DNAzyme amplifaction strategy coupled with peanut-shaped FexOy@MMC@Au and COF@Au synergistic SERS enhancement for ultrasensitive analysis of chloramphenicol

In this study, a target induced DNAzyme amplifaction strategy was developed combining with peanut-shaped FexOy@macro-/mesoporous carbon (MMC)@Au and covalent organic frameworks (COF)@Au to construct surface enhanced Raman spectrum (SERS) aptasensor for ultrasensitive detection of chloramphenicol (CAP). The polydopamine was firstly self-polymerized on the peanut-shaped Fe2O3 as a reductant to generate a uniform assembly of AuNPs, with multiple hotspots, to achieve high reproducibility. After carbonation process, the obtained magnetic peanut-shaped FexOy@MMC@Au could effectively avoid the Raman interference of the SERS substrate. When target CAP was dropped into the aptamer and DNAzyme double chains, CAP could specifically combining with aptamer, releasing DNAzyme chain to cut off hairpin DNA which was already assembled on the FexOy@MMC@Au. At this time, COF@Au@toluidine blue (TB)@S1 can be attract closed to the SERS substrate due to the complementation of S1 with residual hairpin DNA to produce strong Raman signal. Based on this principle, the SERS aptasensor for the detection of CAP possessed a very low limit of detection (LOD) of 7.35 fM was obtained. The results suggested the potential of this SERS aptasensor for sensitive and selective CAP diagnosis and be applied to the clinical and biochemical analysis.