DNA-based biosensors for Hg2+ determination by polythymine-methylene blue modified electrodes

Mercury together with other heavy metals is one of the most worrisome environmental contaminant: mainly because of its metabolic inertia it remains permanently in the body procuring metabolic and structural damage to the cells for its ability to interact with proteins. Several methods have been developed for the determination of mercury in environmental samples, but the problems related to the selectivity and interference of other metals still remain. Among the various forms thereof, for mercury (II) ion Hg2+ the Environmental Protection Agency (EPA) has set the limit at 10 nM concentration in drinking water. Nevertheless, the electrochemical methods can be hardly applied due to low sensitivity. In this work we have developed a new electrochemical DNA-based biosensor for the selective determination of the Hg2+ ion by the use of different electrodes modified with polythymine, bearing Methylene Blue, as redox probe, in 3' position. The determination of Hg2+ can be employed with an excel