A microfluidic chip integrating fluorescence sensor array and electrochemical aptasensor for sensitive quantification of multiple heavy metals.

In response to the coexistence of multiple heavy metals and their complex interactions, this study developed an integrated microfluidic chip that combined a fluorescence sensor array with an electrochemical aptasensor. Various metal nanoclusters stabilized by different ligands were synthesized as fluorescence signal probes with six distinguishable emission wavelengths to form the fluorescence sensor array. Six heavy metal ions (Pb2+, Cd2+, Hg2+, As3+, Cr6+, and Cu2+) exhibited different influence on the fluorescence intensities and achieved in a variant data matrix for linear discriminant analysis. The quantification of specific heavy metal ions was realized thorough the electrochemical aptasensor, which was constructed using nucleases exonuclease-assisted and nucleic acid amplification technique. The rapid and sensitive detection of Pb2+, Cd2+, and Hg2+ was achieved with detection limits as low as 3.327 pg/mL, 7.975 pg/mL, and 1.228 pg/mL, respectively. The above two sensing strategies were successfully assembled into the microfluidic chip, in which the fluorescence sensor array realized the preliminary identification of various heavy metal ions while the electrochemical aptasensor provided a quantitative signal to improve sensitivity. This integrated microfluidic chip could successfully detect Pb2+, Cd2+, and Hg2+ in the tea sample. Therefore, the integrated device designed in this study exhibited excellent potential in the screening and quantification of multiple heavy metal ions in complex matrices.