Hydrophilic bio-based polymers by radical copolymerization of cyclic vinyl ethers derived from glycerol

Structure Determination of 1,3-Dioxolane-Containing Lipids from the Marine Sponge Leucetta sp. Using Chiral 1H NMR Analysis of Model Systems

Chemical investigation of n-hexane extract from the marine sponge Leucetta sp. led to the isolation of five new lipids, 1-5, each characterized by a substituted dioxolane core. The structures of 1-5 were established based on the interpretation of NMR and HRESIMS data. To assign the absolute configuration at C-1', model systems consisting of diastereomers at C-2, C-4, and C-1' of the dioxolane core were prepared from a chiral glycerol dimethylacetal. 1H NMR inspection of model compounds revealed that a pair of C-1' epimers, 11a/c and 11b/d, was indistinguishable, restricting structural assignment by direct comparison of NMR data. In addition, the lack of chromophores in the dioxolane core resulted in unreliable ECD results, with Cotton effects appearing below 190 nm. As an alternative, a chiral NMR method using Eu(hfc)3 revealed notable lanthanide-induced shifts, allowing the spectroscopic discrimination of 11a/c and ent-11a/c. Therefore, the absolute configuration of all five new lipids was determined to be 2S, 4S, 1'S by direct comparison with the Eu(hfc)3-induced 1H NMR data.

Optimized sample buffer for dispersed, high-resolution capillary zone electrophoretic separation of Escherichia coli B

Capillary zone electrophoresis (CZE) is a powerful tool for high resolution chemical separations. Applying CZE to microbial samples may facilitate a deeper understanding of bacterial physiology and behavior. However, the study of complex microbial samples has been limited by the uncontrolled hetero-aggregation of bacterial cells under an applied electric field. We tested a wide range of sample buffers and buffer additives for the optimization of bacterial CZE separations using a 20 mM Tris-HCl background electrolyte. By modifying the sample buffer, but not the background electrolyte, we retain constant separation conditions, which aids in the comparison of the sample buffer additives. We report optimized methods for automated CZE separation and simultaneous fractionation of Escherichia coli B, which is one of the two most widely used wild-type strains. A modified sample buffer containing neutral salts and the addition of glycerol produced a 20-fold increase in loading capacity and a reduction in peak width/broadening of 86% in comparison to previously reported work. In addition, the glycerol-modified sample buffer appears to reduce the persistent aggregation and adhesion to the capillary walls during electrophoretic separations of complex environmental microbiota.