Defect-Engineered Zn-CeO2 Nanointerfaces for Signal-On Electrochemical DNA Biosensing of Tuberculosis

Abstract Defect engineering of metal oxide nanomaterials offers a promising route for tailoring biointerfacial properties in electrochemical biosensing. Herein, a Zn-modified CeO2 (Zn−CeO2) nanointerface was developed for electrochemical DNA biosensing of tuberculosis. Structural characterization revealed results consistent with partial Zn incorporation into the fluorite CeO2 lattice, accompanied by lattice contraction and the presence of oxygen-vacancy related defects without the generation of secondary phases. The defect-rich Zn−CeO2 surface provided an effective platform for probe DNA immobilization and target recognition. Atomic force microscopy demonstrated progressive changes in surface topography following single-stranded DNA (ssDNA) immobilization and hybridization, leading to the formation of a compact double-stranded DNA (dsDNA) layer. Electrochemical characterization using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in the presence of methylene blue (MB) revealed a hybridization-induced signal-on response. The enhanced electrochemical response is consistent with the combined effects of oxygen-vacancy-related electronic modulation and DNA-MB interactions at the biointerface following target recognition. Under optimized conditions, the biosensor exhibited a sensitivity of 1.94 μA pM−1, a detection limit of 6.32 pM, and a linear detection range of 0.35−49 pM. The platform demonstrated excellent sequence selectivity toward complementary target DNA and successfully discriminated clinical genomic DNA samples. These findings demonstrate that Zn−CeO2 is an effective electrochemical transducer and suggest that coupling defect engineering with biointerface control is a promising strategy for the development of high-performance nucleic acid biosensors.