Exploring the proton-anion synergism in boosting SERS performance for tobramycin: from mechanism to sensitive detection

A Proton-Anion Synergism (PAS) creates three-dimensional H-bonded hotspots on AgNPs for SERS. • The PAS strategy achieves enhancement factor of 1.7 × 10 6 for tobramycin. • Ultra-low limit of detection of 8.03 × 10 −11 M is achieved. • The assay enables rapid milk testing with 88.17–106.03% recoveries. A novel surface-enhanced Raman scattering (SERS) strategy based on a Proton-Anion Synergism (PAS) mechanism is proposed for the rapid and sensitive detection of tobramycin (TOB). In this mechanism, H + from HNO₃ protonates the amino groups of TOB to form NH₃ + , while NO₃ − acts as a hydrogen-bond acceptor, establishing N H···O interactions with the protonated TOB. This synergistic effect induces the formation of a dense three-dimensional hydrogen-bonded network on AgNPs, generating abundant SERS hot spots and strong signal amplification. The SERS intensity at 1024 cm −1 showed a good linear relationship with the logarithm of TOB concentration over the range of 10 −9 to 10 −5 M (R 2  = 0.986), with a limit of detection of 8.03 × 10 −11 M and an enhancement factor of 1.7 × 10 6 . The method exhibited excellent selectivity for TOB over other common antibiotics and good reproducibility (RSD = 4.05%). Recovery tests in spiked milk samples ranged from 88.17% to 106.03%. This PAS-based SERS platform is simple, cost-effective, and rapid, showing great potential for detecting TOB and other aminoglycoside antibiotics in real-world samples. Download: Download high-res image (203KB) Download: Download full-size image