Dual-mode DNA nano-stage biosensing platform for efficient detection of uracil-DNA glycosylase activity in cells

Abstract

Analyzing uracil-DNA glycosylase (UDG) activity is essential for understanding DNA repair mechanisms in disease progression and treatment. This study presents a dual-mode DNA nano-stage biosensing platform integrating electrochemiluminescence (ECL) and electrochemical impedance spectroscopy (EIS) for highly sensitive and specific UDG detection. A DNA-prism-modified electrode immobilizes UDG-responsive elements, forming a stable and efficient detection interface. Upon UDG cleavage, released DNA fragments initiate rapid nano-stage assembly, significantly amplifying the signal output. ECL signals are produced by embedded [Ru(phen)₃]²⁺ complexes, while EIS signals result from the reaction of 3,3′-diaminobenzidine (DAB) with H₂O₂, catalyzed by manganese tetrakis(4-N-methylpyridyl)porphyrin (MnTMPyP). The platform achieves an exceptional detection limit of 1.0 × 10⁻⁵ U/mL, effectively validating the inhibitory effects of UDG inhibitors. Furthermore, a strong correlation between UDG activity and HeLa cell number is demonstrated. Compared to a commercial UDG detection kit, the biosensor exhibits comparable sensitivity with enhanced versatility. Notably, UDG activity is significantly higher in cancerous cells than in normal cells, reflecting the increased DNA repair demand in malignancy. This capability to distinguish UDG activity among different cell types highlights its potential for cancer diagnostics, while this biosensor platform shows promise for broader applications in clinical diagnostics, cancer research, and drug discovery.