Linear stability of particle-laden thin films

Recent experiments [Zhou, Dupuy, Bertozzi, and Hosoi, Phys. Rev. Lett., 94 (2005)] of particle-laden film flow on an incline demonstrate new behavior distinct from the well-known clear fluid case, including the formation of a particle-rich ridge which can stabilize the advancing contact line with respect to “fingering" perturbations. We consider a model similar to that of Zhou et al. with the additional regularizing effect of shear-induced diffusion. A linear stability analysis demonstrates that particle settling moderately reduces the growth rate of unstable modes, while increasing the most unstable wavelength.     

Determination of trans-resveratrol in Solanum americanum Mill. by HPLC

Solanum americanum Mill. is a plant that belongs to the Solanaceae family, its respective ripe fruit is dark purple. Ripe S. americanum Mill. fruits were submitted to physicochemical characterisation, and their trans-resveratrol contents were quantified by high-performance liquid chromatography. Such determination was executed with fruits at different stages of ripeness and freeze-stored fruits as well. In natura ripe fruit pulp and peel presented average trans-resveratrol amounts of 1.07 and 0.7960 μg per gram of sample, respectively. These amounts are significantly higher when compared to freeze-stored fruit (0.1353 μg of trans-resveratrol per gram of sample) and to other berries. All ripe fruits showed significant amounts of total anthocyanins and total antioxidants. Thus, for the first time, trans-resveratrol has been identified and quantified in S. americanum Mill. fruit samples.     

N‐Carboxyanhydride Polymerization of Glycopolypeptides That Activate Antigen‐Presenting Cells through Dectin‐1 and Dectin‐2

The C‐type lectins dectin‐1 and dectin‐2 contribute to innate immunity against microbial pathogens by recognizing their foreign glycan structures. These receptors are promising targets for vaccine development and cancer immunotherapy. However, currently available agonists are heterogeneous glycoconjugates and polysaccharides from natural sources. Herein, we designed and synthesized the first chemically defined ligands for dectin‐1 and dectin‐2. They comprised glycopolypeptides bearing mono‐, di‐, and trisaccharides and were built through polymerization of glycosylated N‐carboxyanhydrides. Through this approach, we achieved glycopolypeptides with high molecular weights and low dispersities. We identified structures that elicit a pro‐inflammatory response through dectin‐1 or dectin‐2 in antigen‐presenting cells. With their native proteinaceous backbones and natural glycosidic linkages, these agonists are attractive for translational applications.     

Copper-free click chemistry for the in situ crosslinking of photodegradable star polymers

Bifunctional, fluorinated cyclooctynes were used for the in situ "click" crosslinking of azide-terminated photodegradable star polymers, yielding photodegradable polymeric model networks with well-defined structures and tunable gelation times.     

Probing glycosyltransferase activities with the Staudinger ligation

The development of rapid screening methods for probing glycosyltransferase activities is essential for advancing the field of glycobiology. While assays for specific glycosyltransferases exist, there is no generalizable method that can be applied across the enzyme superfamily. Herein we describe a novel glycosyltransferase assay that exploits their unnatural substrate tolerance and the unique chemical reactivity of the azide. We applied this "azido-ELISA" to the family of polypeptide alpha-N-acetylgalactosaminyltransferases (ppGalNAcTs), all of which were able to transfer N-azidoacetylgalactosamine (GalNAz) from the unnatural nucleotide sugar donor UDP-GalNAz. The azide was detected and quantified by Staudinger ligation with a phosphine probe in a microtiter plate format. This approach should be applicable to any glycosyltransferase or group-transfer enzyme that tolerates unnatural azido substrates.