The importance of bio-durability of carbon nanotubes
Bio-durability is an in vitro notion of a material’s persistence studied in detail using cells or biological fluids. The study of material bio-durability involves immersing the material in biologically relevant fluid, carefully selected to mimic the biological environment After incubation in the testing solution, the fate of the material is studied.
Recent research has shown that…
- the durability of single-walled carbon nanotubes (SWCNT) is dependent on their surface chemistry, in particular the presence of carboxylic groups favoured degradation in an acidic and pro-oxidant environment (Liu et al. 2010);
- single-walled carbon nanotubes (SWCNT) with carboxylic acid groups on their surface degraded over time when incubated in the presence of peroxidase and hydrogen peroxide (Allen et al. 2008). Peroxidase is a protein that promotes the oxidation of molecules using hydrogen peroxide, which can be found in cellular compartments specialised in the ‘digestion’ of foreign bodies such as bacteria;
- in a panel of four different single and multi-walled CNT immersed in an acidified physiological solution, only one was significantly altered over time, in terms of mass and length (Osmond-McLeod et al. 2011), suggesting that different not all CNT behave the same in terms of durability and that physico-chemical characteristics are important when considering the potential degradability of a material.
What does this mean?
Specific modification of surface chemistry, such as carboxylation, could favour degradation in vivo, and reduce the adverse effects from bio-persistence of CNT. A better understanding of the (bio)degradation of materials can inform the development and application of, for example, new medical and pharmaceutical products using a safety-by-design approach.
SAFENANO considers it advisable to include durability studies as part of an integrative hazard assessment of CNT and other nanomaterials.
Durability studies are included in our Product Safety & Toxicology services. For further information on these or any of our other services, please click here
Allen, B.L., Kichambare, P.D., Gou, P., Vlasova, I.I., Kapralov, A.A., Konduru, N., Kagan, V.E., Star, A. 2008, “Biodegradation of single-walled carbon nanotubes through enzymatic catalysis,” Nano Lett. Vol. 8, no. 11, pp. 3899-903.
Liu, X,. Hurt, R.H., Kane, A.B. 2010, “Biodurability of Single-Walled Carbon Nanotubes Depends on Surface Functionalization,” Carbon, vol. 48, no. 7, pp. 1961-1969.
Osmond-McLeod, M.J., Poland, C.A., Murphy, F., Waddington, L., Morris, H., Hawkins, S.C., Clark, S., Aitken, R., McCall, M.J., Donaldson, K. 2011, “Durability and inflammogenic impact of carbon nanotubes compared with asbestos fibres,” Part Fibre Toxicol, vol. 8, no. 15.