We present an approach to tuning the multifunctionality of iron oxide nanoparticles (IONs) using mixed self-assembled monolayers of cationic lipid and anionic polyethylene glycol (PEG) lipid. By forming stable, monodispersed lipid-coated IONs (L-IONs) through a solvent-exchange technique, we were able to demonstrate the relationship between surface charge, the magnetic transverse relaxivity (r₂ from T₂-weighted images), and the binding capacity of small interfering ribonucleic acids (siRNAs) as a function of the cationic-to-anionic (PEG) lipid ratio. These properties were controlled by the cationic charge and the PEG conformation; relaxivity and siRNA binding could be varied in the mushroom and brush regimes but not at high brush densities. In vitro results combining cell viability, uptake, and transfection efficiency using HeLa cells suggest that the functional physicochemical and biological properties of L-IONs may be best achieved using catanionic lipid coatings near equimolar ratios of cationic to anionic PEG–lipids.

中文翻译：

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使用自组装混合脂质层调节氧化铁纳米颗粒的多功能性

我们提出了一种使用阳离子脂质和阴离子聚乙二醇（PEG）脂质的混合自组装单层膜来调节氧化铁纳米颗粒（IONs）多功能性的方法。通过溶剂交换技术形成稳定的，单分散的脂质包裹的离子（L-IONs），我们能够证明表面电荷与磁横向弛豫率之间的关系（r ₂来自T ₂加权图像），以及小干扰核糖核酸（siRNA）的结合能力随阳离子与阴离子（PEG）脂质比率的变化而变化。这些性质是由阳离子电荷和PEG构象控制的。松散度和siRNA结合在蘑菇和刷子方式下可能会有所不同，但在高刷子密度下则不会。结合使用HeLa细胞的细胞活力，摄取和转染效率的体外结果表明，使用等摩尔比例的阳离子与阴离子PEG-脂质的阳离子脂质涂层可以最好地实现L-IONs的功能物理化学和生物学特性。