Reversible Lysine Modification on Proteins by Using Functionalized Boronic Acids

Iminoboronates have been utilized to successfully install azide and alkyne bioorthogonal functions on proteins, which may then be further reacted with their bioorthogonal counterparts. These constructs were also used to add polyethylene glycol (PEG) to insulin, a modification which has been shown to be reversible in the presence of fructose. Finally, iminoboronates were used to assemble a folic acid/paclitaxel small‐molecule/drug conjugate in situ with an IC₅₀ value of 20.7 nM against NCI‐H460 cancer cells and negligible cytotoxicity against the CRL‐1502 noncancer cells.     

Chromium complexes based on thiophene–imine ligands for ethylene oligomerization

A new set of Cr(III) complexes, {L}CrCl₃(THF), based on thiophene–imine ( 2a , L = PhOC₆H₄(N═CH)‐2‐SC₄H₃; 2b , L = PhOC₂H₄(N═CH)‐2‐SC₄H₃; 2c , L = Ph(NH)C₂H₄(N═CH)‐2‐SC₄H₃; 2d , L = PhOC₆H₄(N═CH)‐2‐SC₄H₂‐5‐Ph; 2e , L = Ph(NH)C₂H₄(N═CH)‐2‐SC₄H₂‐5‐Ph) have been prepared and characterized using elemental analysis and infrared spectroscopy. Upon activation with methylaluminoxane, all the chromium complexes generated active systems affording a nonselective distribution of α‐olefins with turnover frequencies in the range 9500–93 500 (mol ethylene) (mol Cr)^?1 h^?1, and producing mostly oligomers (95.0–99.3 wt% of total products). Small amounts of polymer were produced in these oligomerization reactions (0.8–8.2 wt%). The catalytic activities were quite sensitive to the ligand environment. Moreover, the effects of oligomerization parameters (temperature, [Al]/[Cr] molar ratio, time) on the activity and on the product distribution were examined.     

Applicability of Microaerobic Technology to Enhance BTEX Removal from Contaminated Waters

As the addition of low concentrations of oxygen can favor the initial degradation of benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds, this work verified the applicability of the microaerobic technology to enhance BTEX removal in an anaerobic bioreactor supplemented with high and low co-substrate (ethanol) concentrations. Additionally, structural alterations on the bioreactor microbiota were assessed throughout the experiment. The bioreactor was fed with a synthetic BTEX-contaminated water (~ 3 mg L^?1 of each compound) and operated at a hydraulic retention time of 48 h. The addition of low concentrations of oxygen (1.0 mL min^?1 of atmospheric air at 27 °C and 1 atm) assured high removal efficiencies (> 80%) for all compounds under microaerobic conditions. In fact, the applicability of this technology showed to be viable to enhance BTEX removal from contaminated waters, especially concerning benzene (with a 30% removal increase), which is a very recalcitrant compound under anaerobic conditions. However, high concentrations of ethanol adversely affected BTEX removal, especially benzene, under anaerobic and microaerobic conditions. Finally, although bacterial community richness decreased at low concentrations of ethanol, in general, the bioreactor microbiota could deal with the different operational conditions and preserved its functionality during the whole experiment.     

Partitioning in Aqueous Two-Phase Systems: Fundamentals,Applications and Trends

Over the last years, aqueous two-phase systems (ATPS) regained an increasing interest due to their potential in the downstream processing of biomolecules. After many years with only a few articles published, a lot of effort and work has been put into studying these systems for the partitioning of a range of compounds including proteins, organic low-molecular weight molecules or metal ions. Although several research and review articles appeared, a background review on ATPS partitioning fundamentals is needed. In this article, partitioning theories and main effects of several important factors for partitioning, such as molecular weight of the polymer, effect of added salts, pH, electrical charges, and temperature on phase diagrams, tie-line lengths, interfacial tension and settling time of the two aqueous phases are extensively reviewed. The trend in ATPS research is given compiling the recent 2008–2013 research articles published in the field.     

Calcium polyphosphate coacervates: effects of thermal treatment

The addition of calcium chloride eletrolyte to sodium polyphosphate solutions lead to Calcium polyphosphate coacervates. The effects of a thermal treatment were investigated with the objective to increase the relative stability of the obtained material. Thermogravimetry analysis indicates that coacervates became less hydrophilic and more thermally stable after the thermal treatment. Crystallization was identified through differential scanning calorimetry and X-ray diffraction. Morphological changes were observed after the thermal treatment by scanning electron microscopy. N₂ adsorption?Cdesorption isotherms suggest that both materials, thermally treated or not, display type IV isotherms, low superficial area and mesoporous structure. Stability experiments in solutions at different pH values show that the thermally treated calcium polyphosphate is relatively more stable than the non-treated coacervate.