The use of design concepts adapted from nature is a promising new route to the development of advanced materials. There are quite a number of terms such as biomimetics, biognosis, biomimicry, or even 'bionical creativity engineering' that refer to more or less the same thing: the application of methods and systems found in nature to the study and design of engineering systems and modern technology. And increasingly, nanotechnology researchers find naturally occurring nanostructures a useful inspiration for overcoming their design and fabrication challenges. Because biological structures are the result of millennia of evolution, their designs possess many unique merits that would be difficult to achieve by a completely artificial simulation. By replicating the eye of a fruit fly, researchers have now demonstrated a highly reliable and low-cost technique for making inorganic replicas of biotemplates for fabricating complex nanostructures with biologically inspired functionality.
Much is being written about nanotechnology's role in vastly improving the detection and treatment of cancer. Detection of cancer at the earliest stage provides the greatest chance of survival. Unfortunately, cancer has a logarithmic growth rate. A one cubic centimeter size tumor may have 40-50 cell divisions and typically doctors don't see 80% of the life of a tumor. The detection of a protein pattern in blood serum can be helpful in evidencing a possible presence of cancer at an early stage. The problem is that 'early' means the capability of detecting very few molecules in dilute conditions. Now, in another step to improve the design and fabrication of devices for single molecule detection, new research has demonstrated an experimental capability of detecting down to as few as 10 organic molecules deposited on a quantum dot.
One term you hear quite often in discussion about the potential risks of nanotechnology is 'precautionary principle'. This moral and political principle, as commonly defined, states that if an action or policy might cause severe or irreversible harm to the public or to the environment, in the absence of a scientific consensus that harm would not ensue, the burden of proof falls on those who would advocate taking the action. The principle aims to provide guidance for protecting public health and the environment in the face of uncertain risks, stating that the absence of full scientific certainty shall not be used as a reason to postpone measures where there is a risk of serious or irreversible harm to public health or the environment. In 2001, an expert panel commissioned by the European Environment Agency (EEA) published a report, Late Lessons from Early Warnings: The Precautionary Principle 1896-2000, which explored 14 case studies, all of which demonstrated how not heeding early warnings had led to a failure to protect human health and the environment. It looked at controversial topics such as asbestos, Mad Cow Disease, growth hormones, PCBs and radiation - all of which demonstrated how not heeding early warnings had led to a failure to protect human health and the environment. The expert group that compiled the EEA report identified 12 'late lessons' on how to avoid past mistakes as new technologies are developed. These lessons bear an uncanny resemblance to many of the concerns now being raised about various forms of nanotechnology.
Modern medicine would be unthinkable without biomedical implants. The market for medical implant devices in the U.S. alone is estimated to be $23 billion per year and it is expected to grow by about 10% annually for the next few years. Implantable cardioverter defibrillators, cardiac resynchronization therapy devices, pacemakers, tissue and spinal orthopedic implants, hip replacements, phakic intraocular lenses and cosmetic implants will be among the top sellers. Current medical implants, such as orthopedic implants and heart valves, are made of titanium and stainless steel alloys, primarily because they are biocompatible. Unfortunately, a common complication associated with medical implants results from infectious biofilms which may cause chronic infection that is difficult to control. For instance, biofilms are present on the teeth as dental plaque, where they may become responsible for tooth decay and gum disease. Because teeth are easily accessible, removing plaque is not a problem. If biofilms develop on medical implants deep inside the body, though, they can become a serious, sometimes life-threatening problem. Preventing or limiting the formation of bacterial biofilm on the surface of implanted medical devices is an important approach to control bacterial biofilm-related infections. A new study demonstrates the effectiveness of a process combining surface nanocrystallization and thermal oxidation for reducing the biofilm's adherence to stainless steel.
Any drug intended for systemic administration and all medical devices which will contact blood must undergo thorough biocompatibility testing. These tests include an in vitro assay to determine the material's potential to damage red blood cells (hemolysis). Hemolysis, the abnormal breakdown of red blood cells either in the blood vessels (intravascular hemolysis) or elsewhere in the body (extravascular), can lead to anemia or other pathological conditions. In the pharmaceutical industry, hematocompatibility testing is harmonized through the use of internationally recognized standard protocols. Nanotechnology- based medical devices and drug carriers are emerging as alternatives to conventional small-molecule drugs, and in vitro evaluation of their biocompatibility with blood components is a necessary part of early preclinical development. Many research papers have reported nanoparticle hemolytic properties but, so far, no in vitro hemolysis protocol has been available that is specific to nanoparticles. A new study published this month describes in vitro assays to study nanoparticle hemolytic properties, identifies nanoparticle interferences with these in vitro tests and provides the first comprehensive insight to potential sources of this interference, demonstrates the usefulness of including nanoparticle-only controls, and illustrates the importance of physicochemical characterization of nanoparticle formulations and visually monitoring test samples to avoid false-positive or false-negative results.
Having come a long way from pottery and tableware, modern advanced ceramics are high-performance materials that find use in things such as bio-medical implants, jet engine turbine blades, superconductors, missile nose cones, scratch-proof watches, or the heat protection tiles used on the Space Shuttle. Super-tough and ultra-high temperature resistant materials are in critical need for applications under extreme conditions such as jet engines, power turbines, catalytic heat exchangers, military armors, aircrafts, and spacecrafts. Structural ceramics have largely failed to fulfill their promise of revolutionizing engines with strong materials that withstand very high temperature. The major problem with the use of ceramics as structural materials is their brittleness. Although many attempts have been made to increase their toughness, including incorporation of fibers and particles, currently available ceramics and their composites are still not as tough as metals and polymers. The brittleness of ceramic materials has not yet been overcome and it has proven difficult to solve this problem by conventional material engineering approaches. The extraordinary mechanical properties of carbon nanotubes (CNTs) have generated strong research interest in their possible use in reinforced composite materials because incorporating CNTs into a ceramic matrix might be expected to produce tough as well as highly stiff and thermostable ceramic composites.
The use of spontaneous self-assembly as a lithography- and external field-free means to construct well-ordered, often intriguing structures has received much attention for its ease of organizing materials on the nanoscale into ordered structures and producing complex, large-scale structures with small feature sizes. These self-organized structures promise new opportunities for developing miniaturized optical, electronic, optoelectronic, and magnetic devices. An extremely simple route to intriguing structures is the evaporation-induced self-assembly of polymers and nanoparticles from a droplet on a solid substrate. However, flow instabilities within the evaporating droplet often result in non-equilibrium and irregular dissipative structures, e.g., randomly organized convection patterns, stochastically distributed multi-rings, etc. Therefore, fully utilizing evaporation as a simple tool for creating well-ordered structures with numerous technological applications requires precise control over several factors, including evaporative flux, solution concentration, and the interfacial interaction between solute and substrate.
The electrical properties of graphene have been the topic of recent interest from various disciplines because this novel carbon material offers exciting opportunities to develop nanocomposites with unusual electronic catalytic properties. Most of these studies involve mechanical peeling of individual graphene sheets - one at a time - from a block of graphite. The requirement to obtain graphene as individual sheets and to maintain it in the reduced form introduces a certain level of complexity into the process of designing composite systems where, for instance, semiconductor or metal nanoparticle are anchored on graphene sheets. Without some form of intervention, the strong van der Waals interactions between reduced graphene sheets would cause them to collapse and aggregate. Researchers have now developed a simple photocatalytic method to anchor semiconductor nanoparticles on a single sheet of graphene using a solution-based process.