Protein-based capacitive biosensors for the detection of heavy-metal ions

Sammanfattning: Some metal ions, such as copper and zinc, are essential nutrients and catalysts in biochemical reactions. Other metal ions, e.g. cadmium and mercury, are highly toxic elements. Heavy metals detection has proven difficult with classical as well as experimental analytical methods. Novel techniques are required for the measurement of bioavailable toxic elements and for detecting small ligands binding, often weak and transient, yet vital to most cellular processes. The here-discussed biosensors were developed for the measurement of bioavailable concentration of toxic metals and to investigate the biochemical characteristics of proteins of biomedical interest. Heavy metal ions binding proteins, e.g. SmtA and S100A12, were used as bio-recognition element. Electrochemical capacitance was used to measure the protein-heavy metal ion interaction. The aim of the thesis is to review the research and the state-of-the-art of the protein-based capacitive biosensors for the detection of heavy metal ions. It covers the main aspects of the biosensor theory, research and development, including the detection principle, with particular attention to the transducer methods and gold electrodes, heavy metal ions coordinating proteins, immobilisation methods and the experimental biosensors applications.