Department of Chemistry, Stanford University , Stanford, California 94305, United States.
J Am Chem Soc. 2017 Sep 20;139(37):13147-13155. doi: 10.1021/jacs.7b07420. Epub 2017 Sep 12.
Nanometer-sized fragments of carbon in the form of multilayer graphene ("carbon dots") have been under highly active study for applications in imaging. While offering advantages of low toxicity and photostability, such nanomaterials are inhomogeneous and have limited wavelengths of emission. Here we address these issues by assembling luminescent aromatic C16-C38 hydrocarbons together on a DNA scaffold in homogeneous, soluble molecular compounds. Monomer deoxyribosides of five different aromatic hydrocarbons were synthesized and assembled into a library of 1296 different tetramer compounds on PEG-polystyrene beads. These were screened for photostability and a range of emission colors using 365 nm excitation, observing visible light (>400 nm) emission. We identified a set of six oligomers (DNA-carbon assemblies, DNA-CAs) with exceptional photostability that emit from 400 to 680 nm in water, with Stokes shifts of up to 110 nm, quantum yields ranging from 0.01 to 0.29, and fluorescence lifetimes from 3 to 42 ns. In addition, several of these DNA-CAs exhibited white emission in aqueous solution. The molecules were used in multispectral cell imaging experiments and were taken up into cells passively. The results expand the range of emission properties that can be achieved in water with all-hydrocarbon chromophores and establish the use of the DNA scaffold to arrange carbon layers in homogeneous, rapidly synthesized assemblies.
纳米级的多层石墨烯形式的碳碎片（“碳点”）在成像应用中受到了高度关注。虽然这种纳米材料具有低毒性和光稳定性的优点，但它们是不均匀的，发射波长有限。在这里，我们通过将发光芳香族 C16-C38 烃组装在 DNA 支架上，解决了这些问题，形成了均匀、可溶性的分子化合物。合成了五种不同芳香烃的单体脱氧核糖核苷酸，并将其组装成 1296 种不同的四聚体化合物库，在 PEG-聚苯乙烯珠上。使用 365nm 激发，对这些化合物进行了光稳定性和一系列发射颜色的筛选，观察到可见光（>400nm）发射。我们鉴定了一组具有卓越光稳定性的六种低聚物（DNA-碳组装体，DNA-CA），它们在水中从 400nm 到 680nm 发射，Stokes 位移高达 110nm，量子产率范围从 0.01 到 0.29，荧光寿命从 3ns 到 42ns。此外，这些 DNA-CA 中的几种在水溶液中表现出白色发射。这些分子被用于多谱细胞成像实验，并被被动地摄取到细胞中。研究结果扩展了使用全碳生色团在水中实现发射特性的范围，并确立了使用 DNA 支架在均匀、快速合成的组装体中排列碳层的用途。
