A modular self-assembled sensing system for heavy metal ions with tunable sensitivity and selectivity

Here we describe a self-assembled sensing system composed of three separate modules: gold nano particles, a reporter element, and a recognition element. The gold nanoparticles serve as a multivalent platform for the interaction with both the reporter and recognition element and the gold nucleus serves to affect the fluorescent properties of the reporter. The reporter element serves for generation of the output signal. The recognition element serves to make the assay selective. The working principle is that the interaction of the analyte with the recognition element leads to an increased affinity for the gold nanoparticle, which causes a displacement of the reporter and a turn-ON of fluorescence. It is shown that the modular nature of the system permits straightforward tuning of the dynamic detection range, the sensitivity, and the selectivity, simply by changing the recognition module. The system can detect Hg2+ and Ag+ metal ions at nanomolar concentrations in aqueous buffer.