Portable Microalgal Biosensor for Herbicide Monitoring

Abstract

The need for in-situ and real-time tools to monitor the fate ofpesticides in extensive areas is of great concern to preserve theenvironment in countries where agroindustry represents anessential part of its economy. In this work, we present theconstruction of a portable system based on the reversiblephotosynthesis inhibition produced by herbicides on micro-algae, using atrazine as a model compound. The decrease inoxygen production due to the photosynthesis inhibition iselectrochemically detected using an automated flow system.The system presented here involves the immobilization of microalgae in a polyelectrolyte-surfactant-carbon nanotubeself-assembled material cast on a screen-printed graphiteelectrode; these components contribute to the stability andsensitivity of the whole device. The system presents a limit ofdetection of 0.11 μM, showing an excellent performance in riversamples. The sensor maintains its integrity after five monthsimmersed in a freshwater algae medium at room temperature.These features are key to install this system along the course ofa river at a low cost, allowing early detection of polluted areasand long term environmental studies.