Supersensitive fingerprinting of explosives by chemically modified nanosensors arrays.

The capability to detect traces of explosives sensitively, selectively and rapidly could be of great benefit for applications relating to civilian national security and military needs. Here, we show that, when chemically modified in a multiplexed mode, nanoelectrical devices arrays enable the supersensitive discriminative detection of explosive species. The fingerprinting of explosives is achieved by pattern recognizing the inherent kinetics, and thermodynamics, of interaction between the chemically modified nanosensors array and the molecular analytes under test. This platform allows for the rapid detection of explosives, from air collected samples, down to the parts-per-quadrillion concentration range, and represents the first nanotechnology-inspired demonstration on the selective supersensitive detection of explosives, including the nitro- and peroxide-derivatives, on a single electronic platform. Furthermore, the ultrahigh sensitivity displayed by our platform may allow the remote detection of various explosives, a task unachieved by existing detection technologies.

Computed tomography of Lipiodol-loaded biodegradable pasty polymer for implant visualization.

Targeted delivery of drug-loaded implants for regional drug therapy has become an important approach to therapy. Simple and reproducible imaging methodologies to evaluate the implant noninvasively are needed. The goal of this work was to noninvasively evaluate the visibility, shape and degradation of a biodegradable implant containing Lipiodol (an X-ray contrast medium) by computed tomography (CT). For in vitro evaluation, Lipiodol was incorporated in poly(sebacic-co-ricinoleic acid) [P(SA:RA)], a biodegradable injectable pasty polymer, and CT visibility was assessed. For ex vivo evaluation, bovine liver was injected with the polymer-loaded Lipiodol; for in vivo evaluation rats were injected subcutaneously with Lipiodol in polymer and CT was performed. We show that polymer diameter at CT correlates with implant weight and pathological measurements. Polymer formulation containing 5% Lipiodol was visible on CT in vitro. Ex vivo tests showed a round polymer deposit at the injection site compared with free dispersion of Lipiodol alone. Correlation between implant size at CT scan and surgery at 48 h was R(2) = 0.78. Average CT diameter at 9 days was 14.2 ± 2.8 mm in rats injected with Lipiodol in the polymer formulation, as compared with 7.3 ± 1.1 mm in controls. After 9 days, the implant degraded into several zones containing inflammatory cells seen on CT as areas with increased heterogeneity. In conclusion, Lipiodol incorporated in P(SA:RA) is visible on CT, and polymer degradation can potentially be monitored noninvasively. This method can be widely applied to follow changes in biodegradable implants.

Unwrapping core-shell nanowires into nanoribbon-based superstructures.

A prize for the ribbons: High-quality crystalline semiconducting nanoribbons can be prepared by "unwrapping" core-shell nanowire precursors. For example, Ge nanowires were coated with a Si shell and the top surface was carved by etching whereas the sides were protected by a thin layer of photoresist material. Finally the Ge core was removed selectively by chemical means to give fully opened and flat nanoribbon structures.