We present a model that quantitatively describes the performance of microfabricated electrophoretic devices filled with linear polyacrylamide as replaceable sieving material for single-stranded DNA analyses. The dependence of resolution on various separation parameters such as selectivity, diffusion, injector size, device length, and channel folding was investigated. A previously predicted dependence of longitudinal diffusion coefficient on electric field strength has been verified. We have used this model to develop and optimize microfabricated electrophoretic devices for DNA analyses. For single-color DNA sequencing mixtures, we routinely achieve separations of 400 bases in under 14 min at 200 V/cm, and separation of 350 bases in only 7 min at 400 V/cm, with a minimum resolution of R = 0.5. Our results also indicate reduced fragment biasing and efficient sample stacking for DNA sample loading on microfabricated devices.

We developed a deep-ultraviolet (UV) microscope capable of imaging cell mitosis and motility at 280 nm for 45 min with minimal UV-induced toxicity, and for 6 h before the onset of visible cell death in cultured human and mouse cells. Combined with computational methods that convert the intensity of each pixel into an estimate of mass, deep-UV microscopy images generate maps of nucleic acid mass, protein mass and fluorescence yield in unlabeled cells.

A parallel microfluidic cytometer (PMC) uses a high-speed scanning photomultiplier-based detector to combine low-pixel-count 1-D imaging with flow cytometry. The 384 parallel flow channels of the PMC decouple count rate from signal-to-noise ratio. Using 6-pixel 1-D images, we investigated protein-localization in a yeast model for a human protein-misfolding disease and demonstrated the feasibility of a nuclear-translocation assay in Chinese-hamster-ovary (CHO) cells expressing a NFκB-GFP reporter.

We report the development of a practical ultrafast allelic profiling assay for the analysis of short tandem repeats (STRs) by using a highly optimized microf luidic electrophoresis device. We have achieved baselineresolved electrophoretic separations of single-locus STR samples in 30 sec. Analyses of PCR samples containing the four loci CSF1PO, TPOX, THO1, and vWA (abbreviated as CTTv) were performed in less than 2 min. This constitutes a 10-to 100-fold improvement in speed relative to capillary or slab gel systems. The separation device consists of a microfabricated channel 45 m ؋ 100 m in cross section and 26 mm in length, filled with a replaceable polyacrylamide matrix operated under denaturing conditions at 50°C. A f luorescently labeled STR ladder was used as an internal standard for allele identification. Samples were prepared by standard procedures and only 4 l was required for each analysis. The device is capable of repetitive operation and is suitable for automated high-speed and high-throughput applications.