Synthesis of protein-gold nanoparticle hybrid and gold nanoplates in protein aggregates

► Gold nanocrystals were synthesized by using casein micelles without additional reductant. ► GNP and gold nanoplates in good yields were obtained by adjusting the experimental condition. ► The high colloidal stability of the spherical GNP is attributed to the formation of CM/GNP hybrid. ► Nanocrystals growth is caused by the faceting tendency of the protein and the growth kinetics.