Our World at the Nanoscale

By Alexis Wormington

What are nanoparticles?

Nanoparticles are particles with at least one dimension sized on the nanoscale, which is usually defined as 1-100 nanometers¹ (Figure 1). Put in simpler terms, nanoparticles are very small.

Figure 1. The nanoscale²

Nanoparticles are on the same scale as many biomolecules, including antibodies, proteins, and sugars. We can’t see them, but, just like bacteria, they’re all over the place!

Where do nanoparticles come from?

Nanoparticles occur naturally in the environment – common sources include volcanic ash, ocean spray, dust, and sand³. Researchers are primarily interested in nanoparticles of synthetic (man-made) origin. Synthetic nanoparticles can be unintentional by-products of many commercial processes or intentionally synthesized for a variety of technological and industrial applications⁴. The latter are commonly referred to as engineered nanoparticles or engineered nanomaterials.

How do we use nanoparticles?

There are hundreds of different types of nanoparticles, and researchers are constantly engineering new ones in order to expand and invigorate the field of nanotechnology. Nanoparticles can be produced from a variety of elements, including carbon and metals such as titanium, gold, and silver.

Nanoparticles are interesting and useful because they have unique thermal, chemical, and optical properties compared to their larger, bulk elemental counterparts. These properties lend to a variety of applications, including those in the medical, environmental, engineering, technology, and commercial industries. Nanoparticles are often used as conductors in circuits and displays in electronic devices⁵, in textiles to improve or add functionalities (such as bacterial resistance, breathability, and strength⁶), as targeted drug-delivery vehicles in many cancer therapies⁷, and in environmental remediation efforts to bind and neutralize toxins.⁸

Figure 2. The many applications of nanotechnology⁹.

In other words, nanoparticles are everywhere! For example, the active ingredient in most SPF (sun protection factor) cosmetics is zinc or titanium dioxide nanoparticles. Soon, carbon nanotubes will replace silicon as semi-conducting transistors inside of our computers and smartphones. Some make-up products even contain gold nanoparticles!

Nanoparticles sound awesome – should we be concerned about them?

In the last ten years, the presence of nano-enabled (contains nanoparticles or nanoscale materials) products on the consumer market has increased exponentially. The Project on Emerging Nanotechnologies works on documenting nano-enabled consumer products in something called a Consumer Products Inventory (CPI). As of 2014, the CPI lists 1814 nano-enabled products currently available on the consumer market, compared to just 54 products listed in 2005¹⁰. That’s an average increase of 362% every year!

A consumer market full of nano-enabled products means that nanoparticles and nanomaterials will inevitably end up in the surrounding environment – which means the water we drink and the air we breathe. The Environmental Protection Agency is currently researching the “most prevalent nanomaterials that may have human and environmental health implications”, which includes silver nanoparticles, carbon nanotubes, cerium and titanium dioxide, iron nanoparticles, and copper nanoparticles¹¹.

The health implications of exposure to nanoparticles vary depending on the type of particle and the route of exposure, but researchers have proposed that nanoparticles smaller than 10 nm can enter biological tissue¹². Silver nanoparticles, utilized commonly in the textile industry for their antibacterial properties, release silver ions which are associated with mitochondrial and oxidative damage in both vertebrates and invertebrates¹³. A famous pilot study published in Nature Nanotechnology in 2008 found that commercially available carbon nanotube fibers induced mesothelioma-like pathologies in the abdominal cavity of mice due to their structural similarity to asbestos¹⁴. Copper oxide nanoparticles, used not only as a semi-conductor but as the active spermicide in many intrauterine devices (a form of long-term birth control), are associated with multiple organ-level effects in experimental organisms¹⁵.

There are many organizations around the world that specialize in nanosafety research. These research groups focus on understanding the behavior of nanoparticles throughout the life cycle (manufacturing, product use, and disposal) in order to determine whether they pose a potential threat to humans or the environment¹¹. This can be a daunting task – because some types of nanomaterials are more harmful than others, and some exposure scenarios are more relevant than others (i.e. inhalation versus ingestion versus injection). Nanoparticles are also maddeningly difficult to detect, which makes studying them a headache! For example, detecting carbon nanotubes in biological tissues is often described as “searching for a carbon needle in a carbon haystack”, and detection methods are still being optimized. Detection methods vary for different types of nanoparticles and range from microscopic methods (such as transmission electron microscopy), to light scattering methods, to spectroscopy techniques, to x-ray based methods¹⁶. Often times, researchers will send their samples off to another lab for quantification, because they simply do not have the proper equipment at hand!

