Amplified oxygen reduction signal at a Pt-Sn-modified TiO2 nanocomposite on an electrochemical aptasensor

Lele Li, Xiaoqiang Liu, Liwei Yang, Si Zhang, HeJie Zheng, Yunfei Tang, Danny K. Y. Wong

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    22 Citations (Scopus)


    In this work, a metallic composite with strong electrocatalytic property was designed by uniformly decorating Pt and Sn nanoparticles on the surface of TiO2 nanorods (Pt–Sn@TiO2). A detection scheme was then developed based on a dual signal amplification strategy involving the Pt–Sn@TiO2 composite and exonuclease assisted target recycling. The Pt–Sn@TiO2 composite exhibited an enhanced oxygen reduction current owing to the synergistic effect between Pt and Sn, as well as high exposure of Pt (111) crystal face. Initially, a Pt–Sn@TiO2 modified glassy carbon electrode produced an amplified electrochemical signal for the reduction of dissolved oxygen in the analyte solution. Next, a DNA with a complementary sequence to a streptomycin aptamer (cDNA) was immobilised on the Pt–Sn@TiO2 modified electrode, followed by the streptomycin aptamer that hybridised with cDNA. The corresponding oxygen reduction current was diminished by 51% attributable to the hindrance from the biomolecules. After a mixture of streptomycin and RecJf exonuclease was introduced, both the streptomycin-aptamer complex and the cDNA were cleaved from the electrode, making the Pt–Sn and Pt (111) surface available for oxygen reduction. RecJf would also release streptomycin from the streptomycin-aptamer complex, allowing it to complex again with aptamers on the electrode. This has then promoted a cyclic amplification of the oxygen reduction current by 85%, which is quantitatively related to streptomycin. Under optimal conditions, the aptasensor exhibited a linear range of 0.05–1500 nM and a limit of detection of 0.02±0.0045 nM streptomycin. The sensor was then used in the real-life sample detection of streptomycin to demonstrate its potential applications to bioanalysis.
    Original languageEnglish
    Article number111525
    Pages (from-to)1-10
    Number of pages10
    JournalBiosensors and Bioelectronics
    Publication statusPublished - 1 Oct 2019


    • Pt-Sn@TiO₂ composite
    • Oxygen reduction reaction
    • Electrochemical aptasensor
    • RecJf exonuclease
    • Streptomycin
    • Pt-Sn@TiO composite
    • RecJ exonuclease


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