Silane Coupling Agent Modification Of Fe <sub> 3 </ Sub> The O <sub> 4 </ Sub> Preparation Of Magnetic Nanoparticles As A Gene Vector Research

In recent years, the potential prospect of gene therapy as the way to replace the dysfunctional gene and to tackle the cancer has been widely investigated. One of the major problems to solve is how to develop a safe and effective gene delivery systems. During the process of the development, the obvious trend is that non-viral delivery systems for gene therapy have been increasingly proposed, having the potential to reduce the damages of the viral delivery systems to the healthy cells. With the development of nanotechnology, magnetic iron oxide nanoparticles provide new way for genetic carrier.In this work, Fe₃O₄ magnetic nanoparticles were prepared by thermal decomposition of Fe(acac)₃ in 2-pyrrolidone. The APTTS/Fe₃O₄ particles were prepared by Fe₃O₄ surface modification with 3-aminopropyl-triethoxysilane (APTTS). The potency of adsorbing DNA and resisting DNasel digestion of APTTS/Fe₃O₄ was analyzed by agarose gel electrophoresis. The green fluorescent protein-C2(GFP-C2) plasmid was used as target gene. The efficiencies of APTTS/Fe₃O₄ in transferring GFP gene into HL7702 and HT 1080 were evaluated under Flow Cytometer in vitro.The summarized conclusions of this paper are follows:(1)The magnetic nanoparticles synthesized in thermal decomposition method have a narrow particle size distribution (8-10nm), good crystallinity and high-quality magnetic. The predominant factors effect on performance of Fe₃O₄ are the reaction atmosphere, the reaction time and the content of reactants. It is shown that the optimal experimental conditions are the reflux time 30 minutes, the ratio of 2-pyrrolidone to Fe(acac)₃ is 10:1 (ml/mmol).(2) The amino-silane modified magnetite nanoparticles were synthesized by the coprecipitation and surface modification with 3-aminopropyl- triethoxysilane(APTTS). It was found that when the mol ratio of amino-silane and Fe₃O₄is 4:1, the mgnetic microspheres have a good stability, dispersibility and high-quality magnetic. Displaying functional group of-NH2, high saturation magnetization, the superparamagnetic APTTS-modified Fe₃O₄ nanoparticles are of significance for magnetic applications in biomedicine.(3) Adsorption and protection of DNA on magnetic nanoparticles was carried out. It is shown that the APTTS/Fe₃O₄ microspheres have the ability of binding DNA and resisting DNasel digestion. When the mass ratio of APTTS/Fe₃O₄ microspheres and DNA is 1:2, the binding efficiency is more than 90%. It was found that the magnetic microspheres had not cytotoxicity effect with the HL7702 and HT1080 cells. The survival rate of cells is about 95%. The efficiencies of APTTS/Fe₃O₄ in transferring EGFP-C2 gene into HL7702 and HT 1080 are 63.2% and 60%, higher than liposome's. Therefore, the APTTS/Fe₃O₄ magnetic nanoparticle is an ideal delivery vector in the gene transfer.