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In recent years, many studies have been performed on for use in various of science. The proper design and synthesis of these has a direct impact on their -chemical properties and their applications, especially in the field of biological sciences. There are several methods for magnetic synthesis. One of the simplest and most efficient methods for synthesis of magnetic is a chemical co-precipitation method, but of magnetic is one of the limitations of this method. In this study, various protocols for the synthesis of magnetic by co-precipitation method and silica coating of magnetic were performed and the effect of different factors such as the type of alkaline compound, the use of , temperature and in dispersion, aggregation of magnetic nanoparticles and their stability in aqueous solutions was investigated. Finally, a simple and reproducible protocol for magnetic synthesis with appropriate size distribution and high dispersion in aqueous solutions was optimized for use in biological applications.