Acid-stabilized iron-based metal oxide colloidal nanoparticles, and methods thereof

Abstract

Size-controlled ultra-small iron-based metal oxide nanoparticles, nanocolloids comprising the nanoparticles, and methods of making the nanoparticles. The method for making the iron-based nanoparticles include sequential mixing of an iron(III) salt, a metal (II) salt, a carboxylic acid, an amine, and an inorganic base in water at temperatures ranging from 25-80° C. Nanoparticles in the size ranging from 2 nm to 10 nm with a narrow size distribution are obtained with the method. The nanoparticles have an iron-based core surrounded by molecules such as a panel of different carboxylates, polycarboxylates, and amines. Depending on the hydrophilicity of the carboxylates used, the functional nanoparticulate colloid can be dispersed in either organic or aqueous solvents. The nanocolloids comprise the nanoparticles in a concentration ranging from 1-10 mg/ml, and are stable for at least several months.