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Single-molecule fluorescence spectroscopy has allowed many chemical and biological systems to be studied both in vitro and in vivo. However, it is difficult to perform such measurements at temperatures above 37â°C because the index-matching fluids used to direct light from the sample to the lens can also conduct heat, and this heating can damage the lens. Now Jerrod Schwartz, Stavros Stavrakis and Stephen Quake have shown that a colloidal titanium dioxide particle can act as a microlens when placed next to an emitting molecule. This microlens focuses light from the molecule into a conventional lens that is separated from the sample by air, which allows single-molecule measurements to be performed on biological systems in real time at temperatures as high as 70â°C. This image is based on a simulation showing how light from a point source is focused by the microlens.
The food industry will only reap the benefits of nanotechnology if issues related to safety are addressed and companies are more open about what they are doing.
An online survey shows that most researchers do not use suitable personal and laboratory protection equipment when handling nanomaterials that could become airborne.
Placing colloidal spheres in the immediate proximity of fluorescent molecules makes it possible to achieve single-molecule imaging at high temperatures with a low-cost system.
An atomic force microscope can probe both the surface and subsurface regions of a sample by exploiting nanomechanical coupling between the probe and the sample.
Nanoparticles can be assembled into superlattices and dimer clusters using a reconfigurable DNA device that also allows interparticle distances to be modified, post-assembly, in response to molecular stimuli.
Gold nanoparticles can be assembled into ordered arrays through the site-selective deposition of mesoscopic DNA origami onto lithographically patterned substrates and the precise binding of gold nanocrystals to each DNA structure.
A single dopant atom can dominate the subthreshold behaviour of a field-effect transistor, and this effect is enhanced if the atom is located near a dielectric.
A biosensor containing a microfluidic purification chip that supplies a downstream nanoribbon-detector can detect disease biomarkers in samples of whole blood.
Steps in the electrostatic potential at domain walls in a ferroelectric material give rise to a new kind of photovoltaic effect that produces voltages significantly higher than the bandgap of the material.
Nanoscale filaments with a Magnéli structure are shown to be responsible for resistance switching in thin films of TiO2, and the properties of the filaments are directly observed during the switching process.
The adhesion of single DNA molecules on modified gold surfaces can be adjusted by surface potential, and the desorption forces of these interactions are measured by single-molecule force spectroscopy.
Asymmetric salt concentrations can be used to enhance the capture rate of DNA in solid-state nanopores and detect picomolar solutions of unlabelled DNA.