A multiparametric study of gold nanoparticles cytotoxicity, internalization and permeability using an in vitro model of blood–brain barrier. Influence of size, shape and capping agent

Gold nanoparticles (AuNPs) have biomedical application on imaging and due to increased optical performance, star-shaped AuNPs are of special interest. Because shape, size and capping greatly influence their toxicokinetics and toxicodynamics, a systematic multiparametric comparative study of the influence of these parameters on the cytotoxicity, internalization, and in vitro permeability was conducted in human Cerebral Microvascular Endothelial Cell line (hCMEC/D3), an in vitro model of the human blood-brain barrier (BBB). AuNPs of different size (14 nm and ∼50 nm), shape (spheres and stars), and coating (11-mercaptoundecanoic acid or MUA and sodium citrate) were synthesized and fully characterized. The time- and concentration-dependent cytotoxic profile of the tested AuNPs differed for the different AuNPs. Generally, toxicity was greater for stars relative to sphere-shaped AuNPs, and citrate coating was more toxic than MUA. Regarding the influence of size, smaller-sized AuNPs were more cytotoxic when compared at the same Au concentration. However, when the concentration of AuNPs was expressed as the number of AuNPs/mL, a higher degree of cytotoxicity was noted for the larger ̴50 nm AuNPs. To understand the influence of size, shape and capping, a systematic study design, in which only one of the variables changes, is determinant for correct data interpretation. Considering the results herein presented, for the sake of comparison of differently-sized AuNPs, it is preferable to design the study based upon the number of nanoparticles, since at a fixed Au concentration the number of particles available to promote effect is higher for smaller-sized AuNPs. Cellular internalization also differed among the tested AuNPs; although all were unable to cross the in vitro BBB, the intracellularly accumulated AuNPs can induce cell damage and later compromise BBB integrity and permeability.金纳米颗粒（Gold nanoparticles, AuNPs）在成像领域具备生物医学应用价值，而星形金纳米颗粒凭借优异的光学性能受到广泛关注。由于颗粒形状、尺寸及表面包覆层对其毒代动力学与毒效动力学具有显著影响，本研究以人脑微血管内皮细胞系（human Cerebral Microvascular Endothelial Cell line, hCMEC/D3）——一种体外血脑屏障（blood-brain barrier, BBB）模型——为研究对象，针对上述参数对细胞毒性、细胞摄取及体外通透性的影响开展了系统性多参数对比研究。研究团队合成了不同尺寸（14 nm与~50 nm）、不同形状（球形与星形）以及不同包覆剂（11-巯基十一烷酸或11-mercaptoundecanoic acid, MUA、柠檬酸钠）的金纳米颗粒，并对其进行了全面表征。受试金纳米颗粒的细胞毒性随作用时间与暴露浓度的变化趋势因颗粒种类而异。整体而言，星形金纳米颗粒的毒性高于球形金纳米颗粒；相较于11-巯基十一烷酸包覆的样品，柠檬酸钠包覆的金纳米颗粒毒性更强。关于尺寸的影响：当以相同金元素浓度进行对照时，尺寸更小的14 nm金纳米颗粒表现出更强的细胞毒性；但若以每毫升金纳米颗粒的数量作为浓度单位，则尺寸更大的~50 nm金纳米颗粒的细胞毒性更高。为准确厘清尺寸、形状与包覆层的独立影响，采用仅单一变量改变的系统性研究设计，是正确解读实验数据的核心前提。结合本研究所得结果，若需对不同尺寸的金纳米颗粒进行性能比较，建议以纳米颗粒总数为基准设计实验方案——因为在固定金元素浓度下，尺寸更小的金纳米颗粒的有效作用颗粒数更多。受试金纳米颗粒的细胞摄取能力同样存在差异；尽管所有样品均无法穿透体外血脑屏障，但胞内积累的金纳米颗粒可诱导细胞损伤，并最终损害血脑屏障的完整性与通透性。