A sensitive DNAzyme-based electrochemical sensor for Pb2+ detection with platinum nanoparticles decorated TiO2/α-Fe2O3 nanocomposite as signal labels

In this work, a sensitive DNAzyme-based electrochemical sensor had been developed for Pb 2+ detection with platinum nanoparticles decorated TiO 2 /α-Fe 2 O 3 composite as signal labels. The morphological and compositional properties of the PtNPs/TiO 2 /α-Fe 2 O 3 were examined by using transmission electron microscopy , X-ray diffraction, and X-ray photoelectron spectroscopy. The result showed that the shape of α-Fe 2 O 3 nanocrystals were the cubic, the average length ranged from 150 to 300 nm, and the PtNPs with about 3–4 nm in diameter were well dispersed on the surface of TiO 2 /α-Fe 2 O 3 . TiO 2 /α-Fe 2 O 3 were used as a “carrier” to load the PtNPs tracers as well as for Apt3 immobilization. In turn, the DNAzyme structure of Apt1 and Apt2 was immobilized on the gold electrode surface as the capture probes. Subsequently, DNAzyme modified electrodes reacted with target Pb 2+ and the Apt3/PtNPs/TiO 2 /α-Fe 2 O 3 composite were deposited on the electrode surface. The performance of the DNAzyme-based electrochemical sensor was tested by recording the electrocatalytic reduction current toward H 2 O 2 . Enhanced sensitivity was achieved by TiO 2 /α-Fe 2 O 3 nanocomposites as a nanocarrier in order to PtNPs at a high ratio. The DNAzyme-based electrochemical sensor described here exhibited excellent sensitivity and specificity for target ion. This work represented a promising potential for on-site testing Pb 2+ in real drinking water and serum sample analysis.