Single-Cell Super-Resolution Quantification of Oxidative DNA Damage via Aptamer-Assisted DNA-PAINT

Accurately quantifying oxidative DNA damage at the single-cell level remains a major challenge due to the limitations of conventional ensemble-based assays, which obscure cell-to-cell variability and lack molecular specificity. To address this, we developed a super-resolution imaging strategy that combines an 8-oxo-dG-specific DNA aptamer with DNA-PAINT, enabling quantitative visualization of 8-oxo-dG lesions with ∼22 nm spatial resolution in individual cells. Our approach reliably detects 8-oxo-dG clusters, distinguishes oxidative damage levels across cells, and exhibits superior specificity and labeling efficiency compared to antibody-based methods. Furthermore, it enables direct evaluation of the repair efficiency of hOGG1 and its catalytic mutants at the single-cell level, overcoming the confounding effects of variable transfection efficiency. This method also serves as a platform for assessing the effects of pharmacological modulators and antioxidants on DNA repair. Looking forward, this strategy can be extended to map other small molecular targets, such as epigenetically modified DNA or RNA bases, with single-cell precision.