▎ 摘　　要

In this work, we report the fabrication of green fluorescent reduced graphene oxide quantum dots (rGOQDs) from the latex of Calotropis gigantea by simple one-step microwave assisted greener route. The latex of Calotropis gigantea calcined at 300 degrees C and its ethanolic extract is used for the synthesis of QDs, The rGOQDs showed particle size ranging from 2 to 8 nm and it exhibited green fluorescent in longer UV region at 360-520 nm. The rGOQDs graphitic nature was confirmed by RAMAN and XRD analysis. The FTIR, XPS demonstrate that presence of functional groups such as C=O, C-O-C, OH, hence it's addressing them as rGOQDs. It is used to design the greener and economically adopted fluorescent probe for the detection of Pb2+ ions. It provides simple and appropriate for the selective and sensitive detection of Pb2+ ions in water purification process. It also trapped the free radicals and neutralized that and act as an excellent radical scavenger in DPPH radical scavenging assessment. These rGOQDs showed excellent biocompatibility on brine shrimp nauplii (Artemia salina) up to 160 mu g/mL for 24 h incubation. Furthermore, rGOQDS were demonstrated as fluorescent bioimaging probe selectively in the inner digestion part of Artemia salina. In summary, stable, economically viable, highly biocompatible, greener method based rGOQDs were prepared for heavy metal ion detecting, radical scavenging, bioimaging applications which can play a vital role in the future nanotechnology-based biomedical field.