Novel blue-pea flowers derived-carbon dots/iron oxide nanohybrid as sustainable "turn-off" fluorescent nanosensor for selective Fe3+ detection in food samples.

Developing a novel fluorescence carbon-based sensor with high sensitivity, selectivity, and rapid response is critical for detecting ferric ion (Fe3+) in beverages and food products. Overcoming this challenge is essential, as excess Fe3+ 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 Fe3+, 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 Fe3+, remaining unaffected by various interferences, including common metal ions and small organic molecules. Upon Fe3+ 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 Fe3+ 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 Fe3+ detection, unaffected by matrix interference. These qualities make them promising candidates for advanced detection applications in food products, ensuring food safety.