Novel blue-pea flowers derived-carbon dots/iron oxide nanohybrid as sustainable "turn-off" fluorescent nanosensor for selective Fe detection in food samples.

Developing a novel fluorescence carbon-based sensor with high sensitivity, selectivity, and rapid response is critical for detecting ferric ion (Fe) in beverages and food products. Overcoming this challenge is essential, as excess Fe can cause cellular damage, raising health concerns. Herein, we designed a fluorescence nanosensor utilizing a hybrid iron oxide/carbon dots (HICs) nanocomposite, synthesized from blue pea (BPs) flowers and iron oxide nanoparticles through a hydrothermal treatment. More importantly, the HICs demonstrated high sensitivity and a rapid response to Fe, with a linear detection range spanning 0.06 to 100 µM and an impressively low limit of detection (LOD) of 13.61 nM. Moreover, the HICs exhibited remarkable selectivity toward Fe, remaining unaffected by various interferences, including common metal ions and small organic molecules. Upon Fe addition, the fluorescence quenching of HICs occurs through a combination of static quenching and dynamic quenching mechanism and the inner filter effect. Additionally, the detection of Fe in milk and herbal drinks was achieved using HICs, yielding satisfactory recovery rates ranging from 94.4 % to 103.7 %. Thus, the developed HICs serve as highly efficient "turn-off'" fluorescent nanosensors, exhibiting a rapid response, high sensitivity, and ultra-selectivity for Fe detection, unaffected by matrix interference. These qualities make them promising candidates for advanced detection applications in food products, ensuring food safety.