Uses of Nanoparticles/Nanomaterials
This section is not remotely inclusive, but gives you a few examples of nano-based products that are currently available, and others that are in development.
A. Consumer Products
Several commercially available products already use nanoparticles for their desirable properties. 3M makes a dental composite called Filtek™ that consists of nanosilica particles. Other companies use nanofibers to impart stain and wrinkle resistance to fabrics. Tennis balls manufactured with nanoclay particle cores hold air pressure longer than conventional balls. Zinc oxide nanoparticles are now common in many sunscreens and cosmetics, the advantage being that the nanoparticles are transparent (unlike the larger particles) so the products are clear rather than white. Of course, nanotechnology also has a rich present and future in computing and technological applications, to create smaller and more powerful chips. In the coming years, the number of these nano-based consumer products is expected to grow exponentially.
B. Laboratory Products
Many nanotech-based products are already used in research laboratories, and you might already have some of these in your lab. New scintillation fluids contain proprietary fluor-containing nanoparticles that do not require organic solvents as the carrier. The advantage is that used scintillation cocktail is only radioactive waste, rather than mixed radioactive and ignitable waste, saving disposal costs. Sturdy fluorescent probes are now available, using quantum dot semiconductor particles. Recently, scientists were able to combine polyguanine with silica nanoparticles to create a new electrochemical immunosensor for TNF-α1.
C. Uses in Medicine
The ability to employ nanoparticles and create nanomaterials holds great potential in the field of medicine, as many diseases result from damage at the molecular or cellular level. Therefore, the ability to deliver pharmaceuticals and therapeutic gene “payloads” at the cellular level, with nanomaterials acting as the delivery system, holds great promise. For example, calcium phosphate nanoparticles can deliver DNA to particular cells targeted for gene therapy2. A recent breakthrough in imprint lithography allows the production of monodisperse nanoscale particles that can effectively contain delicate payloads3. In the near future, it might be possible for engineered nanomaterials to take over the function of damaged/defective subcellular organelles such as mitochondria4.
D. Carbon Nanotubes
Carbon nanotubes (CNTs) also deserve attention, since they are a basic building block for many current and future products. These allotropes of carbon assemble themselves into cylindrical sheets. Single-walled CNTs have a diameter of approximately 1.3 nm, while multi-walled CNTs have larger diameters that are still within nanoscale.
Representation of a single-walled carbon nanotube.
CNTs can be up to several millimeters long, and possess tensile strength more than twenty times greater than carbon steel. CNTs also are efficient conductors of heat, excellent electron emitters, and can assemble into strong ropes of increasing diameter through VanDerWaal’s forces. All of these are highly desirable material properties. Currently, CNTs are used in diverse applications such as lightweight carbon fiber bicycle pieces, water desalination filters, concrete strengthening, and solar cells. Their field emission properties have been harnessed to produce scanning X-ray imaging systems5. As the production and use of carbon nanotubes in laboratory research environments increases, the potential for exposure to CNTs also increases. The next section will cover known and suspected health effects from CNTs and other nanomaterials.
1Wang J, Liu G, Engelhard MH, and Lin Y. Sensitive Immunoassay of a Biomarker Tumor Necrosis Factor-a Based on Poly(guanine)-Functionalized Silica Nanoparticle Label. Analy Chem 78(19): 6974-6979 (2006).
2Roy I, Mitra S, Maitra A, and Mozumdar S. Calcium Phosphate Nanoparticles as Novel Non-Viral Vectors for Targeted Gene Delivery. Intl J of Pharmaceutics 250(1): 25-33 (2003).
3Euliss LE, DuPont JA, Gratton S, and DeSimone J. Imparting Size, Shape, and Composition Control of Materials for Nanomedicine. Chem Soc Reviews 35: 1095-1104 (2006).
4Datta R and Jaitawat SS. Nanotechnology – The New Frontier of Medicine. Med J Armed Forces India 62(3): 263-268 (2006).
5Zhang J, Yang G, Rajaram R, Guan E, Lee Y, LaLush D, Chang S, Lu JP, and Zhou O. A Stationary Scanning X-ray Imaging System based on Carbon Nanotube Field Emitters. Med Physics 33(6): 2159 (2006).