Fig. 1. Schematic of the loading of oligonucleotides and the construction and testing process of UO₂²⁺ sensor (color online)

Fig. 2. AFM images of AM (a) and P1/AM (b), and the UV absorption spectra (c) of P1 solution with added AM (0~0.5 mg∙mL^-1) (color online)

Fig. 3. CV (a) and EIS (b) spectra of P1, AM and P1/AM (color online)

Fig. 4. UO₂²⁺ reduction peak signal changes with modification density of P1/AM (a), electrolyte pH (b), electrolyte temperature (c), and enrichment time (d) in DPV test (the insets represent the variation trends of the peak currents with error bars) (color online)

Fig. 5. Linear fitting curve of the variation of UO₂²⁺ reduction peak current with UO₂²⁺ concentration obtained by DPV tests using the P1/AM/GCE-based electrochemical sensor (a). Histograms of original UO₂²⁺ reduction peak current in the UO₂²⁺ electrolyte and interfering ion reduction peak currents after the addition of those interfering metal ions (b)