The transport behavior of lambda-DNA (48 kbp) in fused silica nanoslits is investigated upon application of electrical fields of different strengths. The slit dimensions are 20 nm in height, 3 microm in width, and 500 microm in length. With fields of 30 kV/m or below, the molecules move fluently through the slits, while at higher electrical fields, the DNA molecules move intermittently, resulting in a strongly reduced mobility. We propose that the behavior can be explained by mechanical and/or field-induced dielectrophoretic DNA trapping due to the surface roughness in the nanoslits. The observation of preferential pathways and trapping sites of the lambda-DNA molecules through the nanoslits supports this hypothesis and indicates that the classical viscous friction models to explain the DNA movement in nanoslits needs to be modified to include these effects. Preliminary experiments with the smaller XbaI-digested litmus-DNA (2.8 kbp) show that the behavior is size-dependent, suggesting that the high field electrophoresis in nanoslits can be used for DNA separation.

Monodisperse liquid particles (femtolitre oil droplets) are shown to self-organize into three-dimensional (3D) close-packed face-centered cubic (fcc) arrangements. Droplets were formed at a nanochannelmicrochannel interface, and the formation of these arrangements occurred at certain flow-rate ratios of oil and water. The remarkably robust and stable structures formed in two different 'crystallographic' orientations of a face-centered cubic lattice, fcc(100) and fcc(111), as evidenced by the occurrence of square and hexagonal patterns at the plane adjacent to the channel wall. The orientation was found to depend on the oil-to-water flow-rate ratio. Similar to solid state crystals, 'crystallographic' features were observed, such as dislocation lines and defects. The 3D arrays presented in this work could provide platforms for a number of applications.

We present an electrokinetic label-free biomolecular screening chip (Glass/PDMS) to screen up to 10 samples simultaneously using surface plasmon resonance imaging (iSPR). This approach reduces the duration of an experiment when compared to conventional experimental methods. This new device offers a high degree of parallelization not only for analyte samples, but also for multiplex analyte interactions where up to 90 ligands are immobilized on the sensing surface. The proof of concept has been demonstrated with well-known biomolecular interactant pairs. The new chip can be used for high throughput screening applications and kinetics parameter extraction, simultaneously, of interactant-protein complex formation.

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