A novel and adjustable lamp based on competitive interaction among dsDNA-SYBR Green I (SGI), ion quencher, and analyte
was designed for bioanalysis. The Bfilament^ and switch of the lamp could be customized by employing different dsDNA and ion
quencher. The poly(AT/TA) dsDNA was successfully screened as the most effective filament of the lamp. Two common ions,
Hg2+ and Fe3+, were selected as the model switch, and the corresponding ligand molecules cysteine (Cys) and pyrophosphate
ions (PPi) were selected as the targets. When the fluorescence-quenched dsDNA/SGI–ion complex was introduced into a targetcontaining system, ions could be bound by competitive molecules and separate from the complex, thereby lighting the lamp.
However, no light was observed if the biomolecule could not snatch the metal ions from the complex. Under the optimal
conditions, sensitive and selective detection of Cys and PPi was achieved by the lamp, with practical applications in fetal bovine
serum and human urine. This ion quencher regulated lamp for fluorescent bioassays is simple in design, fast in operation, and is
more convenient than other methods. Significantly, as many molecules could form stable complexes with metal ions selectively,
this ion quencher operated lamp has potential for the detection of a wide spectrum of analytes.

• An ion quencher operated lamp for multiplexed fluorescent bioassays