Optical fibers have revolutionized telecommunications by providing higher performance, more reliable telecommunication links with ever decreasing bandwidth cost. In parallel with these developments, fiber-optic sensor technology has been a major user of technologies associated with the optoelectronic and fiber optic communications industry. Today, with the rapid advance of communications and especially sensing applications, there is an ever increasing need for advanced performance and additional functionalities. This, however, is difficult to achieve without addressing fundamental fabrication issues related to the integration onto optical fibers of advanced functional materials at the micro- and nanoscale. Solving these technical problems will open up the possibility of developing multifunctional labs integrated onto a single optical fiber, exchanging information and combining sensorial data. This could result in auto diagnostic features as well as new photonic and electro-optic functionalities useful in many strategic sectors such as optical processing, environment, life science, safety and security.
Various types of nanostructures are used in the development of nanosensors: nanoparticles, nanotubes, nanorods, two-dimensional materials like graphene, embedded nanostructures, porous silicon, and self-assembled materials. For instance, gas sensors often operate by detecting the subtle changes that deposited gas molecules make in the way electricity moves through a surface layer. Researchers have fabricated gas sensors based on carbon nanotube-based field effect transistors, which can detect electrical potential changes around them. While these and related sensing schemes can be all-electronic - i.e., not requiring optical readout - they all require sophisticated nanolithographic techniques to isolate, identify, and integrate electrical contact to the active nanosensor. Researchers have now presented a nanoscale 3D architecture that can afford highly sensitive, room temperature, rapid response, and all-electronic chemical detection.
Green Fluorescent Protein (GFP) - originally found in a jellyfish - has played a crucial role in life science research, providing insights to many fundamental questions that have paved the way to the biology and medicine of the future. Since the mid-1990s, when the protein was successfully cloned, GFP can be found in research laboratories worldwide used as a visual marker of gene expression and protein localization, easily observed via light (optical) microscopy. GFP can be linked to other proteins and is primarily used to track dynamic changes in living cells. In 2008, biologists who discovered and developed the protein as a laboratory tool won a Nobel Prize for their work. Researchers in Spain have now demonstrated how GFP can also act as an efficient nano-thermometer inside cells.
Knowing the distribution of DNA binding proteins along the genome is very informative and can tell scientists about the state of gene expression at the time of measurement. These DNA-binding proteins include transcription factors which modulate the process of transcription, various polymerases, nucleases which cleave DNA molecules, and histones which are involved in chromosome packaging in the cell nucleus. Previously, researchers demonstrated the viability of a single-molecule approach to directly visualize and map protein binding sites on DNA using fluorescent quantum dots, allowing multicolor, nanometer-resolution localization. Now, they have shown that proteins bound to DNA can be located very accurately by direct imaging. The precision of these measurement presents new opportunities for contextual genomic research on the single-molecule level.
The Venus flytrap (Dionaea muscipula) is a carnivorous plant that catches and digests little insects. Its trapping mechanism consists of a series of tiny hairs at the crease where the plant's two leaves join. When a fly or spider walk across these hairs, touching two or more of them in succession, the two leaves will close quickly enough - within hundreds of milliseconds - to prevent its escape. Now, researchers have used it as inspiration for a new biomimetic robot made with artificial muscles. The device offers promise in the development of electrically stimulated artificial muscle that could be implanted in people to help overcome muscular disease or paralysis.
Early detection of food borne pathogenic bacteria is critical to prevent disease outbreaks and preserve public health. This has led to urgent demands to develop highly efficient strategies for isolating and detecting this microorganism in connection to food safety, medical diagnostics, water quality, and counter-terrorism. Conventional techniques to detect E. coli and other pathogenic bacteria are time-consuming, labor-intensive, and inadequate as they lack the ability to detect bacteria in real time. Thus, there is an urgent need for alternative platforms for the rapid, sensitive, reliable and simple isolation and detection pathogens. Taking a novel approach to isolating pathogenic bacteria from complex clinical, environmental and food samples, researchers have developed a nanomotor strategy that involves the movement of lectin-functionalized microengines. Receptor-functionalized nanoswimmers offer direct and rapid target isolation from raw biological samples without preparatory and washing steps.
Surface-enhanced Raman spectroscopy (SERS) is a powerful research tool that is being used to detect and analyze chemicals as well as a non-invasive tool for imaging cells and detecting cancer. It also has been employed for label-free sensing of bacteria, exploiting its tremendous enhancement in the Raman signal. SERS can provide the vibrational spectrum of the molecules on the cell wall of a single bacterium in a few seconds. Such a spectrum is like the fingerprints of the molecules and therefore could be exploited as a means to quickly identify bacteria without the need of a time-consuming bacteria culture process, which typically takes a few days to several weeks depending on the species of bacteria. To practically apply SERS to the early diagnosis of bacteremia - the presence of bacteria in the blood - researchers have managed to capture bacteria in a patient's blood onto the SERS substrate.
The integration of biological components with electronics, and more specifically, the interfacing of complex biological systems is one of the current challenges on the path towards bioelectronics (or bionics for short). Up to know, and due to its technology maturity, most of the work has been done based on Si-FET technology. However, there have been some issues related to this technology which prevented a more successful implementation into real applications. Researchers have now demonstrated, for the first time, that CVD grown graphene can be employed to fabricate arrays of transistors which are able to detect the electrical activity of electrogenic cells.