An HIV virus with a diameter of 100 nm has 50 glycoprotein extrusions over its surface, each one of which will bind a 5-nm-diameter Ag nanoparticle. You are provided with a suspension of 5-nm-diameter Ag nanoparticles containing 1 μg Ag per milliliter of liquid. What volume of the suspension is required to saturate 10^7 viruses in a test tube?