GrapheneBiosensor · Electrochemical Graphene Sensors as Early Alert Tools for Algal Toxin Detection in Water

Electrochemical Graphene Sensors as Early Alert Tools for Algal Toxin Detection in Water

Episodes of harmful algal blooms (HAB) of cyanobacteria, known as blue-green algae, occur frequently in bodies of water worldwide as a consequence of eutrophication resulting from anthropogenic activities such as agricultural run-off, urban waste, and manufacturing of detergents and global warming. Cyanobacterial HAB often produce undesirable color, odor, and tastes but most importantly, it also produces harmful toxins (i.e. cyanotoxins), which is a significant hazard for human health and the ecosystem in drinking water, recreational water, and aquaculture. The coastlines of many European countries (including UK) are frequented by large scale of HAB events. Following a significant HAB event, there is an urgent need to establish when a water source is safe to use or to evaluate the level of treatment required to make a source safe. Among cyanotoxins, microcystin-LR (MC-LR) is the most frequently occurring variant throughout the world. It had been confirmed that microcystins were responsible for some poisonings of animals and humans where water sources contained toxic cyanobacteria blooms. Acute or prolonged exposure to microcystins would cause liver damage, followed by a massive intrahepatic haemorrhage and probably leading to death. In 1998, the provisional guideline concentration limit of 1 μg/L MC-LR in drinking water was assigned by the World Health Organization (WHO). The development of reliable methods for monitoring MC-LR in water resources is of great interest to determine the occurrence and to prevent exposure to the toxin. Several methods have been developed to detect MC-LR, such as high-performance liquid chromatography/mass spectrometry (HPLC/MS), which require long processing times, sophisticated instruments, complex procedures, or high processing cost and are in general used in the laboratory, not in situ. In the last decade, electrochemical sensors have become a mature discipline with some outstanding commercial success. They are suitable devices for in situ monitoring, due to their possible miniaturisation, portability and automation. A sensitive, specific, simple, and rapid method for monitoring MC-LR could help to prevent exposure to the toxin. The overall aim of this project is to design, fabricate and validate electrochemical sensors based on flexographic-printed vertically aligned graphene (VAG) electrodes for the rapid, sensitive and reliable detection of MC-LR in water. This was realized by achieving the following main project objectives: 1. VAG electrode fabrication under controlled laboratory conditions 2. VAG biosensor platforms optimisation for sensitive and selective sensing design 3. Optimisation of graphene based biosensing platforms for MC-LR detection in laboratory 4. Performance validation of developed VAG biosensor in drinking water sources

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