Luminescent solid-state carbon dots synthesized based on the one-step hydrothermal method for the immobilization of α-glucosidase and imaging screening of enzyme inhibitors

Modern pharmacology studies have demonstrated that α-glucosidase is closely associated with a variety of metabolic disorders. Natural herbs have emerged as possible sources of α-glucosidase inhibitors (AGIs) in recent years. Thus far, highly selective screening of biologically active chemicals in complicated mixtures using ligand fishing approaches has not been able to achieve biomedical imaging, which is critical for real-time identification. Hence, this paper presented a novel technique for screening potential AGIs in Scutellaria baicalensis by utilizing fluorescent carbon dots that have been immobilized with α-glucosidase (α-glu-NH2-CDs). The synthesized carbon dots materials exhibited excellent fluorescence properties, biocompatibility, and an abundance of functional groups, as demonstrated by the utilization of several techniques. The activity of α-glucosidase covalently linked to the material under ideal immobilization conditions was 86.81% of that of the free form. The immobilized α-glucosidase also exhibited great temperature stability, pH stability and reusability according to an examination of its enzymatic characteristics. As a result, three ligands were identified as potential AGIs, i.e., baicalein, wogonin and scullcapflavone II by UPLC-MS/MS. The molecular docking and enzyme inhibition test indicated that the isolated compounds exhibited significant α-glucosidase inhibitory activities. Moreover, the proliferation inhibitory activity of the screened ligands on HCT-116 cells was further verified morphologically using in situ imaging technique. These results strongly suggested that the established method, which combined ligand fishing with in situ visual imaging, not only screen and separate the potential AGIs in Scutellaria baicalensis quickly and effectively, but also provide an effective platform for screening bioactive compounds on different receptors.