The invention provides stabilized, biocompatible gold nanoparticles that are stabilized with material from soy or lentil plant material or a reactive extract thereof of the plant material. The gold nanoparticles of the invention can be fabricated with an environmentally friendly method for making biocompatible stabilized gold nanoparticles. The nanoparticles can be introduced in vivo to conduct enhanced imaging. The nanoparticles can also be introduced in vivo to conduct therapy.