Nanoparticles, while useful and incredibly versatile, should be approached with caution. The research on them is still in the preliminary stages, and there is still much we do not know about their potential effects on human and environmental health. As the field of nanotechnology grows, it is important to remain informed and vigilant to ensure that these particles are used safely and efficiently.

Alexis Wormington is a PhD Student at the Center for Environmental Toxicology & Chemistry at the University of Florida. Her research is focused on the toxicity of nanomaterials in aquatic ecosystems.

 

References 

1. “Nanomaterials.” National Institutes of Environmental Health Sciences. National Institute of Health, n.d. Web. 11 Jan. 2017.
2. Tarafdar, J.C., Adhikari, T. (2015). Nanotechnology in Soil Science. In Ratten, R.K. et al (Eds.), Soil Science: An Introduction (pp 775-807).
3. Lohse, Sam. “Nanoparticles Are All Around Us.” Blog post. Sustainable Nano. Center for Sustainable Nanotechnology, 25 Mar. 2013. Web. 11 Jan. 2017.
4. org. “The Future Belongs to Nano.” Omni Nano – The Curriculum to Inspire the Scientists, Entrepreneurs and Engineers of Tomorrow! N.p., n.d. Web. 03 Feb. 2017.
5. Bhatia, S., Raman, A., & Lal, N. (2013). The shift from Microelectronics to Nanoelectronics: a review. Internat J Advanc Res Comp Communic Engin, 2, 11.
6. Rivero, P. J., Urrutia, A., Goicoechea, J., & Arregui, F. J. (2015). Nanomaterials for functional textiles and fibers. Nanoscale research letters, 10(1), 501.
7. Salata, O. V. (2004). Applications of nanoparticles in biology and medicine. Journal of nanobiotechnology, 2(1), 3.
8. Khin, M. M., Nair, A. S., Babu, V. J., Murugan, R., & Ramakrishna, S. (2012). A review on nanomaterials for environmental remediation. Energy & Environmental Science, 5(8), 8075-8109.
9. Buzea, C., Pacheco, I. I., & Robbie, K. (2007). Nanomaterials and nanoparticles: Sources and toxicity. Biointerphases, 2(4), MR17-MR71.
10. Vance, M. E., Kuiken, T., Vejerano, E. P., McGinnis, S. P., Hochella, M. F., Jr., Rejeski, D. and Hull, M. S. (2015). Nanotechnology in the real world: Redeveloping the nanomaterial consumer products inventory. Beilstein Journal of Nanotechnology, 6, 1769-1780.
11. “Research on Nanomaterials.” EPA. Environmental Protection Agency, 18 Oct. 2016. Web. 11 Jan. 2017.
12. Bahadar, H., Maqbool, F., Niaz, K., & Abdollahi, M. (2015). Toxicity of Nanoparticles and an Overview of Current Experimental Models. Iranian biomedical journal, 20(1), 1-11.
13. Stensberg, M. C., Wei, Q., McLamore, E. S., Porterfield, D. M., Wei, A., & Sepúlveda, M. S. (2011). Toxicological studies on silver nanoparticles: challenges and opportunities in assessment, monitoring and imaging. Nanomedicine, 6(5), 879-898.
14. Poland, C. A., Duffin, R., Kinloch, I., Maynard, A., Wallace, W. A., Seaton, A., … & Donaldson, K. (2008). Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study. Nature nanotechnology, 3(7), 423-428.
15. Bahadar, H., Maqbool, F., Niaz, K., & Abdollahi, M. (2015). Toxicity of Nanoparticles and an Overview of Current Experimental Models. Iranian biomedical journal, 20(1), 1-11.
16. López-Serrano, A., Olivas, R. M., Landaluze, J. S., & Cámara, C. (2014). Nanoparticles: a global vision. Characterization, separation, and quantification methods. Potential environmental and health impact. Analytical Methods, 6(1), 38-56.