Sequence-defined oligomer as a modular platform for selective sub-picomolar detection and removal of Hg²⁺

A modular synthetic platform for selective sensing and removal of Hg2+ was developed. This modular system possesses a unique feature to gradually increase the sensitivity even in competitive environments via increasing the number of Hg2+-coordinating units. This was made possible by synthesising a sequence-defined oligomer (SDO) with dithiocarbamate (DTC) as the Hg2+-coordinating unit in its backbone. Because it is a SDO, the Hg2+-coordinating unit was systematically increased to achieve a detection limit of 3 x 10(-13) M, which is, to the best of our knowledge, the lowest reported. Any fluorophore can be synthetically attached via post-synthetic modification of the SDO to improve the efficiency of the sensor. Additionally, any functional group can be incorporated via custom synthesis of monomer to modulate the chemical property of the sensor. The same platform was shown as a removal system for Hg2+ with >95% removal efficiency via complexation and precipitation methods.