DNAzyme amplified dispersion state change of gold nanoparticles and its dual optical channels for ultrasensitive and facile detection of lead ion in preserved eggs

A dual-mode sensing platform for Pb 2+ was constructed based on the dual optical channels of Au NPs system with the amplification of DNAzyme, and it was successfully applied for Pb 2+ determination in preserved egg with satisfactory results. The presence of Pb 2+ activated the DNAzyme and induced the dispersion change of Au NPs in high salt concentration. The sequent absorption change of Au NPs was translated to the fluorescence change of carbon dots through FRET, and the scattering change was transferred to grey value of images involving the Tyndall effect. Thus, a sensing platform based on fluorescence and colorimetric dual-technique was achieved for Pb 2+ detection, under the optimized conditions. With the assistance of DNAzyme, the linear range of fluorometric and colorimetric method were 2.0 × 10 -14  ∼ 8.0 × 10 -10 mol/L and 2.4 × 10 -13  ∼ 9.5 × 10 -9 mol/L, respectively. The dual-mode sensing platform demonstrated its promising application in the environmental monitoring and food safety field.