Sensitive detection of FPG based on 8-oxoG modified chimeric peptide-DNA enzyme for oxidative damage evaluation.

Formamidopyrimidine DNA glycosylase (FPG) is a crucial DNA repair enzyme that specifically recognizes and excises the damaged base 7,8-dihydro-8-oxoguanine (8-oxoG). The current detection technology for FPG is limited due to the need of integrating the relatively independent identification components and signal amplifiers. Herein, we designed an integrated probe (loaded on magnetic beads), which contained 8-oxoG for FPG recognition and a novel chimeric peptide-DNA mimetic enzyme (CPDzyme) for chemiluminescence (CL) signal amplification. Once the FPG recognized the probe, the CPDzyme was excised from the surface of the magnetic beads. Therefore, the change in CL signal caused by CPDzyme on the surface of the magnetic spheres before and after recognition and cleaning could be quantitatively analyzed for FPG. Thanks to the powerful catalytic ability of CPDzyme and the simplicity of the CL system, this method could detect the activity of FPG in a linear range of 0.2-20 U/mL, with the detection limit as low as 0.06 U/mL. Further, we applied the strategy to the detection of FPG activity in human serum and bacterial samples (before and after UV irradiation), demonstrating its potential for the monitoring of oxidative damage. With excellent sensitivity and standardized operation, this strategy demonstrates superior characteristics to commercial assay kits and is expected to provide a new powerful tool for relevant research.