Department of Radiology, The First Affiliated Hospital of Soochow University , Suzhou, Jiangsu 215006, China.
ACS Appl Mater Interfaces. 2013 Oct 23;5(20):10381-8. doi: 10.1021/am403554x. Epub 2013 Oct 10.
Upconversion nanoparticles (UCNPs) have been widely explored for various bioapplications because of their unique optical properties, easy surface functionalization, and low cytotoxicity. Herein, we synthesize gadolinium (Gd3+)-doped UCNPs, which are modified first with poly(ethylene glycol) (PEG) and then with two layers of poly(ethylenimine) (PEI) via covalent conjugation and layer-by-layer assembly, respectively. Compared with UCNP-PEG@1×PEI with only one layer of PEI coating, the final complex, UCNP-PEG@2×PEI, with two PEI layers exhibits reduced cytotoxicity and enhanced gene transfection efficiency. It is interesting to find that while free PEI polymer is only effective in gene transfection in a serum-free medium and shows drastically reduced transfection ability if serum is added, UCNP-PEG@2×PEI is able to transfect cells in both serum-free and -containing media and, surprisingly, offers even higher gene transfection efficiency if serum is added. This is likely due to the formation of protein corona on the nanoparticle surface, which triggers the receptor-mediated endocytosis of our UCNP vectors. Considering the upconversion luminescence and magnetic resonance imaging contrasting ability of UCNPs, our novel nanovector could serve as a "trackable" gene-delivery carrier promising for theranostic applications.
上转换纳米粒子（UCNPs）由于其独特的光学性质、易于表面功能化和低细胞毒性而被广泛探索用于各种生物应用。在此，我们合成了掺钆（Gd3+）的 UCNPs，首先通过共价键合将其用聚乙二醇（PEG）进行修饰，然后通过层层组装分别用两层聚亚乙基亚胺（PEI）进行修饰。与仅具有一层 PEI 涂层的 UCNP-PEG@1×PEI 相比，最终的复合物 UCNP-PEG@2×PEI，具有两层 PEI，表现出更低的细胞毒性和更高的基因转染效率。有趣的是，发现虽然游离的 PEI 聚合物仅在无血清培养基中对基因转染有效，如果添加血清，则其转染能力会大大降低，而 UCNP-PEG@2×PEI 能够在无血清和含血清的培养基中转染细胞，如果添加血清，甚至会提供更高的基因转染效率。这可能是由于纳米粒子表面形成了蛋白质冠，触发了我们的 UCNP 载体的受体介导的内吞作用。考虑到 UCNPs 的上转换发光和磁共振成像对比能力，我们的新型纳米载体可以作为一种有前途的治疗诊断应用的“可跟踪”基因递送载体。
