Synergistically enhanced surface-enhanced Raman scattering aptasensor for the quantitative monitoring of enrofloxacin in environmental waters

This study developed a highly selective and sensitive surface-enhanced Raman scattering (SERS) aptasensor for detecting enrofloxacin (ENR), a persistent fluoroquinolone antibiotic posing environmental concerns. This SERS aptasensor is constructed using flexible carbon cloth (CC) as the substrate, which is oxidized and then modified with titanium dioxide (TiO 2 ), followed by loading with gold nanoparticles (AuNPs) and functionalization with ENR-specific aptamer (Apt). The flexible nature of CC enables the substrate to adapt to irregular surfaces, providing structural support for potential portable on-site detection applications. It leverages a synergistic signal enhancement effect from localized surface plasmon resonance (LSPR) of AuNPs and the likely charge-transfer contribution of TiO 2 . A partial least squares (PLS) regression model correlated full spectral profiles with ENR concentrations, enabling accurate quantification while effectively mitigating spectral complexity and matrix interference. Under optimized conditions, the aptasensor exhibits a wide linear detection range (1–10 4 nmol/L) with a low detection limit of 0.37 nmol/L. It demonstrates good selectivity against interferents, high reproducibility, with relative standard deviation (RSD) at 1.87%, and excellent stability over 14 days (RSD below 2.83%), and accurate spiked recoveries in real water samples (96.94%–109.47%). These results show the great potential of the proposed SERS aptasensor for reliable and practical monitoring of ENR in environmental applications.