The National Nanotechnology Initiative defines nanotechnology as the manipulation of matter with at least one dimension of a size from 1 to 100 nanometers (1 nanometer is one billionth of a meter). The prefix, “nano” is from a Greek word meaning “dwarf.” The nanometer, which is the diameter of a helium atom, is the unit of measure to express dimensions on an atomic scale. It is also used to express the wavelength of electromagnetic radiation near the visible end of the light spectrum. Because the definition is based on size, the applications can include surface science, organic chemistry, molecular biology, semiconductor physics, energy storage, microfabrication, and microengineering, among others. Currently, scientists are interested in exploring the potential of nanotechnology to create new materials and devices in nanomedicine and biomaterials, nanoelectronics, energy production, and consumer products. Here, we explore some of the strides science is making in these fields.
Nanomedicine and Biomaterials
Nanomedicine encompasses the medical applications of biomaterials and biological devices. Biomaterials science deals with engineered substances that interact with biological systems for a diagnostic or therapeutic purpose.
In medical diagnoses, nanoparticles are being used with MRIs for better tumor detection. Nanosized agents have greater magnetic susceptibility than traditional MRI contrast agents. What this means is that nanosized agents can characterize tumors on the liver more reliably and quickly when doctors introduce them in a patient intravenously. Further, testing of nanoparticles coated with antibodies, collagen, and micro-molecules is underway to determine their effectiveness for early detection of many diseases, including cancer of the breast, prostate, cervix and lung. In yet another imaging application, scientists have developed quantum dots with florescence that aid doctors in imaging and diagnosing conditions in the intestines.
The other aspect of nanomedicine is therapeutic. The current focus is on the targeted delivery of drugs, nucleic acids, and other nanoparticles to patients. Nanodevices such as the dendrometer, ceramic nanoparticles, and carbon nanotubes are useful in targeting cancer cells and cells of the immune system to treat infectious diseases like HIV and leishmaniasis. Nanodevices also help prevent rejection of transplanted organs because of a property known as immunoisolation. Perforations on the surface of nanoparticles allow the introduction of small molecules like oxygen, glucose and insulin, while impeding others like immunoglobulin. This property shows great promise in the treatment of diabetes. In the future, researchers are envisioning microbivores that could function as artificial phagocytes to destroy pathogens. Potentially, microbivores could be 1000 times more effective in clearing bacteria than phagocytes and antibiotics but without harmful side effects.
A team at Wuhan University of Technology and the Beijing Institute of Pharmacology and Toxicology in China have determined that nanoclusters of gold particles prevent the build-up of alpha-Synuclein in mice, which reversed some symptoms of neurological damage. Future successful tests in humans could lead to developing a drug that slows, or even halts, the progression of Parkinson’s, Alzheimer’s, and Lewy Body Syndrome.
Research in the area of polysynthetic fibers for faster and more effective wound closure suggests that traditional sutures may become a thing of the past. Though the materials used in sutures have improved over time, scar tissue from the healing process remains an issue and often causes reduced functionality of the affected tissue. Scientists now are developing a photosynthetic suture made of genetically modified microalgae that stimulates the production of growth factors and oxygen. Early results indicate that these microalgae could prevent scar tissue from forming and accelerate the healing process.
In one of the most interesting fields of research, doctors are teaming with engineers to advance tendon tissue engineering. The impetus for this research is the unsatisfactory outcomes yielded by current clinical treatments for tendon injuries. The possibility of an engineered strategy to regenerate tendons comes from an intriguing proposal by Professor Jan de Boer at the University of Maastricht in the Netherlands. Due to the mechanosensitive nature of tendon cells, replicating tendon cells in vitro requires mechanical stimuli for adequate cell functioning. De Boer posits that micro-typographical architectures could be the mechanical stimuli that produces biomechanical cues to control the behavior of tenocyte cells in the replication of tendon tissue.
Nanoelectronics refers to the use of nanotechnology in electronic components. Nanoelectronic devices and materials are so small as to require study of interatomic interactions and quantum mechanical properties. Experts consider nanoelectronics to be a disruptive technology in that present applications differ significantly from traditional transistors. Applications under development include clothing that can recharge electronics, vibrant paint that changes display and color, flexible computers, implantable electronic sensors for biological and health applications, and more precise sensors of gases, light, and acoustics, among others.
The current generation of wearable electronics involves fixing devices to fabrics, which can be rigid and frequently malfunctioning. The next generation of wearable or “smart” electronics will be embedded into the fabric thanks to the development of graphene. Graphene is an atomic-scale, hexagonal lattice of carbon atoms that has many unique properties. It is nearly transparent and is the strongest material ever tested. It conducts heat and electricity efficiently, and can be levitated by magnets. Engineers at the University of Exeter have devised a method for producing fully electronic fibers that can be integrated into the production of day-to-day clothing with graphene. This method has the potential to revolutionize the fashion industry with implantable sensors, biological and health applications, and more.
Nano paints contain crystalline particles. A low-grade magnetic field controls the ability of the particles to reflect light and change color. This application is already in use for cars, buildings (interiors and exteriors), and a variety of consumer and industrial products. A small electromagnetic charge maintains the color, and at the press of a button the colors can change.
Flexible Computers and Sensors
Nanoelectronics are also transforming computers and their uses. For example, a biomaterials scientist at MIT is testing a tiny pill that is an ingestible computer. The pill combines a microphone, thermometer, and a battery to collect data from inside the body. Other ingestible computers include the Proteus sensor that tracks how patients take prescribed medications, and a PillCam that allows people to skip colonoscopies.
There are a variety of ways experts are exploring more efficient and cost-effective energy production. Researchers are demonstrating that concentrated sunlight on nanoparticles produces steam with high energy efficiency (more than twice the efficiency of fluorescence bulbs, in fact). The intended use is for developing countries to run power plants and purify water.
A non-engineered polymer is being used in high-efficiency light bulbs. The polymer makes these bulbs shatterproof. Others are seeking to use nano-sized crystalline structures wrapped around the filaments in incandescent bulbs to convert some of the infrared radiation to visible light.
Light-weight windmill blades made of carbon nanotubes can potentially produce more electricity. Sheets of nanotubes wrapped around heat sources (e.g., the exhaust pipe of a car) generate electricity from what currently is “wasted” heat. Piezoelectric nanofibers woven into clothing turn normal motion into electricity, powering cell phones and other mobile devices. New nanotechnology in batteries charges them faster and extends their shelf-life life for decades. Other applications are in development for Solar Cells, Fuel Cells, and Fuels themselves.
Some of the more interesting consumer products with nanotechnology include:
- A topical nanoparticle application that is more effective in blocking UV rays without leaving a residue on the skin
- Lithium batteries with nanoparticle-based electrodes for electric cars
- Flame-retardant coatings for microfibers in furniture
- Titanium oxide nanoparticles in film that uses energy from light to kill bacteria on surfaces
- Silica nanoparticles to fill spaces between carbon fibers to strengthen a variety of sporting good products
- Nanoporous material, called aerogel, insulates walls of buildings and is 66% thinner than traditional insulation
In 1959, Richard Feynman delivered a lecture to the American Physical Society entitled, “There’s Plenty of Room at the Bottom.” In his talk, he argued that humans would continue to innovate smaller and more powerful devices. How right he was! In 1986, K. Eric Drexler first introduced the term, “nanotechnology.” Clearly, advancements in nanotechnology are showing us that more and more science fiction is becoming science fact.