Bioluminescent enzyme inhibition-based assay to predict the potential toxicity of carbon nanomaterials.

A bioluminescent enzyme inhibition-based assay was applied to predict the potential toxicity of carbon nanomaterials (CNM) presented by single- and multi-walled nanotubes (SWCNT and MWCNT) and aqueous solutions of hydrated fullerene С60 (C60 HyFn). This assay specifically detects the influence of substances on parameters of the soluble or immobilised coupled enzyme system of luminescent bacteria: NAD(P)Н:FMN-oxidoreductase+luciferase (Red+Luc). A protocol based on the optical properties of CNM for correcting the results of the bioluminescent assay was also developed. It was shown that the inhibitory activity of CNM on Red+Luc decreased in the following order: MWCNT>SWCNT>C60 HyFn. The soluble enzyme system Red+Luc had high sensitivity to MWCNT and SWCNT, with values of the inhibition parameter IC50 equal to 0.012 and 0.16mg/L, respectively. The immobilised enzyme system was more vulnerable to C60 HyFn than its soluble form, with an IC50 equal to 1.4mg/L. Due to its technical simplicity, rapid response time and high sensitivity, this bioluminescent method has the potential to be developed as a general enzyme inhibition-based assay for a wide variety of nanomaterials.