For the synthesis of silica coated cobalt-ferrite ferrofluid an aliquot of the uncoated nanoparticles is added at room temperature to a mixture of water and 2-propanol. Ammonia water solution and TEOS are consecutively added and this procedure is repeated for a number of times so that the final thickness of the shell comes to 2 nm assuming that all the nanoparticles would be covered by a uniform coating. The core-shell nanoparticles are then separated from the reaction medium and then dispersed in water.

Uncoated FF + H2O+2-Propyl Alcohol +NH4OH TEOS + Centrifuge= Silica Coated FF

Silica-coated magnetic ferrofluids can also be successfully synthesized by coating cobalt ferrite magnetic nanoparticles.