An ionic liquid supported CeO nanoparticles-carbon nanotubes composite-enhanced electrochemical DNA-based sensor for the detection of Pb.

An electrochemical sensor incorporating a signal enhancement for the determination of lead (II) ions (Pb) was designed on the basis of the thrombin-binding aptamer (TBA) as a molecular recognition element and ionic liquid supported cerium oxide (CeO) nanoparticles-carbon nanotubes composite modification. The composite comprises nanoparticles CeO, multi-wall carbon nanotubes (MWNTs) and hydrophobic room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF). The electrochemical sensors were fabricated by immersing the CeO-MWNTs-EMIMBF modified glassy carbon electrode (GCE) into the solution of TBA probe. In the presence of Pb, the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb and TBA. The TBA-bound Pb can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb. The reduction peak current is linearly related to the concentration of Pb from 1.0×10 M to 1.0×10 M with a detection limit of 5×10 M. This work demonstrates that the CeO-MWNTs-EMIMBF nanocomposite modified GCE provides a promising platform for immobilizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.