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This paper demonstrates that the gas-filled compartments in the packing material commonly called “bubble wrap” can be repurposed in resource-limited regions as containers to store liquid samples, and to perform bioanalyses. The bubbles of bubble wrap are easily filled by injecting the samples into them using a syringe with a needle or a pipet tip, and then sealing the hole with nail hardener. The bubbles are transparent in the visible range of the spectrum, and can be used as “cuvettes” for absorbance and fluorescence measurements. The interiors of these bubbles are sterile and allow storage of samples without the need for expensive sterilization equipment. The bubbles are also permeable to gases, and can be used to culture and store micro-organisms. By incorporating carbon electrodes, these bubbles can be used as electrochemical cells. This paper demonstrates the capabilities of the bubbles by culturing E. coli, growing C. elegans, measuring glucose and hemoglobin spectrophotometrically, and measuring ferrocyanide electrochemically, all within the bubbles., Chemistry and Chemical Biology, Other Research Unit

The fabrication and properties of “fluoroalkylated paper” (“\(R^F\) paper”) by vapor-phase silanization of paper with fluoroalkyl trichlorosilanes is reported. \(R^F\) paper is both hydrophobic and oleophobic: it repels water \((θ_{app}^{H2O} > 140^{\circ})\), organic liquids with surface tensions as low as \(28 \space mN \space m^{-1}\), aqueous solutions containing ionic and non-ionic surfactants, and complex liquids such as blood (which contains salts, surfactants, and biological material such as cells, proteins, and lipids). The propensity of the paper to resist wetting by liquids with a wide range of surface tensions correlates with the length and degree of fluorination of the organosilane (with a few exceptions in the case of methyl trichlorosilane-treated paper), and with the roughness of the paper. \(R^F\) paper maintains the high permeability to gases and mechanical flexibility of the untreated paper, and can be folded into functional shapes (e.g., microtiter plates and liquid-filled gas sensors). When impregnated with a perfluorinated oil, \(R^F\) paper forms a “slippery” surface (paper slippery liquid-infused porous surface, or “paper SLIPS“) capable of repelling liquids with surface tensions as low as \(15 \space mN \space m^{-1}\). The foldability of the paper SLIPS allows the fabrication of channels and flow switches to guide the transport of liquid droplets., Chemistry and Chemical Biology, Other Research Unit

The mechanism (or mechanisms) of enthalpy–entropy (H/S) compensation in protein–ligand binding remains controversial, and there are still no predictive models (theoretical or experimental) in which hypotheses of ligand binding can be readily tested. Here we describe a particularly well-defined system of protein and ligands—human carbonic anhydrase (HCA) and a series of benzothiazole sulfonamide ligands with different patterns of fluorination—that we use to define enthalpy/entropy (H/S) compensation in this system thermodynamically and structurally. The binding affinities of these ligands (with the exception of one ligand, in which the deviation is understood) to HCA are, despite differences in fluorination pattern, indistinguishable; they nonetheless reflect significant and compensating changes in enthalpy and entropy of binding. Analysis reveals that differences in the structure and thermodynamic properties of the waters surrounding the bound ligands are an important contributor to the observed H/S compensation. These results support the hypothesis that the molecules of water filling the active site of a protein, and surrounding the ligand, are as important as the contact interactions between the protein and the ligand for biomolecular recognition, and in determining the thermodynamics of binding., Chemistry and Chemical Biology

Auf das Wasser kommt es an: Konservierte Bindungsgeometrie, enthalpiegetriebene Bindungsweise und nichtunterscheidbare Bindungsaffinitäten für fluorierte und nichtfluorierte Liganden von humaner Carbonsäureanhydrase (siehe Bild) stützen die Theorie, dass das Schlüssel-Schloss-Modell einen wichtigen Bestandteil des Bindungsvorgangs unbeachtet lässt: das Wasser, das die Bindungstasche des Proteins füllt und den Liganden umgibt., Chemistry and Chemical Biology