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Bacterial biofilms are among the oldest and most prevalent multicellular life forms on Earth and are increasingly relevant in research areas related to industrial fouling, medicine and biotechnology. The main hurdles to obtaining definitive experimental results include time-varying biofilm properties, structural and chemical heterogeneity, and especially their strong sensitivity to environmental cues. Therefore, in addition to judicious choice of measurement tools, a well-designed biofilm study requires strict control over experimental conditions, more so than most chemical studies. Due to excellent control over a host of physiochemical parameters, microfluidic flow cells have become indispensable in microbiological studies. Not surprisingly, the number of lab-on-chip studies focusing on biofilms and other microbiological systems with expanded analytical capabilities has expanded rapidly in the past decade. In this paper, we comprehensively review the current state of microfluidic bioanalytical research applied to bacterial biofilms and offer a perspective on new approaches that are expected to drive continued advances in this field. [ABSTRACT FROM AUTHOR]

The p K values of two important drugs were determined in different binary aqueous/organic solutions, which mimic a range of industrial solvents and biological fluids encountered during drug synthesis and end use. Titrations of monoprotic (propranolol) and diprotic (atenolol) drugs were determined using a combination of potentiometric and spectroscopic methods at constant temperature and ionic strength. Single-parameter correlations between the measured p K values (at 25 °C) and hydrogen-bond acidity/basicity or solvent polarity parameters were poor in all cases. However, analysis using the multi-parameter method of Kamlet, Abboud, and Taft represents significant improvement enabling better interpretation of the solvent effects on the acid−base equilibria of the drugs. As a validation step and for a deeper understanding of the origins of the solvent effects on the drugs, all p K values were predicted by DFT calculations. Finally, acidity constants were determined by correlations between experimental and theoretical measurements. The developed method will measure and accurately simulate the effect of the solvent environment on p K values and represent advancement for questions related to drug synthesis and drug compound's behavior in biological fluids. Graphical Abstract : [ABSTRACT FROM AUTHOR]

We build on the concept of hot intrusion embossing to develop a one-step fabrication method for thermoplastic microfluidic channels containing integrated three-dimensional features. This was accomplished with simple, rapid-to-fabricate imprint templates containing microcavities that locally control the intrusion of heated thermoplastic based on their cross-sectional geometries. The use of circular, rectangular and triangular cavity geometries was demonstrated for the purposes of forming posts, multi-focal length microlense arrays, walls, steps, tapered features and three-dimensional serpentine microchannels. Process variables, such as temperature and pressure, controlled feature dimensions without affecting the overall microchannel geometry. The approach was demonstrated for polycarbonate, cycloolefin copolymer and polystyrene, but in principle is applicable to any thermoplastic. The approach is a step forward towards rapid fabrication of complex, robust, microfluidic platforms with integrated multi-functional elements. [ABSTRACT FROM AUTHOR]

The protonation constants of adenosine 5′-monophosphate, guanosine 5′-monophosphate, and inosine 5′-monophosphate were determined in binary mixtures of H2O containing 0, 10, 15, 20, 25, 30, 35, 40, 45, and 50% MeOH, using a combination of potentiometric and spectrophotometric methods at a constant temperature (25°) and constant ionic strength (0.1 mol⋅dm−3 NaClO4). The protonation constants were analyzed using the normalized polarity parameter ( E $\rm{{_{T}^{N}}}$), and Kamlet, Abboud, and Taft ( KAT) parameters. A linear correlation of log K vs. the normalized polarity parameter was obtained. Dual-parameter correlation of log K vs. π* (dipolarity/polarizability) and α (H-bond-donor acidity), as well as π* and β (H-bond-acceptor basicity) also gives good results in various aqueous organic solvent mixtures. Finally, the results are discussed in terms of the effect of solvent on the protonation equilibria. [ABSTRACT FROM AUTHOR]