Ag/TiO2 nanocomposites as a novel SERS substrate for construction of sensitive biosensor

[Display omitted] •The excellent Raman enhancement property of Ag/TiO2 nanocomposites due to the SPR and CT could improve the sensitivity of the biosensor.•The target UDG could initiate the Pb2+ DNAzyme cleavage reaction, which effectively improved the sensitivity of the proposed biosensor.•A method without other enzyme assistance was proposed to fabricate a SERS biosensor for UDG detection. In this work, the Ag/TiO2 nanocomposites was fabricated by catalytic hairpin assembly (CHA) strategy to construct surface-enhanced Raman scattering (SERS) biosensor for sensitive detection of uracil DNA glycolase (UDG), which could achieve greater Raman enhancement of methylene blue by the surface plasmon resonance (SPR) of Ag nanocubes (Ag NCs) and the charge transfer (CT) effect of TiO2 compared with traditional noble metal material. Impressively, the Pb2+ assisted DNAzyme cleavage reaction was introduced to convert the trace target UDG into great number of trigger DNA for improving the sensitivity of this method. Thus, the SERS biosensor demonstrated excellent performance for sensitive detection of UDG with a low detection limit of 1.2 × 10−5 U mL-1. This proposed assay offered a new strategy to design SERS substrate for analysis of biomolecule and disease diagnosis.