Disclosed herein is a nanoparticle modified fluid that includes nanoparticles that are surface modified to increase a viscosity of the nanoparticle modified fluid and that have at least one dimension that is less than or equal to about 50 nanometers; nanoparticles that are surface modified to increase a viscosity of the nanoparticle modified fluid and that have at least one dimension that is less than or equal to about 70 nanometers; and a liquid carrier; wherein the nanoparticle modified fluid exhibits a viscosity above that of a comparative nanoparticle modified fluid that contains the same nanoparticles but whose surfaces are not modified, when both nanoparticle modified fluids are tested at the same shear rate and temperature.