▎ 摘　　要

NOVELTY - A graphene-coated magnetic composite nanomaterial comprises graphene as a shell, and gold-cobalt alloy as a core-shell structure. The graphene is directly wrapped on the surface of the gold-cobalt alloy. The magnetic composite nanomaterial is granular, and has particle size of 20-40 nm. USE - Graphene-coated magnetic composite nanomaterial for use in biological imaging application (claimed). ADVANTAGE - The graphene-coated magnetic composite nanomaterial is prepared by simple process at low cost in a controlled manner with high homogeneity, and stability. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of graphene-coated magnetic composite nanomaterial, which involves (i) adding silica to methanol solution in a ratio of 1:80-100 g/ml, ultrasonically processing for 1-2 hours to obtain solution (A), mixing cobalt nitrate hexahydrate with 5-20 mg/ml tetrachloroauric acid solution to obtain solution (B), mixing 40-60 parts mass solution (A) and 1 part mass solution (B), ultrasonically processing for 1-2 hours, removing methanol, and drying the mixture, (ii) grinding the dried mixture into a powder, passing methane at a flow rate of 10-60 cm2/ml, burning at 800-1000 degrees C for 10-15 minutes, cooling, mixing with hydrogen fluoride solution, and separating solution from the solid.