Investigation for Regulation of a DNA-Programmed Bimetallic Nanozyme and Its Biosensing Applications

The DNA-mediated growth strategy of bimetallic nanozymes is considered as an effective approach to regulate their peroxidase activity via tuning the morphology and nanostructure. Albeit important, its biosensing application in rational methods' design and performance improvement is limited due to the deficiency of a systematic understanding of the interactions between DNA and nanomaterials used. Herein, four homo-oligonucleotides as capping ligands were employed to functionalize the bimetallic nanozymes, where Pt nanoparticles (PtNPs) were in situ synthesized onto DNA-bound Au nanorods (AuNRs), and the effects of DNA with different lengths on the state of bimetallic nanozymes were investigated in detail. It was found that the aggregation of AuNRs obviously depended on the variety and number of DNA oligonucleotides with the absorbance ratio at 810 and 525 nm (A810/A525), ranking as follows: AuNRs/A10/PtNPs > AuNRs/G10/PtNPs > AuNRs/C10/PtNPs ≫ AuNRs/T10/PtNPs, which is consistent with the value of Km for TMB, indicating that the dispersal/aggregation of the AuNRs is closely related to the deposition and growth of PtNPs, thereby significantly influencing their peroxidase activity. According to our discoveries, a novel colorimetric array platform was fabricated using the above four types of DNA-encoded Pt–Au bimetallic nanozymes as sensing elements for sensitively discriminating the five biological thiols (l-cys, GSH, Hcy, DTT, and Cys–Gly) and identifying the normal cells/tumor cells, respectively. Our work provides a new insight into DNA-programmed bimetallic nanozyme regulation and broadens its sensing applications.