Cell electrophoretic mobility (EPM) can be used to characterize individual cells. The purpose of this study is to establish reproducible and reliable cell EPM values obtained using microcapillary electrophoresis (microCE) chips. We studied cell electrophoresis on microCE chips through the comprehensive measurement of EPM and zeta potential. The inner wall of microchannels in microCE chips was coated with three kinds of reagents, namely bovine serum albumin (BSA), gelatin, and 2-methacryloyloxyethylphosphorylcholine (MPC) polymer to prevent nonspecific adhesion and interaction between cells and the inner wall. Electrophoresis was conducted in phosphate-buffered saline (pH 4-9) using erythrocytes extracted from sheep whole blood. Electroosmotic flow (EOF) mobility was measured using noncharged particles, and then the true EPM was calculated by subtracting the EOF mobility from the electromigration. MPC polymer coatings in microCE chips reduced the zeta potential of the inner wall and fully prevented nonspecific adhesion. EPM data obtained using microCE chips were almost the same and reproducible over a wide range of pH irrespective of the coating reagent used. In conclusion, reliability in the measurement of cell EPM using microCE chips was realized.
Despite the name, rare earth elements are relatively abundant in soil. Therefore, these elements might interact with biosphere during the history of life. In this study, we have examined the effect of rare earth ions on the growth of bacteria, fungi and soil nematode. All rare earth ions, except radioactive promethium that we have not tested, showed antibacterial and antifungal activities comparable to that of copper ions, which is widely used as antibacterial metals in our daily life. Rare earth ions also have nematicidal activities as they strongly perturb the embryonic development of the nematode, Caenorhabditis elegans. Interestingly, the nematicidal activity increased with increasing atomic number of lanthanide ions. Since the rare earth ions did not show high toxicity to the human lymphoblastoid cell line or even stimulate the growth of the cultured cells at 1 mM, it raised the possibility that we can substitute rare earth elements for the antibacterial metals usually used because of their safety.
Novel fluorescent probes have been developed for the ultratrace detection of heavy metal ions by capillary electrophoresis using laser-induced fluorescence detection. Based on a molecular design, the probes are composed of an octadentate chelating moiety, a macrocyclic DOTA (tetraazacyclododecanetetraacetic acid) and an acyclic DTPA (diethylenetriaminepentaacetic acid) frame, a spacer and a fluorophore (fluorescein). These were chosen on the basis of their ability to form kinetically inert and highly emissive complexes, and to prevent a quenching effect even with heavy and paramagnetic metal ions. Addition of a cationic polymer, polybrene, in the separation buffer provided high resolution and simultaneous detection of Ca(2+), Mg(2+), Cu(2+), Zn(2+), Ni(2+), Co(2+), Mn(2+), Cd(2+) and Pb(2+). The direct fluorescence detection of these metal ions with high sensitivity at lower ppt levels, typically 2-7 × 10(-11) M (potentially sub-ppt), was successfully achieved. While separation of anionic compounds using a counter cation ("Ion Association (IA)" mode) is typically controlled by the ion association equilibrium constants, K(ass), it was found that differences in the mobilities, µ(ep(IAC)), of the ion association complexes formed between the probe complexes and counter cations are the driving forces for separation in this new method. This suggests that each of the polybrene-probe complexes has different chemical structures among metal ions, which were able to be determined by CD spectra in this investigation. This novel separation mode was termed the "Ion Association Complex (IAC)" mode, distinct from the IA mode.
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