development of a biosensor for heavy metal ions based on mercury-responsive transcription factor(MerR) and local plasmon enhanced excitation

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The aim of this study was to develop a protein-based heavy metal sensor for field analysis. Gene constructs consisting of mercury-responsive transcription factor(MerR) and split yellow fluorescent protein or luciferase were prepared. The resulting E-coli and the isolated proteins showed properties of mercury ion sensor, while the sensitivities were not sufficient for practical use. Plasmonic materials such as gold and silver colloids have been employed to enhance the excitation and emission efficiency. Novel protocol for effective preparation and immobilization of flower-like gold-silver hybrid colloids on a glass substrate was established and the plasmonic substrate showed remarkable fluorescence enhancement by visible light excitation. The resulting E coli or isolated protein was immobilized on the plasmonic substrate using a PDMS microfluidics system and tested for a mercury sensor.