Graphene quantum dot-based hydrogel microspheres for sensitive detection of caffeic acid

In this investigation, blue-emitting graphene quantum dots (B,N-GQDs) were synthesized via a single-step hydrothermal method in an ethanol/water mixture utilizing 3-APBA as the nitrogen and boron sources. These B,NGQDs showcased a highly graphitized structure, complemented by surface-functionalized boronic acid and amino groups that bestowed upon them remarkable optical attributes and water solubility. Leveraging the interplay of internal filtering and dynamic quenching effects, the sensor demonstrated remarkable selectivity and sensitivity in detecting caffeic acid (CA) within the range of 0-840 mu M, achieving a limit of detection (LOD) of 0.63 mu M. Moreover, the fluorescent gel microspheres engineered with B,N-GQDs exhibited robust CA sensing capabilities and portability. As such, the application potential of B,N-GQDs expands to encompass drug metabolism monitoring, alongside the assessment of food and environmental safety.