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.
Applications and studies in DNA-based biophysics, biochemistry and biotechnology rely on accurate imaging with high temporal and spatial resolution towards the mesoscopic and single-molecule levels. This, in turn, relies on the ability to immobilize and stretch portions of DNA on a substrate without damaging it. Researchers in Italy have now reported a noninvasive, all-optical, holographic technique for permanently aligning liquid crystalline DNA filaments in a microperiodic template realized in soft-composite materials.
Researchers are very interested in investigating the biomechanical properties of the inner structure of cells due to their relevance in many important topics in biology such as intracellular and intercellular dynamics; tissue and organs formation and their homeostasis; but also in medicine as the formation and development of diseases like inflammatory disorders or tumor. In order to study inner cell properties, researchers have now presented a biophotonic holographic workstation that combines the complementary features of holographic optical tweezers (HOT) and self-interference digital holographic microscopy, in order to investigate biomechanics properties at the single cell level.
Fluidic force microscopy (FluidFM) is an emerging technology which combines atomic force microscopy (AFM) with microfluidics. In a new study, researchers in Switzerland have now developed an innovative method for straightforward injection into the nucleus of a living cell, taking advantage of the nanoscale accuracy and small probe size of AFM and the possibility to handle fluid under pressure-control through the integrated microchannel.
Optical tweezers offer researchers the chance to perform precise force sensing in a fluid environment. This could help to give clarity to some of the picoNewton forces that govern fundamental processes in the cell. However, currently the use of tweezers to probe biological, samples requires either direct irradiation with a laser, or the use of a tool or proxy to exert or sense very small forces. There are many instances when exposing samples to high intensity laser light is less than ideal - typically this is within a biological context. Researchers have now have shown that optical tweezers can be combined with naturally derived algae to create a stable nanoscale optical force sensor. This may enable other groups to utilize this technique to probe key force interactions that occur at the lowest end of the nanoscale force regime.
One of the key issues in the development of novel nanomedicines is the ability to track nanoscale drug carriers inside the body to evaluate where they go and how they get there. Virtually all previous preclinical studies in this area of research rely on 2D Fluorescence Reflectance Imaging (FRI). Given the limitation of 2D FRI in not being able to detect the fluorescence in deep-seated organs and tissues, 3D Fluorescence Molecular Tomography (3D FMT) emerged as an alternative. However, the lack of anatomical information was an important barrier hindering the routine use of standard 3D FMT for in vivo imaging of nanomedicines. Researchers have now developed a hybrid CT-FMT-based imaging protocol to enable more meaningful and more quantitative in vivo analyses.