Magnetic nanomotor-enhanced DNA cascade reaction for imaging DNA repair-related enzyme activity

The development of a spatiotemporally resolved analytical platform capable of real-time, simultaneous tracking of base excision repair (BER) pathway-associated enzymes in living cellular systems holds significant potential for elucidating their cooperative mechanisms in disease pathogenesis and acquired therapeutic resistance. However, current simultaneous enzymatic imaging is constrained by probe integration complexity, lack inherent signal amplification capacity, and diffusion-dominated kinetics compromising response time, catalytic efficiency, and sensitivity. Herein, we report a magnetic nanomotor-enhanced double confined hybridization chain reaction (MEDC-HCR) to detect the correlated activity of apurinic/apyrimidinic endonuclease 1 (APE1) and flap structure-specific endonuclease 1 (FEN1) in an AND-gated manner. The hairpin-structured of the hybridization chain reaction (HCR) integrate dual enzymatic sensing modules for APE1 and FEN1 detection. Furthermore, the magnetic nanomotors exhibit dual functionality as confined scaffolds and efficient intracellular delivery vehicles, synergistically enhancing local probe concentration to accelerate reaction kinetics, and simultaneously improving probe stability in complex biological fluids. Clinical validation demonstrating that this method distinguishes between healthy individuals and breast cancer patients confirms its potential for clinical translation. The innovative platform serves as a versatile tool for investigating DNA repair mechanisms relevant to cancer diagnosis and treatment, and simultaneously highlights the potential of self-propelled nanomotors for molecular imaging and disease diagnostics.