Bio-derived intelligent packaging platform: Starch-Stabilised N,S-Co-Doped carbon nanodots with enhanced photostability for selective tetracycline detection

초록

Rapid on-site detection of antibiotic residues in food matrices remains a critical challenge for food safety assurance. Carbon nanodot (CD)-based fluorescent sensors have emerged as promising candidates for rapid analytical sensing due to their exceptional optical properties. However, the conventional liquid-state CD sensors suffer from inherent photostability limitations that critically hinder their practical packaging applications. Herein, we engineered a novel matrix-stabilised biodegradable solid-state intelligent packaging platform using corn silk-derived nitrogen-and sulfur-co-doped CDs (N,S-CDs) embedded into an extruded potato starch (ePS) matrix via a scalable extrusion process. This nanocomposite film significantly enhanced photostability, potentially due to intermolecular hydrogen-bonding interactions between starch chains and N,S-CDs, thereby overcoming the quenching issues typical of liquid-phase sensors. The N,S-CDs exhibited high biocompatibility, maintaining HepG2 cell viability above 90%. Furthermore, the developed sensing platform displayed selective quenching response to tetracycline over 25 antibiotics and metal ions tested. The nanocomposite exhibited linear quenching over the 0-60 mu M range (R2 = 0.993) with a limit of detection of 0.12 mu M, demonstrating high sensitivity. A series of photophysical analyses confirmed that the primary inner filter effect was the major quenching mechanism. Practical validation in milk and tap water demonstrated excellent recoveries (96.84-107.26%) and precision (RSD <= 7.51%). These findings demonstrate proof of concept for sustainable intelligent food packaging systems, offering a scalable and field-deployable solution for on-site antibiotic monitoring in food safety and quality control.

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