▎ 摘　　要

NOVELTY - Biocompatible composition comprises graphene quantum dots (GQDs) with a particle size of 5-10 nm embedded in polyethylene glycol (PEG) matrix with a particle size of 80-100 nm. USE - Biocompatible composition used for drug delivery and biomedical applications (all claimed). ADVANTAGE - The biocompatible composition has reduced cytotoxicity, thus, making it convenient for application in drug delivery, bioimaging and other biomedical applications. It is prepared by a simple electrochemical method and simple one step hydrothermal reaction. The PEG matrix aids in reducing the reactive oxygen radicals (ROS) generated by the GQD surface while keeping the small GQDs inside the matrix; thus, reducing their undesirable interactions with cellular proteins and organelles. The PEG-GQDs formed after hydrothermal reaction show nanoparticles of diameter of 80-100 nm containing GQDs entrapped in PEG matrix. The composition of PEG-GQD at a concentration of 8 mg/ml shows up to 50% cell viability when tested on HeLa cell lines. The biocompatible composition has ROS quenching ability, and thus, reduces the cytotoxicity even at higher concentrations. Biocompatible PEG-GQDs can be obtained in very short span of time with minimal use of hazardous chemicals and simple methodology. The cytotoxicity of GQDs were assessed using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay i.e. colorimetric assay to measure the mitochondrial activity that reflected the population of viable cells present. At 5.5 mg/ml concentration of GQDs, almost 60% cells were viable for PEG-GQDs, while only 5-10% were viable for crude-GQDs and hydrothermally treated-GQDs. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of biocompatible composition comprising electrochemical etching of multiwalled carbon nanotubes at 25-28 degrees C for 11-12 hours to provide GQDs of size 5-10 nm; mixing GQDs with polyethylene glycol followed by sonicating at 20-35 degrees C for 25-30 minutes to obtain a solution; autoclaving the solution at 140-180 degrees C for 23-24 hours; and cooling at room temperature of 20-35 degrees C followed by dialyzing to obtain biocompatible composition.