Highly sensitive and catalytic electrochemical biosensor for BPDE-DNA adduct detection based on a new polymerase inhibition strategy

Benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide-DNA (BPDE-DNA) adduct is a critical biomarker for assessing DNA damage caused by carcinogen exposure and exhibits significant potential in lung cancer early warning. However, conventional BPDE-DNA detection methods are often constrained by limited sensitivity, complexity and high costs. This work presents the fabrication of a highly sensitive electrochemical BPDE-DNA biosensor based on a new polymerase activity inhibition strategy coupled with AuNPs/MoS 2 /Ti 3 C 2 and HRP-catalyzed signal amplifications. A three-strand DNA complex is designed to capture the target BPDE-DNA adduct by means of a toehold-mediated strand displacement reaction (TSDR) on AuNPs/MoS 2 /Ti 3 C 2 -modifed electrode. The bulky structure of the BPDE moiety subsequently introduces steric hindrance to inhibit extension of BPDE-DNA by Klenow fragment (KF) polymerase to displace the biotin-modified sequence in the three-strand complex. Streptavidin-horseradish peroxidase (STV-HRP) is then attached to electrode surface via high-affinity biotin-STV binding. The anchored HRP coupled with AuNPs/MoS 2 /Ti 3 C 2 catalyzes redox reaction of the 3,3’,5,5’-tetramethylbenzidine (TMB)/H 2 O 2 substrate solution, resulting in a substantially amplified electrochemical current for detecting BPDE-DNA in range of 0.5 pM to 10   nM with low detection limit of 0.34 pM. Our sensor methodology not only introduces a new steric hindrance strategy for BPDE-DNA detection but also offers a robust electrochemical platform for monitoring other low levels of DNA adducts.