Antioxidant activity and immunocompatibility of Maillard reaction carbon dots derived from arginine-glucose model system

The immunocompatibility and antioxidative characteristics of Maillard reaction-based carbon dots (MR-CDs) have not been extensively studied. This study aimed to develop a Maillard reaction model system utilizing glucose and arginine to synthesize carbon dots. The investigation into the MR-CD's physicochemical properties, biocompatibility, cytoprotective effects, and antioxidant capacity revealed promising results. TEM images showed spherical carbon dots (CDs) of 3-15 nm diameter. The FTIR spectra indicated the presence of hydroxyl, amino, and carbonyl functional groups in MR-CDs surfaces. An X-ray diffractometer analysis showed that CDs are amorphous. The fluorescence spectra revealed wavelength-dependent emission with a maximum intensity of 390 nm. The response of THP-1 cells after exposure to MR-CDs was studied to assess biocompatibility, nuclear morphology, ROS levels, lysosome accumulation, and gene expression of inflammatory markers (IL6, TNF alpha, NF kappa B, MIF, IFNA, and GSR genes). MR-CDs induced a dose-dependent proliferation of THP-1 cells without altering their nuclear morphology. A lysosome and mitochondrial membrane potential analysis also showed that MR-CDs are non-toxic. The levels of intracellular ROS did not differ from those in the control. Downregulation of inflammatory genes was observed after exposure to MR-CDs. The expression of the Glutathione-disulfide reductase (GSR) gene was upregulated in a dose-dependent manner, indicating increased antioxidant activity in MR-CDs. The result of the DPPH assay confirmed the antioxidant ability of MR-CDs. MR-CDs performed cytoprotective effects against hydrogen peroxide-induced cell damage. These findings suggest that, besides their immunocompatibility, MR-CDs possess potent antioxidant and cytoprotective properties, which make them ideal for a range of immunomodulatory applications, sparking optimism for future research and development in this field.