Coupling exonuclease III with DNA metallization for amplified detection of biothiols at picomolar concentration.

For early diagnosis of diseases, the need of ultralow detection limit is an ongoing quest. In this work, by taking the uniqueness of Exonuclease III and DNA metallization, we demonstrate a facile turn-on fluorescent method for amplified detection of biothiols at picomolar concentration. This method relies on the amplification process achieved by the recycling of biothiols retrieved target DNA from silver depositions and the specific interactions between quadruplex and NMM. This method is simple in design, economic in operation and exhibits ultralow detection limit and excellent selectivity toward thiol-containing biomolecules among amino acids found in proteins and in serum samples. More importantly, the detection and discrimination process can be seen by the naked eye with the aid of an UV transilluminator. Therefore, this new concept may offer a potential approach for practical applications as an efficient biosensor for early detection of diseases.