An ionic liquid supported CeO(2) nanoparticles–carbon nanotubes composite-enhanced electrochemical DNA-based sensor for the detection of Pb(2+)

An electrochemical sensor incorporating a signal enhancement for the determination of lead (II) ions (Pb(2+)) was designed on the basis of the thrombin-binding aptamer (TBA) as a molecular recognition element and ionic liquid supported cerium oxide (CeO(2)) nanoparticles–carbon nanotubes composite modification. The composite comprises nanoparticles CeO(2), multi-wall carbon nanotubes (MWNTs) and hydrophobic room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF(4)). The electrochemical sensors were fabricated by immersing the CeO(2)–MWNTs–EMIMBF(4) modified glassy carbon electrode (GCE) into the solution of TBA probe. In the presence of Pb(2+), the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb(2+) and TBA. The TBA-bound Pb(2+) can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb(2+). The reduction peak current is linearly related to the concentration of Pb(2+) from 1.0×10(–8) M to 1.0×10(–5) M with a detection limit of 5×10(–9) M. This work demonstrates that the CeO(2)–MWNTs–EMIMBF(4) nanocomposite modified GCE provides a promising platform for immobilizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.