The development of nanotechnology has led to a gradual improvement in the properties of nanomaterials (NMs), which are already used for a wide range of applications in electrical engineering, medicine, construction and agriculture. Therefore, it is important to know and understand the biological reactivity and potential toxicity and risks of NMs. In this MSc thesis, the biological reactivity of 12 different selected graphene oxides (GOs), classified as 2D nanomaterials, was tested. The biological reactivity of the selected GOs was determined by testing inhibition and adsorption on the isolated acetylcholinesterase (AChE) enzyme using the Ellman method adapted to microtitre plates. The two GOs that differed most in reactivity as measured by AChE activity assays were further tested by cytotoxicity assays on the A549 and Beas-2B cell lines, namely the neutral red dye uptake assay and the resazurin assay. We found that GOs are highly reactive materials, with high inhibition and adsorption rates even at very low material concentrations. The reactivity was dependent on the concentration of GO, with lower AChE activity measured at higher GO concentrations. From the data it can be concluded that much of the inhibition of the AChE is due to adsorption of GO onto the enzyme. The cytotoxicity and reactivity results of the two GOs tested in the AChE assay and cytotoxicity assays were in agreement, the more biologically reactive GO being more cytotoxic. The results of the correlation analysis showed that the reactivity of GO depends on the ratio of oxygen to carbon. Our results showed that GOs are biologically reactive materials, and that the degree of their reactivity depends on their physicochemical properties.
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