Bioengineering Department, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Department of Pediatrics, Center for Blood Oxygen Transport and Hemostasis, University of Maryland Baltimore School of Medicine, Health Sciences Research Facility III, 670 W Baltimore St., Baltimore, MD, 21201, USA.
Adv Sci (Weinh). 2022 Aug;9(22):e2202414. doi: 10.1002/advs.202202414. Epub 2022 Jun 3.
Small molecular NIR-II dyes are highly desirable for various biomedical applications. However, NIR-II probes are still limited due to the complex synthetic processes and inadequate availability of fluorescent core. Herein, the design and synthesis of three small molecular NIR-II dyes are reported. These dyes can be excited at 850-915 nm and emitted at 1280-1290 nm with a large stokes shift (≈375 nm). Experimental and computational results indicate a 2:1 preferable host-guest assembly between the cucurbit[8]uril (CB) and dye molecules. Interestingly, the dyes when self-assembled in presence of CB leads to the formation of nanocubes (≈200 nm) and exhibits marked enhancement in fluorescence emission intensity (Switch-On). However, the addition of red carbon dots (rCDots, ≈10 nm) quenches the fluorescence of these host-guest complexes (Switch-Off) providing flexibility in the user-defined tuning of photoluminescence. The turn-ON complex found to have comparable quantum yield to the commercially available near-infrared fluorophore, IR-26. The aqueous dispersibility, cellular and blood compatibility, and NIR-II bioimaging capability of the inclusion complexes is also explored. Thus, a switchable fluorescence behavior, driven by host-guest complexation and supramolecular self-assembly, is demonstrated here for three new NIR-II dyes.
小分子近红外二区染料在各种生物医学应用中非常理想。然而，由于合成工艺复杂和荧光核心的可用性不足，近红外二区探针仍然有限。本文报道了三种小分子近红外二区染料的设计和合成。这些染料可以在 850-915nm 处被激发，在 1280-1290nm 处发射，具有较大的斯托克斯位移（≈375nm）。实验和计算结果表明，葫芦[8]脲（CB）和染料分子之间存在 2:1 的优先主客体组装。有趣的是，当染料在 CB 的存在下自组装时，会形成纳米立方体形貌（≈200nm），并表现出显著增强的荧光发射强度（开启）。然而，添加红色碳点（rCDots，≈10nm）会猝灭这些主客体配合物的荧光（关闭），从而为用户定义的光致发光调谐提供了灵活性。所发现的开启复合物具有与市售近红外荧光团 IR-26 相当的量子产率。还探索了包合物的水分散性、细胞和血液相容性以及近红外二区生物成像能力。因此，本文展示了三种新的近红外二区染料通过主客体络合和超分子自组装驱动的可切换荧光行为。
