The preparation of a magnetic gene and drug vector and its application in heat-inducible gene expression

In somatic gene therapy, new concepts for the transfer of DNA into specific cell nucler are of interest. In this study, the feasibility of using magnetic nanoparticles with chemotherapeutant (PEI-As₂O₃/ Mn_0.5Zn_0.5Fe₂O₄) as gene vector is evaluated. Mn_0.5Zn_0.5Fe₂O₄ magnetic nanoparticles(MZF-NPs), obtained through co-precipitation method, were firstly combined with As₂O₃ to prepare As₂O₃/Mn_0.5Zn_0.5-Fe₂O₄ complex by the impregnation process. Then As₂O₃/Mn_0.5Zn_0.5Fe₂O₄ was modified by polyethyleneimine (PEI) and characterized by SEM (scanning electron microscope), FTIR(fourier transform infrared spectroscopy), EDS (energy dispersive spectrometer) and atom fluorescence spectrophotometer, respectively. Thermodynamic test of the same doses of MZF-NPs and PEI-As₂O₃/Mn_0.5Zn_0.5Fe₂O₄ was preformed in vitro. As a gene vector, the DNA binding efficiency, and transfection ability of it were tested. To evaluate the heat- induced gene expression under an alternating magnetic field (AMF), we combined P1730OR plasmid transfection with energy produced by irradiation of MZF-NPs. The results indicate that PEI-As₂O₃/Mn_0.5Zn_0.5Fe₂O₄ has been synthesized successfully, and presents good dispersibility. And As could release gradually from PEIAs₂O₃/ Mn_0.5Zn_0.5Fe₂O₄. In AMF, it can rise to the same temperature as MZF-NPs. It shows good DNA binding ability and can transfer foreign gene into HepG 2 cells. By using LacZ gene as a reporter gene and Hsp70 as a promoter, it was demonstrated that expression of β-gal rose as the temperatur- - e increased, which could reach to peak at 43.5°C. As action time prolongation, the expression of β-gal first added and then decreased, which reached to peak at the time point of 24h. This novel system made use of heat produced by Mn_0.5Zn_0.5Fe₂O₄ to regulate the expression of target gene, and As₂O₃ can act as the effect of chemotherapy.