within the colon and may limit the spread of inflammation. Understanding the interplay between inflammation and mucosal epithelial signalling can provide key insight into colonic function and aid the development of effective therapeutic strategies to treat gastrointestinal diseases.     

On the validity of the thermal explosion model in shock wave initiated nitromethane

By means of Perot Fabry Velocimetry (PFV) we recorded material velocities generated by an intense shock wave (P > 70 kbar) in pure nitromethane. Our experiments show that nitromethane does not behave according to the Campbell-Travis model for detonation in liquid explosives. We do not find any evidence for a so-called superdetonation, which would start behind and overtake the pressure shock wave. Our recordings of material velocities show a behavior of the liquid explosive very similar to that of solid polycrystalline explosives and are compatible with the heterogeneous decomposition scheme.     

Micromotor-Assisted Keratinocytes Migration in a Floating Paper Chip

In vitro epidermis models are important to evaluate and study disease progression and possible dermal drug delivery. An in vitro epidermis model using floating paper chips as a scaffold for proliferation and differentiation of primary human keratinocytes is reported. The formation of the four main layers of the epidermis (i.e., basal, spinosum, granulose, and cornified layers) is confirmed. The development of a cornified layer and the tight junction formation are evaluated as well as the alterations of organelles during the differentiation process. Further, this in vitro model is used to assess keratinocyte migration. Finally, magnetic micromotors are assembled, and their ability to aid cell migration on paper chips is confirmed when a static magnetic field is present. Taken together, this attempt to combine bottom-up synthetic biology with dermatology offers interesting opportunities for studying skin disease pathologies and evaluate possible treatments.     

Partially Bio-Based Polyester Bead Foams via Extrusion Foaming of Poly(butylene terephthalate)/Poly(butylene furanoate) Blends

The interest in bio-based alternatives to classical polyesters such as poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) is steadily growing to achieve a more sustainable approach to polymer materials. In this study, PBT/poly(butylene furanoate) (PBF) blends are prepared, characterized and extrusion foamed. PBF as a bio-based polyester offers two advantages. The ecological footprint of the material is reduced, and additionally, it can be used in Diels-Alder reactions at the blend surface to support fusion of the foamed beads. The blending behavior of the polyesters is investigated using samples prepared in a microcompounder, particularly focused on the miscibility of the blends and transesterification reactions. The blends are thermodynamically immiscible but show a certain degree of transesterification according to nuclear magnetic resonance (NMR) spectroscopy. The morphology of blend beads produced by an extrusion foaming process is analyzed regarding their cell density, cell size distribution, and open-cell content. It is shown that PBF has a positive effect on the bead foam morphology. The use of a bifunctional linker designed for chemical fusion of the bead surfaces allows to obtaining of molded parts, in contrast to beads containing pure PBT.