Jason B. Shear

Multi-shell microspheres with integrated chomatographic and detection layers for use in array sensors

The development of miniaturized chromatographic systems localized within individual polymer microspheres and their incorporation into a bead-based cross-reactive sensor array platform is reported. The integrated chromatographic and detection concept is based on the creation of distinct functional layers within the microspheres. In this first example of the new methodology, complexing ligands have been selectively immobilized to create separation layers harboring an affinity for various metal cations. Additionally, a broadly responsive compleximetric dye is used to yield the detection layers that exhibit optical responses in the presence of a wide range of metal cations. Information concerning the identities and concentrations of solution-dissolved metal cations can be drawn from the temporal properties of the beads optical responses. Varying the nature of the ligand in the separation shell yields a collection of cross-reactive sensing elements well-suited for use in array-based micrototal analysis systems. Accordingly, such beads have been incorporated into the Electronic Taste Chip platform and used for discriminating among aqueous metal cation solutions.

Analysis of neuropeptides using capillary zone electrophoresis with multichannel fluorescence detection

Capillary zone electrophoresis is fast becoming one of the most sensitive separation schemes for sampling complex microenvironments. A unique detection scheme is developed in which a charge-coupled device (CCD) detects laser induced fluorescence from an axially illuminated electrophoresis capillary. The fluorescence from an analyte band is measured over a several centimeter section of the capillary, greatly increasing the observation time of the fluorescently tagged band. The sensitivity of the system is in the 1-8 X 10-20 mol range for derivatized amino acids and peptides. Subattomole quantities of bag cell neuropeptides collected from the giant marine mollusk Aplysia californica can be measured.