Massey Melissa, Medintz Igor L, Ancona Mario G, Algar W Russ
Department of Chemistry, University of British Columbia , 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.
ACS Sens. 2017 Aug 25;2(8):1205-1214. doi: 10.1021/acssensors.7b00355. Epub 2017 Aug 8.
Molecular logic devices (MLDs) constructed from DNA are promising for applications in bioanalysis, computing, and other applications requiring Boolean logic. These MLDs accept oligonucleotide inputs and generate fluorescence output through changes in structure. Although fluorescent dyes are most common in MLD designs, nontraditional luminescent materials with unique optical properties can potentially enhance MLD capabilities. In this context, luminescent lanthanide complexes (LLCs) have been largely overlooked. Here, we demonstrate a set of high-contrast DNA photonic logic gates based on toehold-mediated strand displacement and time-gated FRET. The gates include NAND, NOR, OR, and AND designs that accept two unlabeled target oligonucleotide sequences as inputs. Bright "true" output states utilize time-gated, FRET-sensitized emission from an Alexa Fluor 546 (A546) dye acceptor paired with a luminescent terbium cryptate (Tb) donor. Dark "false" output states are generated through either displacement of the A546, or through competitive and sequential quenching of the Tb or A546 by a dark quencher. Time-gated FRET and the long luminescence lifetime and spectrally narrow emission lines of the Tb donor enable 4-10-fold contrast between Boolean outputs, ≤10% signal variation for a common output, multicolor implementation of two logic gates in parallel, and effective performance in buffer and serum. These metrics exceed those reported for many other logic gate designs with only fluorescent dyes and with other non-LLC materials. Preliminary three-input AND and NAND gates are also demonstrated. The powerful combination of an LLC FRET donor with DNA-based logic gates is anticipated to have many future applications in bioanalysis.
由DNA构建的分子逻辑器件（MLD）在生物分析、计算以及其他需要布尔逻辑的应用领域具有广阔的应用前景。这些MLD接受寡核苷酸输入，并通过结构变化产生荧光输出。尽管荧光染料在MLD设计中最为常见，但具有独特光学性质的非传统发光材料有可能增强MLD的性能。在这种背景下，发光镧系配合物（LLC）在很大程度上被忽视了。在此，我们展示了一组基于 toehold介导的链置换和时间门控荧光共振能量转移（FRET）的高对比度DNA光子逻辑门。这些逻辑门包括与非标记的靶寡核苷酸序列作为输入的与非、或非、或和与设计。明亮的“真”输出状态利用与发光铽穴状配合物（Tb）供体配对的Alexa Fluor 546（A546）染料受体的时间门控、FRET敏化发射。暗的“假”输出状态是通过A546的置换，或通过暗猝灭剂对Tb或A546的竞争性和顺序猝灭产生的。时间门控FRET以及Tb供体的长发光寿命和光谱窄发射线使得布尔输出之间的对比度达到4至10倍，常见输出的信号变化≤10%，两个逻辑门的多色并行实现，以及在缓冲液和血清中的有效性能。这些指标超过了许多仅使用荧光染料和其他非LLC材料的其他逻辑门设计所报道的指标。还展示了初步的三输入与和与非门。LLC FRET供体与基于DNA的逻辑门的强大组合预计在生物分析中有许多未来应用。
