Ag-enhanced MOF-based electrochemical biosensor for sensitive detection of uracil-DNA glycosylase activity in cellular systems

The detection of UDG activity is essential for understanding DNA damage repair mechanisms, assessing cellular genetic stability, and advancing diagnostics and treatments for related diseases. An advanced electrochemical biosensor based on a silver-enhanced copper metal–organic framework (Ag@Cu-MOF) has been developed for the sensitive and selective detection of uracil-DNA glycosylase (UDG) activity in cellular environments. This design incorporates a prism substrate to stabilize the liquid phase on the electrode surface, with DNA probes immobilized on the prism surface. Upon UDG-catalyzed uracil excision, the probe undergoes structural changes, initiating a cascade reaction. The abundance of free DNA ends facilitates the approach of MOF materials to the electrode interface, creating a stable environment conducive to H 2 O 2 reduction, thereby amplifying the electrochemical signal. Comparative catalytic analyses revealed that the Ag@Cu-MOF-modified electrode, with its enhanced conductivity and high surface area, achieved efficient catalysis compared to Cu-MOF. The biosensor exhibited a linear response to UDG concentrations ranging from 0.00002 to 0.5 U/mL, with an impressively low detection limit of 0.00002 U/mL, highlighting its capability for quantitative analysis. The sensor demonstrated high selectivity, minimal interference from other biomolecules, and stable performance across multiple cycles, underscoring its robustness. Furthermore, UDG activity was successfully detected at varying cell densities and under hypoxic conditions, providing valuable insights into cellular DNA repair mechanisms and responses to stress. In summary, the Ag@Cu-MOF-based biosensor offers a promising platform for detecting UDG activity in cancer diagnostics and cellular research, with potential applications in monitoring DNA repair activities under both physiological and pathological conditions.