Preparation And Characteristics Of Iron Oxide Nanoparticles Modified By Amino Silane And Bovine Serum Albumin Adsorption

Magnetic nanoparticle is a composite particle that composed of magneticmetal or oxide with magnetic responsive property. Magnetite (Fe₃O₄) was characteristic of small scale effect, quanta effect and peculiar superpara magnetism. Magnetic nanoparticle could be dispersed in liquid phase, thus forming magnetic fluids, which qualified with fluidity and magnetism, and be widely used in biomedicine field, such as cellular therapy (cell labeling, targeting and separation), tissue repair, drug delivery, magnetic resonance imaging (MRI), hyperthermia and so on. In this paper, ultrafine iron oxide nanoparticles were prepared in alkaline solution by chemical co-precipitation method, then modification was carried out by amino silane KH550, adsorption of bovine serum albumin on surface of magnetic particles were studied after KH550 wrapped.Firstly, iron oxide was prepared by adding ammonia to an aqueous mixture of Fe²⁺ and Fe³⁺ chloride with nitrogen protection, the precipitated is black in color. The results indicate that the prepared powder is Fe₃O₄ , which is paramagnetic , with a diameter of 30 nanometer. Amino silane could hydrolyze when it was dissolved in solution, so we synthesized the Fe₃O₄/KH550 compound powder by polymerizing hydroxyl between nanoparticles and 3-aminopropyl-triethoxysilane. The experimental results show that magnetic nanoparticles were well dispersed and stabilized with a small decrease of the magnetic saturation after modification, chemistry coupling existed between KH550 and Fe₃O₄ and -NH₂ were introduced to surface of Fe₃O₄, which could have a further use, such as the linkage of protein, DNA and antibody.Adsorption of bovine serum albumin on surface of magnetic particles were studied in the presence of silane coupling KH550 in phosphate buffer salt (PBS, pH7.4), the content of amino silane, reaction time, the original concentration of BSA and other interrelated factors were discussed in this paper. We summarize that the process of adsorption is rather rapid and the amount of BSA on surface of pure Fe₃O₄ is 17mg/g after 30 minutes, on the other hand the amount is 65mg/g on surface of KH550 wrapped Fe₃O₄, the adsorption amount increased as BSA original concentration increased. The capability of hydrophile improved after modification and the contact angle fell from 63 degree to 16 degree, at the same time the magnetic characteristics had a small decrease, so the magnetic compound powder can be separated promptly and used as target carrier. Cell culture result indicate that pure Fe₃O₄ is disadvantageous for MC 3T3-E1 cell proliferation; the cell growth had a faint influence after introduction of KH550, the biocompatibility of magnetic nanoparticle was improved when the adsorption of bovine serum albumin was carried out.