Approaching Sensitivity of Tens of Ions Using Atomically Precise Cluster-Nanofiber Composites

A new methodology has been demonstrated for ultratrace detection of Hg2+, working the limit of a few tens of metal ions. Bright, red luminescent atomically precise,gold clusters, Au@BSA (BSA, bovine serum albumin), coated on Nylon-6 nanofibers were used for these measurements. A green emitting fluorophore, (fluorescein isothiocyanate), whose luminescence is insensitive to Hg2+ was precoate the fiber. to mercury quenched the red emission completely, an eMission Of the fiber appeared which was observed under 'dark field microscopy. For the sensing experiment at the limit of sensitivity, we have used Quenching due to Hg2+ ions was fast and uniform. Adaptation of such sensors to pH paper-like test-strips would make affordable water quality sensors at ultralow concentrations a reality.