The realization of a three-dimensional atomic force microscopy portends exciting research directions across nanoscience and nanotechnology. Demonstrations to date have been limited by the indirect means that are required to extract a three-dimensional force vector from the traditional 1D observable in AFM (i.e., cantilever deflection). Existing 3D AFM techniques require recording thousands of frequency shift curves at different lateral locations followed by off-line integration (to yield energy) and lateral differentiation (to yield lateral force). This procedure is inherently slow. In new work, researchers now report 3D force measurements based on a 3D local observable, rather than on cantilever deflection alone.
Optical imaging of nanoscale objects, whether it is based on scattering or fluorescence, is a challenging task due to reduced detection signal-to-noise-ratio and contrast at sub-wavelength dimensions. While advances in light microscopy have led to techniques that can image individual nanoparticles, these methods rely on relatively sophisticated and expensive microscopy systems. Researchers have now created a field-portable fluorescence microscopy platform installed on a smartphone for imaging of individual nanoparticles as well as viruses using a light-weight and compact opto-mechanical attachment to the existing camera module of the cellphone.
Direct visualization and manipulation of individual carbon nanotubes (CNTs) in ambient conditions is of great significance for their characterizations and applications. However, the direct visualization, location, and manipulation of individual CNTs is extremely difficult due to their nanoscale diameters. The observation of individual CNTs usually requires electron microscopes under high vacuum. Researchers now have proposed a facile way to realize optical visualization of individual carbon nanotubes and, based on that, macroscale manipulation of individual carbon nanotubes that could be carried out under an optical microscope.
While nanoparticles are emerging as drug carriers for targeted nanomedicines, preclinical assays to test nanoparticle efficacy are hampered by the lack of methods to quantitatively determine internalized particles. A novel method is suited to pave the way for preclinical testing of nanoparticles to establish dose-efficacy relationships and to optimize biophysical and biochemical parameters in order to make better drug delivery vehicles. The team demonstrated that it is possible to determine the exact number of nanoparticles inside a cell through a combination of three methods and a mathematical model which they developed to link the data from these three methods.
Ferromagnetic materials exhibit the so-called anomalous Hall effect (AHE), whereby the electrons flowing through the material experience a lateral force pushing them to one side as a result of the material's intrinsic magnetization. Although the AHE has been used in the field on nanotechnology to measure the magnetic behavior of nanoparticles (with sizes larger than 50 nm), nobody so far had tried to separate the signals of the individual particles. Researchers in Germany have now developed a simple technique which allows to measure the magnetic response of single ferromagnetic nanoparticles down to a radius of about 3.3 nm.
Nanopores are an exciting class of single molecule nanosensors. For several years now, nanopore technology has been developed as a biosensor at the single-molecule resolution to detect an array of biomedical molecules, such as DNA, RNA, protein, biotoxin, and various nanopore projects have been funded to develop the next generation of DNA sequencing technology. The sensing principle is based on the resistive pulse technique - molecules are detected as they pass through a single nanopore since during translocation the molecules exclude ions and therefore modulate the current. In new work, researchers have demonstrated the single molecule detection of a wide range of proteins with solid state glass nanopores.
For a transistor to work properly, it must contain impurity atoms - called dopants - replacing the silicon atoms at certain places in the device. Given that modern transistor are approaching the atomic scale, the exact location of a single dopant atom becomes critical in determining the device functionality. In a different context, single dopant atoms in semiconductors have now proved to be an excellent platform to encode quantum information. Therefore, the exact location of single dopant atoms is also crucial to future quantum computers based on silicon. A new technique allows the accurate location of a single dopant atom in a nanoscale device, after the device has been fabricated, and without damaging or altering any of its functionalities.
Most of the research efforts on developing synthesis methods for graphene has focused on flat substrates. However, direct growth of graphene layers on prepatterned substrates has remained elusive. In new work, resarchers have grown graphene in prepatterned copper-coated substrates, and they apply this protocol for the fabrication of MEMS devices, in particular, atomic force microscope probes. This layer of graphene improves the functionality of the probes by making them conductive and more resistant to wear.