A selective sensor for cyanide ion (CN−) based on the inner filter effect of metal nanoparticles with photoluminescent carbon dots as the fluorophore

Herein, we report a plasmonic metal nanoparticle-involved sensor for cyanide ion based on the inner filter effect by using photoluminescent carbon dots as the signal reporter. With commercial bee pollen as the carbon resource, we synthesized photoluminescent nitrogen-doped carbon dots by a one-pot hydrothermal process, and their fluorescence quantum yield reached as high as 10.2% ± 0.5%. Fluorescence measurements indicated that the fluorescence of the carbon dots was insusceptible to the presence of many environmentally ordinary ions. Thanks to this “inert” property, we then developed a turn-on fluorescent sensor for cyanide ion in an inner filter effect manner by using carbon dots as the fluorophore and gold or silver nanoparticle as the light absorber. This detection technique is expected to be used for other metal nanoparticles-carbon dots ensemble fluorescent assays.