Supramolecular calix[6]arene-COF with pocket-like cavities for host-guest recognition-based SERS detection of tryptamine and seafood freshness monitoring

Monitoring seafood freshness is critical for ensuring nutritional value and food quality, but targeted analysis in complex matrices remains challenging. Herein, a thiol-functionalized calix[6]arene covalent organic framework grafted with AuNPs, denoted as CX6-SCOF-AuNPs, was strategically designed for rapid, sensitive and selective detection of tryptamine in seafood by surface-enhanced Raman spectroscopy (SERS). CX6-SCOF-AuNPs featured extensive pocket-like hydrophobic cavities integrated within an ordered porous structure, enabling specific capture of tryptamine with exceptional enrichment capacity (203.4 mg/g) and rapid adsorption kinetics (within 2 min). The selectivity mechanism stemmed from the formation of a ground-state charge-transfer complex driven by specific “pocket effect” between CX6-SCOF and size-matched tryptamine. CX6-SCOF-AuNPs was successfully applied to enrichment and detection of tryptamine in seafood, achieving high sensitivity (LOD of 3.4 μg/L) and satisfactory recoveries (90.6 % – 107.4 %). This work provides a promising strategy for supramolecular recognition and targeted SERS analysis of trace hazards in complex food matrices.