Harigabri-Derived Carbon Dots as FRET Probes for E. coli Analysis

Green-fluorescent carbon quantum dots (CQDs) were hydrothermally synthesized from the Mongolian medicine Harigabri, exhibiting uniform size (∼2.5 nm) and strong emission at 521 nm under 468 nm excitation. Based on the fluorescence resonance energy transfer (FRET) between the CQDs (donors) and AgNPs (acceptors), an aptamer-functionalized biosensor (Apt-CQDs/AgNPs) was constructed for selective Escherichia coli detection. Target recognition by the aptamer inhibited FRET and restored fluorescence. The sensor showed a linear response from 9 × 102 to 9 × 107 CFU/mL with a detection limit of 5 CFU/mL. This work highlights Harigabri-derived CQDs as promising nanomaterials for rapid pathogen detection and demonstrates the potential of traditional medicinal resources in biosensing applications.