Synthesis, Properties and Applications of Silica-Coated Magnetite Nanoparticles: A Review

Silica-Coated Magnetite nanoparticles (SMNP) recently gained much attractions in biomedical, environmental, construction and nuclear applications. SMNP can overcome the limitations of bare magnetic iron oxide nanoparticles (MNP) such as agglomeration, dissolution and leaching in aqueous and biological system. Silica coating protects the MNP core as well as provides excellent biocompatibility, chemical and thermal stability with higher adsorption capacity of heavy metals and radionuclides. SMNPs are mostly prepared by Modified Stöber method as the simplest route although surface pretreatment or surface modification is needed to avoid formation of large aggregates. Microemulsion method gives excellent size and shape control but needs large quantity of surfactants and solvents. Sonochemical approach provides faster hydrolysis and can prevent agglomeration without any surface pretreatment. Optimal silica coating thickness can provide uniform particles distribution, enough superparamagnetic properties for easy magnetic separation, chemical and thermal stability. Keeping in mind the wide interest in SMNP, this review is designed to report the important information on synthesis, properties and potential applications of SMNP.