Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, DC 20375, USA.
J Am Chem Soc. 2010 Dec 29;132(51):18177-90. doi: 10.1021/ja106465x. Epub 2010 Dec 8.
Combining the inherent scaffolding provided by DNA structure with spatial control over fluorophore positioning allows the creation of DNA-based photonic wires with the capacity to transfer excitation energy over distances greater than 150 Å. We demonstrate hybrid multifluorophore DNA-photonic wires that both self-assemble around semiconductor quantum dots (QDs) and exploit their unique photophysical properties. In this architecture, the QDs function as both central nanoscaffolds and ultraviolet energy harvesting donors that drive Förster resonance energy transfer (FRET) cascades through the DNA wires with emissions that approach the near-infrared. To assemble the wires, DNA fragments labeled with a series of increasingly red-shifted acceptor-dyes were hybridized in a predetermined linear arrangement to a complementary DNA template that was chemoselectively modified with a hexahistidine-appended peptide. The peptide portion facilitated metal-affinity coordination of multiple hybridized DNA-dye structures to a central QD completing the final nanocrystal-DNA photonic wire structure. We assembled several such hybrid structures where labeled-acceptor dyes were excited by the QDs and arranged to interact with each other via consecutive FRET processes. The inherently facile reconfiguration properties of this design allowed testing of alternate formats including the addition of an intercalating dye located in the template DNA or placement of multiple identical dye acceptors that engaged in homoFRET. Lastly, a photonic structure linking the central QD with multiple copies of DNA hybridized with 4-sequentially arranged acceptor dyes and demonstrating 4-consecutive energy transfer steps was examined. Step-by-step monitoring of energy transfer with both steady-state and time-resolved spectroscopy allowed efficiencies to be tracked through the structures and suggested that acceptor dye quantum yields are the predominant limiting factor. Integrating such DNA-based photonic structures with QDs can help create a new generation of biophotonic wire assemblies with widespread potential in nanotechnology.
将 DNA 结构固有的支架与荧光团定位的空间控制相结合，可构建能够在超过 150Å 的距离上传递激发能的基于 DNA 的光子线。我们展示了既能自组装在半导体量子点 (QD) 周围又能利用其独特的光物理性质的混合多荧光团 DNA-光子线。在这种结构中，QD 既充当中心纳米支架，又充当紫外能量收集供体，通过 DNA 线驱动福斯特共振能量转移 (FRET) 级联，其发射接近近红外。为了组装这些线，用一系列逐渐红移的受体染料标记的 DNA 片段以预定的线性排列杂交到互补的 DNA 模板上，该模板通过化学选择性修饰带有六组氨酸附加肽的方式进行修饰。肽部分促进了多个杂交 DNA-染料结构与中心 QD 的金属亲和力配位，完成了最终的纳米晶-DNA 光子线结构。我们组装了几个这样的混合结构，其中标记的受体染料被 QD 激发，并通过连续的 FRET 过程排列相互作用。该设计固有的易于重构特性允许测试替代格式，包括在模板 DNA 中添加一个嵌入染料，或放置多个参与同分子 FRET 的相同染料受体。最后，检查了一个将中心 QD 与多个用 4 个顺序排列的受体染料杂交的 DNA 分子连接起来的光子结构，并证明了 4 个连续的能量转移步骤。通过稳态和时间分辨光谱对能量转移进行逐步监测，可跟踪效率通过结构，并表明受体染料量子产率是主要的限制因素。将这种基于 DNA 的光子结构与 QD 集成可以帮助创建新一代具有广泛应用潜力的生物光子线组件。
