The Preparation Of Poly-L-Lysine-Silica Nanopartical As Gene Carriers And In Vitro Study Of Its Transfection Into Cells

With the development of nanobiotechnology, nanoparticles, as non-viral vectors, provide new and promising aspects as gene transfer vehicles. Inorganic nanoparticles have the potential to overcome systemic barriers to build drugs or DNA through appropriate surface modification and drug targeting becomes possible. Among the nanoparticles, amorphous silica nanoparticles are favoured since SiO2 is a nontoxic compound present in a lot of systemes, which can be tailored with a variety of surface modifiers, allowing adjusting properties like surface reactivity.Objective To prepare the poly-L-lysine-silica nanoparticles and investigate the transfection efficacy of the nanoparticles as gene carrier into cells.Method In the first part of our studies, an organical mordification method was applied to prepare the uniform silica nanoparticles (SiNP). The preparation was carried out in a water-in-oil (W/O) microemulsion containing polyoxyethylene nonylphenol ether, n-hexanol, cyclohexane and adequate water by controlling cohydrolysis of tetraethyl orthosilicate. Then poly-L-lysine (PLL) was linked on the surface of SiNP by nanoparticle surface energy and electrostatically binding, a novel complex nanomaterial poly-L-lysine-silica nanoparticles (PLL-SiNP) was prepared.In the second part of our studies, the poly-L-lysine-silica nanoparticles -DNA complexes can be easily formed through electrostatical binding due to the presence of amino group on the surface of the nanoparticles. The PLL-SiNP binding ability to DNA was studied with the electrophoretic mobility assays.In the third part, the silica nanoparticles-DNA conjugated with the enhanced green fluorescence protein DNA plasmid (pEGFP -C1) was transfected into HepG2 and LO2. The expression of green fluorescence protein was investigated in transfected cells by fluoromicroscopy examine and the efficiency of gene transfection was revealed.Results The uniform silica nanoparticles was sucssesfully prepared. The nanoparticles were spherical and uniform in size, about 30 nm in diameter, and highly monodispersed, stable aqueous suspension of nanoparticles. Surface-functionalized with polylysine had the good ability of binding DNA. The nanoparticle/DNA ratio of 30(w/w) was found to be optimal from the results of the electrophoretic mobility assays. The silica nanoparticles-pEGFP-C1 complexes at a ratio of 30(w/w) can be effectively transfected into HepG2 and LO2. The efficiency of gene transfection by silica nanoparticles were 35.1% and 34.0%, which were equivalency with that of liposome(P>5%).Conclusion The PLL-SiNP nanoparticles has been prepared, it could be used as DNA carriers for gene transfection such as pEGFP-C1.