A novel dual-mode biosensing platform based on Au@luminol and CdSe QDs for detection of trace heavy metal ions in PM2.5.

Multi-component analysis of PM2.5, especially heavy metal ions, is very important for the study of air pollution. In this work, a novel dual-mode biosensing platform based on Au@luminol and CdSe QDs luminophores was constructed to achieve simultaneous detection of trace Mn2+ and Cd2+ in PM2.5. Interestingly, Au@luminol and CdSe QDs both had excellent fluorescence (FL) and electrochemiluminescence (ECL) performance, which provided feasibility for dual-mode detection. Based on this characteristic, this platform adopted a classical magnetic bead-assisted enzyme cleavage amplification strategy to convert trace Mn2+ and Cd2+ into a large number of Au@luminol and CdSe QDs probes, respectively, producing excellent positive and negative potential ECL signals in the presence of the only co-reactant H2O2. The above two probes were introduced into a and b regions of ITO electrode by DNA hybridization to realize the ECL-spatial-potential resolution and simultaneous detection of Mn2+ and Cd2+. In addition, the above two probes could also be directly used for FL detection of Mn2+ and Cd2+, further improving the detection accuracy. In general, this work focused on heavy metal pollution in atmospheric particulates by using a cleverly designed dual-mode biosensor, which provided a new idea for simultaneous detection of multi-component samples.