Bogh Sidsel Ammitzbøll, Cerretani Cecilia, Kacenauskaite Laura, Carro-Temboury Miguel R, Vosch Tom
Nanoscience Center and Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.
ACS Omega. 2017 Aug 17;2(8):4657-4664. doi: 10.1021/acsomega.7b00582. eCollection 2017 Aug 31.
A single-stranded DNA-based (ssDNA) dyad was constructed comprising 15 silver atoms stabilized by a ssDNA scaffold (DNA-AgNC) and an Alexa 546 fluorophore bound to the 5' end. The Alexa 546 was chosen to function as a Förster resonance energy transfer (FRET) donor for the AgNC. Time-correlated single photon counting (TCSPC) experiments allowed unraveling the excited-state relaxation processes of the purified DNA-AgNC-only system. The TCSPC results revealed slow relaxation dynamics and a red shift of the emission spectrum during the excited-state lifetime. The results from the model systems were needed to understand the more complicated decay pathways present in the collected high-performance liquid chromatography fraction, which contained the dyad (37% of the emissive population). In the dyad system, the FRET efficiency between donor and acceptor was determined to be 94% using TCSPC, yielding a center-to-center distance of 4.6 nm. To date, only limited structural information on DNA-AgNCs is available and the use of TCSPC and FRET can provide information on the center-to-center distance between chromophores and provide positional information in nanostructures composed of AgNCs.
构建了一种基于单链DNA（ssDNA）的二元体系，其由15个通过ssDNA支架稳定的银原子（DNA-AgNC）和一个与5'端结合的Alexa 546荧光团组成。选择Alexa 546作为AgNC的Förster共振能量转移（FRET）供体。时间相关单光子计数（TCSPC）实验有助于揭示仅纯化的DNA-AgNC体系的激发态弛豫过程。TCSPC结果显示，在激发态寿命期间，弛豫动力学缓慢且发射光谱发生红移。需要模型系统的结果来理解收集的高效液相色谱馏分中存在的更复杂的衰变途径，该馏分包含二元体系（发射群体的37%）。在二元体系中，使用TCSPC测定供体和受体之间的FRET效率为94%，中心到中心距离为4.6 nm。迄今为止，关于DNA-AgNCs的结构信息有限，而TCSPC和FRET的使用可以提供发色团之间中心到中心距离的信息，并在由AgNCs组成的纳米结构中提供位置信息。
