Institute of Experimental Oncology and Therapy Research, Klinikum rechts der Isar der Technischen Universität München, Ismaningerstrasse 22, 81675 Munich, Germany.
Pharm Res. 2012 May;29(5):1344-65. doi: 10.1007/s11095-011-0661-9. Epub 2012 Jan 6.
To optimize silica-iron oxide magnetic nanoparticles with surface phosphonate groups decorated with 25-kD branched polyethylenimine (PEI) for gene delivery.
Surface composition, charge, colloidal stabilities, associations with adenovirus, magneto-tranduction efficiencies, cell internalizations, in vitro toxicities and MRI relaxivities were tested for the particles decorated with varying amounts of PEI.
Moderate PEI-decoration of MNPs results in charge reversal and destabilization. Analysis of space and time resolved concentration changes during centrifugation clearly revealed that at >5% PEI loading flocculation gradually decreases and sufficient stabilization is achieved at >10%. The association with adenovirus occurred efficiently at levels over 5% PEI, resulting in the complexes stable in 50% FCS at a PEI-to-iron w/w ratio of ≥7%; the maximum magneto-transduction efficiency was achieved at 9-12% PEI. Primary silica iron oxide nanoparticles and those with 11.5% PEI demonstrated excellent r(2)* relaxivity values (>600 s(-1)(mM Fe)(-1)) for the free and cell-internalized particles.
Surface decoration of the silica-iron oxide nanoparticles with a PEI-to-iron w/w ratio of 10-12% yields stable aqueous suspensions, allows for efficient viral gene delivery and labeled cell detection by MRI.
用表面膦酸酯基团修饰的 25kD 支链聚乙烯亚胺（PEI）优化硅-氧化铁磁性纳米粒子，用于基因传递。
对不同 PEI 修饰量的粒子进行表面组成、电荷、胶体稳定性、与腺病毒的结合、磁转导效率、细胞内化、体外毒性和 MRI 弛豫率的测试。
适度的 PEI 修饰导致 MNPs 带正电和不稳定性。离心过程中空间和时间分辨浓度变化的分析清楚地表明，在 >5%PEI 负载时，絮凝逐渐减少，在 >10%时达到充分稳定。在超过 5%PEI 的水平上，与腺病毒的结合效率很高，导致复合物在 50%FCS 中稳定，PEI-铁 w/w 比≥7%；最大的磁转导效率在 9-12%PEI 时达到。原始的硅-氧化铁纳米粒子和具有 11.5%PEI 的粒子在游离和细胞内化粒子中表现出优异的 r(2)*弛豫率值（>600 s(-1)(mM Fe)(-1)）。
用 PEI-铁 w/w 比为 10-12%对硅-氧化铁纳米粒子进行表面修饰，可得到稳定的水性悬浮液，可实现高效的病毒基因传递和 MRI 标记细胞检测。
