An evaluation of carbon dots derived from Amaranthus tricolor (L.) leaves for their physicochemical, photoluminescent, and biomedical properties

Abstract This study explores the synthesis, characterization, and bio-functional potential of carbon dots (CDs) derived from Amaranthus tricolor (AT-CDs). Phytochemical analysis confirmed the presence of bioactive compounds while quantitative assays revealed a TPC of 157.2 ± 8 mg TAE/g extract and TFC of 457.4 ± 38 mg quercetin/g extract. AT-CDs exhibited a characteristic UV–Vis absorption peak at 317 nm, with fluorescence spectra showing excitation-dependent emission. FTIR analysis identified presence of key functional groups like –OH, –C = O, and –CN, corroborating the bioactive surface chemistry. DLS indicated a Z-average particle size of 214.4 nm, while zeta potential measurements (67.7 mV) confirmed high colloidal stability. TEM analysis revealed a uniform size distribution with a mean particle size of 3.2 ± 0.02 nm. Antioxidant assays demonstrated IC 50 values of 67.36 µg mL −1 for DPPH and 360.65 µg mL −1 for H 2 O 2 scavenging, reflecting concentration-dependent radical neutralization. Coagulation assays showed a significant prolongation of prothrombin time (55 s) and activated partial thromboplastin time (58 s) at 200 µg mL −1 , highlighting anticoagulant potential. These findings suggest that AT-CDs, with their multifunctional properties and bioactivity, are promising candidates for biomedical applications, particularly in oxidative stress management, drug delivery, and haemostasis modulation. Graphical abstract