High-aspect-ratio gold nanorods: their synthesis and application to image cell-induced strain fields in collagen films.

Gold nanoparticles are receiving considerable attention due to their novel properties and the potential variety of their uses. Long gold nanorods with dimensions of approximately 20 × 400 nm exhibit strong light scattering and can be easily observed under dark-field microscopy. Here we describe the use of this light-scattering property to track micrometer scale strains in collagen gels and thick films, which result from cell traction forces applied by neonatal heart fibroblasts.

Formation of PbS nanowire pine trees driven by screw dislocations.

The basic characteristics of nanowire growth driven by screw dislocations were investigated by synthesizing hierarchical lead sulfide (PbS) nanowire "pine trees" using chemical vapor deposition of PbCl(2) and S precursors and systematically observing the effects of various growth parameters, such as hydrogen flow, temperature, pressure, and the growth substrates employed. Statistical surveys showed that the growth rate of the dislocation-driven trunk is about 6 mum/min and that of the vapor-liquid-solid (VLS) driven branch nanowire is about 1.2 mum/min under the typical reaction conditions at 600 degrees C, 900 Torr, and a hydrogen flow rate of 1.