Three-dimensional paper-based electrochemiluminescence device for simultaneous detection of Pb2+ and Hg2+ based on potential-control technique.

In this work, a microfluidic paper-based analytical device (μPADs) has been proposed for simultaneous electrochemiluminescence (ECL) detection of lead ion (Pb(2+)) and mercury ion (Hg(2+)) based on oligonucleotide. The functionalized wax-patterned three-dimensional (3D) paper-based ECL device that can provide fast, cost-effective, simple, and sensitive detection for analysis was dependent on Pb(2+) and Hg(2+)-induced conformational change of DNA strands through the formation of G-quadruplex and T-Hg-T complex, respectively. The carbon nanocrystals (CNCs) capped silica nanoparticles (Si@CNCs) and Ru(bpy)(3)(2+)-gold nanoparticles (AuNPs) aggregates (Ru@AuNPs) were both used as ECL labels in our case. Structure characterization of Si@CNCs and Ru@AuNPs were obtained by the transmission electron microscope (TEM). Due to the different operational potentials of Si@CNCs and Ru@AuNPs, Pb(2+) and Hg(2+) coexisting in one paper working zone can be determined simultaneously with detection limits of 10 pM and 0.2 nM, respectively. Finally, this simple and cost-effective device was successfully applied for simultaneous detection of Pb(2+) and Hg(2+) in lake water and human serum samples, respectively.