Gas-phase engineered gold-on-paper SERS substrates for quantitative thiabendazole sensing in real matrices

A three-dimensional (3D) Au nanoparticles (AuNPs)-cellulose interface was engineered via solvent-free spark ablation and direct particle deposition onto filter paper, forming a percolated junction network with abundant nanoscale gaps that enables surface-enhanced Raman scattering signal amplification under a fiber-optic probe geometry. The resulting 3D plasmonic network exhibits good signal reproducibility, as verified by Rhodamine 6G mapping (RSD 13.5-16.6%). Using thiabendazole (TBZ) as a representative small-molecule residue, the platform enables quantitative detection down to 0.08 ppm in methanol and 0.10 ppm in untreated apple juice, supporting residue monitoring in real matrices. A nonlinear logarithmic calibration model captures the concentration-dependent response without requiring complex chemometric processing. TBZ-spiked apple juice samples showed satisfactory recoveries of ca. 83-105%, while selectivity against thiram, batch-to-batch repeatability, and intra-/inter-day precision further confirm the analytical robustness of the engineered interface. Overall, the AuNP-cellulose junction network couples interface-driven signal amplification with point-of-need applicability, advancing flexible Raman-based sensing for rapid residue screening in food safety and related chemical/biosensing scenarios.