Synthesis, characterisation and nanoecotoxicological assessment of a graphene oxide – gold nanohybrid

Akere, Taiwo Hassan ORCID: 0000-0002-6393-7189 (2023). Synthesis, characterisation and nanoecotoxicological assessment of a graphene oxide – gold nanohybrid. University of Birmingham. Ph.D.

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Abstract

Contemporary research in nanomaterials is focusing on the unique characteristics of multicomponent nanohybrids and their potential use in various applications. The synergistic properties of graphene oxide-gold nanohybrid (GO-Au) are already being used in applications such as biosensing and cancer detection. However, there is currently no standardised protocol for the synthesis of such nanohybrids. Also, an understanding of the fate and toxicity potential of a GO-Au nanohybrid has become pertinent due to their rapid use and resulting inevitable exposure to organisms and the environment. In addition, the possibility of using a metal-doped nanohybrid as chemical tracers for graphene oxide (GO) in environmental and biological systems is interesting for ecotoxicological studies.

In this research, GO and GO-Au nanohybrid were synthesised and characterised using several techniques including UV-Vis, TGA, TEM, FTIR, AFM, XPS and Raman. The production of the nanohybrid was repeated a number of times to verify reproducibility of the synthesis protocol. Dispersion stability of the nanohybrid in different environmental media as well as the influence of ageing on its quality were also investigated. A series of assays were performed to assess the toxicity of the nanohybrid on water flea (Daphnia magna) and cells [zebrafish embryonic cells (ZF4) and human cancer cells (A549)].

The study successfully generated batches of GO-Au nanohybrid that exhibited reproducible characteristics. The nanohybrid also showed good stability in different environmental media and its physicochemical characteristics did not deteriorate over a period of months. The amount of Au in each of the GO-Au nanohybrid samples was highly comparable, suggesting a potential for use as chemical label. Although the nanohybrid did not induce significant acute immobilization or mortality to neonates of daphnia, signs of stress and bioaccumulation were evident from the morphological images of the exposed organisms. Exposure of the nanohybrid induced dose and time dependent cytotoxicity, apoptosis and necrosis to both ZF4 and A549 cells.

The outcome of this research represents a crucial step forward in the development of a standard protocol for the synthesis of GO-Au nanohybrids. It also paves the way towards a better understanding of the nanotoxicity of GO-Au nanohybrid in biological and environmental systems.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):