Dual-mode electrochemical-SERS detection of chloramphenicol based on dual-signal enhancement

The detection of chloramphenicol residues in food is critical to consumer health. To achieve efficient and sensitive detection, this study proposes a biosensor based on covalent organic framework@Au nano-flower (COF@Au NFs) and DNAzyme cascade amplification. Owing to their excellent biocompatibility, high electrical conductivity, and strong surface-enhanced Raman scattering (SERS) enhancement, COF@Au NFs serve as an efficient substrate for both electrochemistry (EC) and SERS detection.

The biosensor achieves sensitive dual-mode EC and SERS detection at femtomole levels. In the sensing system, chloramphenicol specifically activates a DNAzyme, triggering a cascade amplification reaction and releasing single-stranded DNA (S1), S1 subsequently induces the self-assembly of the sequence-specific DNA fragment EAD2 into a G-quadruplex bipedal structure capable of binding methylene blue (MB). This bipedal design enhances MB binding, thereby significantly improving both the EC and SERS responses. Experimental results demonstrate that the method exhibits an excellent linear response over the range of 1.0 × 10^-13 M to 0.1 × 10^-7 M, with an EC detection limit of 6.0070 × 10^-14 M and a SERS detection limit of 2.3472 × 10^-14 M.

This dual-mode detection method, with its high sensitivity and selectivity, holds promise for rapid and reliable chloramphenicol residue detection, providing robust technical support for food safety monitoring and further safeguarding consumer health.