Settele Simon, Stammer Florian, Sebastian Finn L, Lindenthal Sebastian, Wald Simon R, Li Han, Flavel Benjamin S, Zaumseil Jana
Institute for Physical Chemistry, Universität Heidelberg, D-69120 Heidelberg, Germany.
Department of Mechanical and Materials Engineering, University of Turku, FI-20014 Turku, Finland.
ACS Nano. 2024 Jul 25;18(31):20667-78. doi: 10.1021/acsnano.4c06448.
The covalent functionalization of single-walled carbon nanotubes (SWNTs) with luminescent oxygen defects increases their brightness and enables their application as optical biosensors or fluorescent probes for in vivo imaging in the second-biological window (NIR-II). However, obtaining luminescent defects with high brightness is challenging with the current functionalization methods due to a restricted window of reaction conditions or the necessity for controlled irradiation with ultraviolet light. Here, we report a method for introducing luminescent oxygen defects via a Fenton-like reaction that uses benign and inexpensive chemicals without light irradiation. (6,5) SWNTs in aqueous dispersion functionalized with this method show bright E* emission (1105 nm) with 3.2 times higher peak intensities than the pristine E emission and a reproducible photoluminescence quantum yield of 3%. The functionalization can be performed within a wide range of reaction parameters and even with unsorted nanotube raw material at high concentrations (100 mg L), giving access to large amounts of brightly luminescent SWNTs. We further find that the introduced oxygen defects rearrange under light irradiation, which gives additional insights into the structure and dynamics of oxygen defects. Finally, the functionalization of ultrashort SWNTs with oxygen defects also enables high photoluminescence quantum yields. Their excellent emission properties are retained after surfactant exchange with biocompatible pegylated phospholipids or single-stranded DNA to make them suitable for in vivo NIR-II imaging and dopamine sensing.
具有发光氧缺陷的单壁碳纳米管（SWNTs）的共价功能化提高了它们的亮度，并使其能够作为光学生物传感器或荧光探针用于第二生物窗口（近红外二区，NIR-II）的体内成像。然而，由于反应条件的窗口受限或需要用紫外光进行可控照射，目前的功能化方法难以获得高亮度的发光缺陷。在此，我们报道了一种通过类芬顿反应引入发光氧缺陷的方法，该方法使用良性且廉价的化学物质，无需光照。用这种方法功能化的水分散体中的（6,5）SWNTs显示出明亮的E*发射（1105 nm），其峰值强度比原始E发射高3.2倍，且光致发光量子产率可重复，为3%。该功能化可以在广泛的反应参数范围内进行，甚至可以使用高浓度（100 mg/L）的未分类纳米管原料，从而获得大量明亮发光的SWNTs。我们进一步发现，引入的氧缺陷在光照下会重新排列，这为氧缺陷的结构和动力学提供了更多见解。最后，具有氧缺陷的超短SWNTs的功能化也能实现高光致发光量子产率。在用生物相容性聚乙二醇化磷脂或单链DNA进行表面活性剂交换后，它们优异的发射特性得以保留，使其适用于体内近红外二区成像和多巴胺传感。
