Mesarič T, Baweja L, Drobne D, Makovec D, Dhawan A, Sepčić K
[ pdf ] [ site ] Toxicology Letters, 2013

Carbon-based nanomaterials (NMs) are increasingly being used in various applications such as drug deliveries, radical scavenging compounds and biosensing platforms. There have been many reports about the effects of carbon-based NMs on integrated biological systems, however much less is known on interactions of these NMs with single components of living systems like proteins. It has been shown that some NMs exert toxic effects by disrupting the native conformation of proteins and enzymes. Acetylcholinesterase (AChE) is a key enzyme present in the brain, blood and nervous system; therefore it can be used as a suitable biomarker for neurotoxicity. Experimental and computational studies were performed to assess the neurotoxic potential of carbon black (CB), graphene oxide (GO) and fullerene (C₆₀). Our experimental results showed that all tested carbon-based NMs adsorb AChE, but their effects on the catalytic activity of enzyme are different. The most efficient inhibitor was CB, causing 100% adsorption and inhibition of AChE at the concentration of few μg/mL, whereas the enzyme adsorbed onto GO surface retained its activity and native conformation. Compared to GO and CB, C₆₀ was found to be an inefficient adsorbent of AChE. Moreover, the enzyme inhibition was not related to the secondary characteristics (ζ-potential or DLS values) of NMs. The distinctive adsorption pattern of tested NMs and their inhibitory potential could be related to the surface characteristics of NMs. Our studies also demonstrate the potential of GO as a substrate for immobilization of AChE.