A recyclable and degradable SERS biosensor based on pH-responsive cellulose hydrogel integrated with stimulus-responsive DNA/COF for the detection of lomefloxacin

Lomefloxacin (LOM) residues in food can induce bacterial resistance and pose serious health risks. Therefore, sensitive detection of trace LOM is of great significance. A recyclable and degradable surface-enhanced Raman scattering (SERS) biosensor, which is based on stimuli-responsive DNA/covalent organic frameworks (COF) and cellulose hydrogel (CA-β-CD), was developed for the ultrasensitive detection of LOM. Specifically, by utilizing the high adsorption capacity of COF, a large number of Raman-active signal molecules (methylene blue, MB) were incorporated to form a stimuli-responsive DNA/COF complex that responds to the LOM. Subsequently, a recyclable SERS substrate was fabricated through the integration of cyclodextrin-functionalized cellulose gel (CA-β-CD) with green leaf@Ag NPs. Upon exposure to the target, LOM competitively bound to the aptamer, triggering the release of MB, which was then captured through host-guest interactions by the CA-β-CD, thereby generating a strong SERS signal. The immobilized MB can be desorbed by modulating the pH, which enables the efficient regeneration and reuse of the SERS substrate. Furthermore, the cellulose gel can be degraded in the presence of cellulase, ensuring an environmentally sustainable detection approach. The proposed method achieved ultrasensitive detection of LOM over a linear range of 1.0 × 10 −11 to 1.0 × 10 −5 mol/L, with a detection limit as low as 3.56 × 10 −12 mol/L. Moreover, the biosensor demonstrated outstanding specificity and robustness in the face of potential interferents and has been successfully applied to the analysis of real-world samples. This work offers a novel and reliable strategy for the sensitive detection of antibiotics in food matrices.