Abstract：
Flexibility of nanomaterials is challenging but worthy to tune for biomedical applications. Biocompatible silica nanomaterials are under extensive exploration but are rarely observed to exhibit flexibility despite the polymeric nature. Herein, a facile one-step route is reported to ultrathin flexible silica nanosheets (NSs), whose low thickness and high diameter-to-thickness ratio enables folding. Thickness and diameter can be readily tuned to enable controlled flexibility. Mechanism study reveals that beyond the commonly used surfactant, the \"uncommon\" one bearing two hydrophobic tails play a guiding role in producing sheeted/layered/shelled structures, while addition of ethanol appropriately relieved the strong interfacial tension of the assembled surfactants, which will otherwise produce large curled sheeted structures. With these ultrathin NSs, it is further shown that the cellular preference for particle shape and rigidity is highly dependent on surface chemistry of nanoparticles: under high particle-cell affinity, NSs, and especially the flexible ones will be preferred by mammalian cells for internalization or attachment, while this preference is basically invalid when the affinity is low. Therefore, properties of the ultrathin silica NSs can be effectively expanded and empowered by surface chemistry to realize improved bio-sensing or drug delivery.
摘要：
纳米材料的灵活性具有挑战性，但值得针对生物医学应用进行调整。生物相容性二氧化硅纳米材料正在进行广泛的探索，但尽管具有聚合物性质，但很少观察到表现出柔韧性。在这里，据报道，超薄柔性二氧化硅纳米片(NS)是一种简单的一步法路线，其低厚度和高直径厚度比使折叠。可以容易地调节厚度和直径以实现受控的柔性。机理研究表明，除了常用的表面活性剂，带有两个疏水尾巴的“不常见”在生产片状/层状/带壳结构中起指导作用，而乙醇的添加适当地减轻了组装的表面活性剂的强界面张力，否则会产生大卷曲的片状结构。有了这些超薄NS，进一步表明，细胞对颗粒形状和刚性的偏好高度依赖于纳米颗粒的表面化学：在高颗粒细胞亲和力下，NS,尤其是柔性的将被哺乳动物细胞优选用于内化或附着，而当亲和力较低时，此首选项基本上是无效的。因此,超薄二氧化硅NSs的性能可以通过表面化学有效地扩展和增强，以实现改进的生物传感或药物递送。
