Sea-urchin-like gold nanoparticles meet polymer-grafted nanotubes: A robust interfacial co-assembled SERS film for antibiotic sensing

Liquid-liquid interfacial co-assembly yields uniform and large-area nanofilms. • Urchin-like GNPs provide tip-enhanced hotspots for superior SERS sensitivity. • CNT-g-P4VP hybrid offers robust mechanical support and molecular enrichment capability. • The nanofilm achieves 10⁻¹ ² M detection limit with excellent signal reproducibility. • The nanofilm enables sensitive, quantitative detection of diverse antibiotics. The sensitive and reliable detection of antibiotic residues is important for food safety, environmental monitoring, and public health. In this work, a robust surface-enhanced Raman scattering (SERS) platform was developed through the liqud-liquid interfacial co-assembly of poly(4-vinylpyridine)-grafted carbon nanotubes (CNT- g -P4VP) and sea urchin-like gold nanoparticles (SUGNPs). Unlike previously reported antibiotic-oriented SERS systems that mainly emphasize either ultralow detection limits, matrix-specific analysis, or mechanical reinforcement, the present design integrates morphology-amplified plasmonic hotspots with a transferable and mechanically reinforced nanofilm in a single assembly process. The key advance is that tip-rich SUGNPs are incorporated into the CNT- g -P4VP scaffold without sacrificing film continuity, thereby producing substantially stronger SERS signals than an identically assembled spherical-AuNP control. The sharp SUGNP tips and interparticle junctions provide intense electromagnetic enhancement, while the CNT- g -P4VP network anchors the particles, maintains film integrity, and may assist analyte association near the plasmonic regions. Using 4-mercaptobenzoic acid as a probe, the substrate achieved a detection limit of 10 −12 M and a relative standard deviation of 4.3%. Clearly identifiable SERS signals were retained after 100 bending cycles and after 3 months of ambient storage. Sulfacetamide and cephalexin were detected down to 10 −8 M with RSD values of 5.72% and 7.97%, respectively, and their molecular fingerprints remained recognizable in pretreated lake water. Thus, this work advances the field by demonstrating a morphology-engineered, transferable SERS film that balances sensitivity, reproducibility, mechanical durability, and matrix applicability rather than improving only a single analytical metric. Download: Download high-res image (246KB) Download: Download full-size image