MRI-visible liposome-polyethylenimine complexes for DNA delivery: preparation and evaluation.

To noninvasively monitor the effect of gene therapy and achieve an optimal therapeutic effect, liposomes encapsulated polyethylenimine (PEI)-coated superparamagnetic iron oxide nanoparticles (SPION) with dual functions of MRI diagnosis and gene therapy were prepared. SPION was synthesized via co-precipitation, and then modified with PEI via thiourea reaction. The liposomes encapsulating PEI-SPION (LP-PEI-SPION) were prepared by ethanol injection. Fourier transform infrared spectra confirmed that PEI was successfully modified onto SPION, and thermogravimetric analysis indicated that the PEI content was about 17.1%. The LP-PEI-SPION/DNA had a small particle size of 253.07 ± 0.90 nm. LP-PEI-SPION/DNA had low cytotoxicity with more than 80% of the cell survival rates and high transfection efficiency compared with Lipofectamine® 2000/DNA. Additionally, it also showed good MRI effect on three cell lines. The liposomes encapsulating PEI-SPION (lipopolyplexes) have been successfully prepared as MRI contrast agents and gene delivery vectors, which may have great theoretical research significance and clinical potentials. Abbreviations: PEI, polyethylenimine; SPION, superparamagnetic iron oxide nanoparticles; LP-PEI-SPION, liposomes encapsulating PEI-SPION; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; ICP-MS, inductively coupled plasma mass spectrometry; XRD, X-ray diffraction; TEM, transmission electron microscope; TGA, thermogravimetric analysis; DOTAP, 1,2-dioleoyl-3-trimethylammonium-propane; DOPE, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine; Chol, cholesterol.