Peroxidase-mimicking nanomaterials for the detection of mercury (II) ions in water matrices
The demand for safe, sustainable and nutritious food is under immense pressure due to population growth, climate change and water deprivation. Mercury (Hg) is one of the most toxic elements on Earth, and continues to cause major threats to aquatic life, human health and the environment. Toxic methylmercury (MeHg) arises from atmospheric deposition and forms through bacterial conversion within water bodies. This highly toxic form can bioaccumulate throughout the food chain causing adverse health effects when ingested, even at low concentrations. Therefore, it is an extremely important global issue to monitor and regulate oceanic levels, to prevent the consumption of contaminated seafood and protect human health. The conventional techniques applied to detect Hg(II) ions in water samples commonly include AAS, ICP-MS, XRF, and HPLC however, these methods require lengthy procedures and expensive, bulky equipment. Therefore, there is a need to develop novel analytical techniques which are rapid, low-cost, and sensitive with the potential to be applied to the on-site analysis of water samples. Nanotechnology and colorimetric-based systems which utilise the plasmonic and catalytic properties of AuNPs have attracted much attention in recent years, due to benefits such as ease of operation, low-cost and naked-eye detection. However, nanomaterials suffer from poor stability in high electrolyte conditions therefore, most applications focus on low electrolyte water samples. This thesis focuses on the exploration and development of SPR and SERS-based colorimetric assays, which utilise the peroxidase-mimicking activity of gold (Au) nanomaterials. A main focus is also to improve applications beyond drinking and environmental water samples, by improving the stability of nanomaterials in high electrolyte conditions (i.e. seawater). Overall, this work can contribute to the protection of water systems, aquatic life and human health from toxic Hg(II) contamination, with the potential for further developments to complex matrices (e.g. seafood) and applications to on-site analysis.
gold nanomaterials, peroxidase-mimicking, nanozyme, mercury detection, water matrices
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