Intact mammalian cell function on semiconductor nanowire arrays: new perspectives for cell-based biosensing.

Nanowires (NWs) are attracting more and more interest due to their potential cellular applications, such as delivery of compounds or sensing platforms. Arrays of vertical indium-arsenide (InAs) NWs are interfaced with human embryonic kidney cells and rat embryonic dorsal root ganglion neurons. A selection of critical cell functions and pathways are shown not to be impaired, including cell adhesion, membrane integrity, intracellular enzyme activity, DNA uptake, cytosolic and membrane protein expression, and the neuronal maturation pathway. The results demonstrate the low invasiveness of InAs NW arrays, which, combined with the unique physical properties of InAs, open up their potential for cellular investigations.

Injection molded nanofluidic chips: fabrication method and functional tests using single-molecule DNA experiments.

We demonstrate that fabrication of well-defined nanofluidic systems can be greatly simplified by injection molding of thermoplastic polymers. Chips featuring nanochannel arrays, microchannels and integrated interconnects are produced in a single processing step by injection molding. The resulting open channel structures are subsequently sealed by facile plasma-enhanced thermal bonding of a polymer film. This fast, inexpensive and industry-compatible method thus provides a single-use all-polymer platform for nanofluidic lab-on-a-chip applications. Its applicability for nanofluidics is demonstrated by DNA stretching experiments performed on individual double-stranded DNA molecules confined in the injection molded nanochannels. The obtained results are consistent with measurements performed in costly state-of-the-art silica nanochannels, for both straight and tapered channel geometries.

Nanoelectromechanical coupling in fullerene peapods probed by resonant electrical transport experiments.

Fullerene peapods, which are carbon nanotubes encapsulating fullerene molecules, can offer enhanced functionality with respect to empty nanotubes. Their prospective applications include, for example, data storage devices, single-electron transistors and spin-qubit arrays for quantum computing. However, the present incomplete understanding of how a nanotube is affected by entrapped fullerenes is an obstacle for peapods to reach their full potential in nanoscale electronic applications. In this paper, we investigate the effect of C(60) fullerenes on low-temperature electron transport through peapod quantum dots. Compared with empty nanotubes, we find an abnormal temperature dependence of Coulomb blockade oscillations, indicating the presence of a nanoelectromechanical coupling between electronic states of the nanotube and mechanical vibrations of fullerenes. This provides a method to detect the C(60) presence and to probe the interplay between electrical and mechanical excitations in peapods, which thus emerge as a new class of nanoelectromechanical systems.

Confinement spectroscopy: probing single DNA molecules with tapered nanochannels.

We demonstrate a confinement spectroscopy technique capable of probing small conformational changes of unanchored single DNA molecules in a manner analogous to force spectroscopy, in the regime corresponding to femtonewton forces. In contrast to force spectroscopy, various structural forms of DNA can easily be probed, as indicated by experiments on linear and circular DNA. The extension of circular DNA is found to scale according to the de Gennes exponent, unlike for linear DNA.