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MEETING NEWS 15th International Symposium on Microscale Separations and Analysis (HPCE 2002)—Judith Handley reports from Stockholm, Sweden
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Rapid single-cell analysis on a microfluidic chip Christopher Culbertson, J. Michael Ramsey, and their colleagues at Oak Ridge National Laboratory have fabricated a fast, new, reliable microfluidic device scaled for single-cell analysis. The device, currently in the testing stage, is the result of a project proposed to them by Nancy Allbritton at the University of California–Irvine to study the development of cancer, says Culbertson. To evaluate the system and show that a cell can be loaded with a substance, the team placed fluorescent Oregon green and carboxyfluorescein dyes into the cytosol. Although the device successfully lysed cells and separated the cellular membrane from the other components, Culbertson says that the fluorescence detector showed four peaks instead of the single peak expected from the intracellular hydrolysis of Oregon green. A probable explanation, he says, is that some cells undergo a physiologically different metabolism, which means that the cells were unexpectedly heterogeneous. Detecting hydrolyzed dye products bodes well for the future of the project— the study of unusual kinase activity, which has been implicated in cancer. Instead of dyes, Culbertson says, the researchers will load cells with kinase substrates and study the influence of kinase on cell regulation. The automated lysis and analysis microsystem is about 1000 times faster than ∆P
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Figure not available for use on the Web. 100 µm
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conventional CE, and electropherograms are very similar for both methods. The design can be modified to perform parallel analyses on the same chip.
Analyte-tunable, in situ monolithic columns What chemist wouldn’t want an easy-tomake CE column that can be tailored to different analytes, performs good separations, and has been tested both in preparative capillary columns and on analytical microchips? In separate work, Maria Dulay, Richard Zare, and colleagues at Stanford University and Anup Singh and co-workers at Sandia National Laboratories–California have developed reversedphase, stationary, monolithic columns that require no frits and can be polymerized on-chip by UV irradiation. Dulay’s group tailors the hydrophobicity of a polymerized sol–gel column to specific analytes by bonding organic alkyl chains, aromatic groups, or amines with inorganic silanol groups on the monolithic surface. They regulate the pore size by the ratio of solvent to monomers in the polymerization mixture. More toluene increases pore size, and less decreases porosity. Dulay says that the inorganic–organic nature of their capillary material is what “sets it apart from other monolithic structures used in [capillary electrochromatography]. Those are purely organic.” Their column can be prepared in
