Synthesis of Iron Oxide Nanoparticles Optimized by Design of Experiments

Magnetic iron oxide nanoparticles have been widely studied for technological and biomedical applications due to its small size and the possibility of functionalizing the surface with intended molecules. Magnetite is the most used phase because of superparamagnetic characteristic, and it is synthesized by co-precipitation, starting from ferrous and ferric ions in alkaline media. However, depending on parameters of chemical reactions, such as molar ratio between iron and hydroxyl groups, stirring rate, and temperature, different iron oxide structures are formed through distinct pathways. Since several variables can affect the size, chemical composition, and crystalline structure of iron oxide nanoparticles during the synthesis, it is very important to apply experimental routines with a well-defined protocol and planning practical steps can significantly improve the quality of products. Plackett-Burman methodology from design of experiments is a filtration analysis, used in the initial stages of a process to investigate the main effects of factors over a characteristic of the final material. In this work, Plackett-Burman technique was employed in order to optimize bare iron oxide nanoparticle production by co-precipitation method, relating the different crystalline phases produced to the experimental routine. Dynamic light scattering, Fourier transform infrared spectroscopy, and X-ray diffractometry were used to characterize the samples.