Graphene oxide–Ag decorated optical fiber SERS substrate for ultratrace molecular detection

GO/Ag SERS substrate was fabricated via self-assembly of Ag NPs and graphene oxide. • GO/Ag SERS composite fiber substrate achieves 10 −11  M visual detection limit for 4-ATP and MG. • GO/Ag SERS substrate shows high uniformity, stability and 10.2% attenuation in 15 days. Surface-enhanced Raman scattering (SERS) has emerged as a powerful technique for ultrasensitive molecular detection. This study develops a SERS substrate based on graphene oxide‑silver (Ag/GO) composite optical fibers, enabling highly sensitive molecular detection. The graphene oxide layer promotes target molecule adsorption through π-π stacking interactions and surface oxygen functional groups, while providing antioxidant protection for silver nanoparticles. Performance characterization using 4-mercaptobenzoic acid (4-MBA) demonstrated excellent repeatability, uniformity, and temporal stability. In addition, the visual detection limit of 4-aminothiophenol (4-ATP) and malachite green (MG) on the fiber optic substrate reaches 10 −11  mol/L. Based on the criterion of signal-to-noise ratio S/N ≥ 3, the quantitative detection limits of the two are 1.93 × 10 −12  mol/L (4-ATP) and 3.8 × 10 −12  mol/L (MG), respectively. These results indicate the application potential of the Ag/GO-functionalized optical fiber SERS substrate in trace analysis. Environmental implication This study employs an Ag/GO composite fiber SERS substrate for the in-situ and rapid detection of malachite green (MG) and 4-ATP in water, without requiring large amounts of organic reagents or causing secondary pollution. MG and 4-ATP have high toxic, resistant to degradation, and prone to bioaccumulation, posing risks to aquatic organisms and accumulating along the food chain. This SERS substrate provides a green approach for early warning of trace pollutants in water environments, contributing to the safeguarding of water ecological security and pollution control. Download: Download high-res image (83KB) Download: Download full-size image