Surface-enhanced Raman scattering (SERS) offers enormous potential for chemical sensing, even though the large nonlinearity of the effect makes reproducible sensing difficult. SERS relies upon a fundamental phenomenon in physics called the Raman effect - the change in the frequency of monochromatic light, such as a laser, when it passes through a substance. Properly harnessed, Raman scattering can identify specific molecules by detecting their characteristic spectral fingerprints. A novel DNA-based assembly technique developed by scientists in South Korea now offers a means of precise engineering of gap distances in nanoparticle dumbbells for a robust surface-enhanced Raman sensing of DNA and RNA molecules.
Since its invention in 1986 by Binnig, Quate, and Gerber, the atomic force microscope (AFM) has become an indispensable tool for investigators in the physical, materials, and biological sciences. The AFM quickly gained acceptance in these fields due to its ability to capture topographical maps of surfaces in either air or liquid with sub-angstrom and nanometer resolution. This Application Note briefly describes the basics of both optical and atomic force microscopy, followed by a discussion of some of the technical challenges of integrating these two distinct imaging modalities. In certain cases, the benefits and disadvantages of different approaches to design and integration are discussed. Lastly, a few examples of successful application of these combined imaging modalities are presented.
A scarcity of empirical data - especially regarding losses - hampers nanotechnology-related risk dialogue. Nanotechnology is a growing niche, so there is little litigation or loss history to analyze. Thus, much of the discussion of nanotechnology and its management flows from hypothetical examples. Less murky is the fact that nanotechnology is not a passing fad. It has innovative applications for a range of technologies and sectors, including drug delivery, medical imaging, integrated sensors, and semiconductors. The biggest areas of nanotechnology risk management concerns lies in workers' compensation and product liability. This article looks at industry responses and risk management strategies.
Graphene based sheets such as pristine graphene, graphene oxide, or reduced graphene oxide are basically single atomic layers of carbon network. They are the world's thinnest materials. A general visualization method that allows quick observation of these sheets would be highly desirable as it can greatly facilitate sample evaluation and manipulation, and provide immediate feedback to improve synthesis and processing strategies. Current imaging techniques for observing graphene based sheets include atomic force microscopy, transmission electron microscopy, scanning electron microscopy and optical microscopy. Some of these techniques are rather low-throughput. And all the current techniques require the use of special types of substrates. This greatly limits the capability to study these materials. Researchers from Northwestern University have now reported a new method, namely fluorescence quenching microscopy, for visualizing graphene-based sheets.
As the fields of bionanotechnologies develop, it will become possible one day to use biological nanodevices such as nanorobots for in situ and real-time in vivo diagnosis and therapeutic intervention of specific targets. A prerequisite for designing and constructing wireless biological nanorobots is the availability of an electrical source which can be made continuously available in the operational biological environment (i.e. the human body). Several possible sources - temperature displacement, kinetic energy derived from blood flow, and chemical energy released from biological motors inside the body - have been designed to provide the electrical sources that can reliably operate in body. Researchers now report the construction of a 980-nm laser-driven photovoltaic cell that can provide a sufficient power output even when covered by thick biological tissue layers.
Ultrathin nanosieves with a thickness smaller than the size of the pores are especially advantageous for applications in materials separation since they result in an increase of flow across the nanosieve. Separation of complex biological fluids can particularly benefit from novel, chemically functionalized nanosieves, since many bioanalytical problems in proteomics or medical diagnostics cannot be solved with conventional separation technologies. Researchers in Germany have now fabricated chemically functionalized nanosieves with a thickness of only 1 nm - the thinnest free-standing nanosieve membranes that have been reported so far. The size of the nanoholes in the membranes can be flexibly adjusted down to 30 nm by choosing appropriate conditions for lithography.
Safe drinking water has been and increasingly will be a pressing issue for communities around the world. In developed countries it is about keeping water supplies safe while in the rest of the world it is about making it safe. The potential impact areas for nanotechnology in water applications are divided into three categories - treatment and remediation, sensing and detection, and pollution prevention. Within the category of sensing and detection, of particular interest is the development of new and enhanced sensors to detect biological and chemical contaminants at very low concentration levels. Testing of water against a spectrum of pathogens can potentially reduce the likelihood of many diseases from cancer to viral infections.
The key for most visionary electronic applications will be printability, i.e. that the circuits can be applied to any material, and flexibility, i.e. that they can adhere to any shape or form - even body parts. Imagine an ultrathin film of electronic circuits attached to internal organs like your heart to monitor vital functions. All existing forms of electronics are built on the two-dimensional, planar surfaces of either semiconductor wafers or plates of glass. Mechanically flexible circuits based on organic semiconductors are beginning to emerge into commercial applications, but they can only be wrapped onto the surfaces of cones or cylinders - they cannot conform to spheres or any other type of surface that exhibits non-Gaussian curvature. Applications that demand conformal integration, e.g. structural or personal health monitors, advanced surgical devices, or systems that use ergonomic or bio-inspired layouts, etc., require circuit technologies in curvilinear layouts.