A silver cluster-DNA equilibrium.
A silver cluster-DNA equilibrium.
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DOI：
10.1021/ac4028559
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发表时间：
2013-10-15
影响因子：
7.4
通讯作者：
McMullan DR
中科院分区：
文献类型：
--
作者：
Petty JT;Sergev OO;Nicholson DA;Goodwin PM;Giri B;McMullan DR
DNA封装了银簇，这些混合纳米材料形成了分子传感器。我们讨论了具有四个特性的银簇-寡核苷酸传感器。首先，在单链DNA内形成特定的报告簇。该模板使用具有互补寡核苷酸的不同3'识别位点的5'簇结构域CCCCAACTCCTT。模块化复合材料股排他地形成λmax = 400 nm且具有低发射的簇。共轭物进行色谱纯化，其元素分析测量簇加合物与~11银原子。第二，杂交改变了集群。尺寸排阻色谱显示单链缀合物的3'识别位点与其互补物杂交。这种二级结构变化使簇吸收从400 nm移动到490 nm，并在550 nm处产生发射。第三，集群规模保持不变。像它们的紫色前辈一样，纯化的蓝绿色簇有~11个银原子。通过从蓝绿色缀合物中提取补体并逆转光谱变化进一步支持簇完整性。第四，集群转型是一种均衡。互补链产生等吸光点，因此直接连接紫色簇的单链宿主和蓝绿色簇的杂交类似物。这种平衡随温度而变化。范特霍夫分析表明，更长和更稳定的双链体有利于蓝绿色簇。然而，杂交的簇宿主比它们的天然DNA对应物更不稳定，并且当短互补物暴露S1-S2内的核碱基时，稳定性进一步降低。双链体不稳定性表明，未配对的核碱基协调紫色簇，有利于单链传感器。先天杂交和外源折叠之间的平衡突出了用于感测的银簇的独特特征-它们既是发色报告物又是调节分析物-传感器相互作用的配体。
DNA encapsulates silver clusters, and these hybrid nanomaterials form molecular sensors. We discuss a silver cluster-oligonucleotide sensor with four characteristics. First, a specific reporting cluster forms within a single-stranded DNA. This template uses the 5’ cluster domain CCCCAACTCCTT with different 3’ recognition sites for complementary oligonucleotides. The modular composite strand exclusively forms a cluster with λmax = 400 nm and with low emission. Conjugates were chromatographically purified, and their elemental analysis measured a cluster adduct with ~11 silver atoms. Second, hybridization transforms the cluster. Size exclusion chromatography shows that the 3’ recognition sites of the single-stranded conjugates hybridize with their complements. This secondary structural change both shifts cluster absorption from 400 to 490 nm and develops emission at 550 nm. Third, cluster size remains intact. Like their violet predecessors, purified blue-green clusters have ~11 silver atoms. Cluster integrity is further supported by extracting the complement from the blue-green conjugate and reversing the spectral changes. Fourth, the cluster transformation is an equilibrium. Complementary strands generate an isosbestic point and thus directly link single-stranded hosts for the violet cluster and their hybridized analogs for the blue-green cluster. This equilibrium shifts with temperature. A van’t Hoff analysis shows that longer and more stable duplexes favor the blue-green cluster. However, hybridized cluster hosts are less stable than their native DNA counterparts, and stability further degrades when short complements expose nucleobases within S1-S2. Duplex instability suggests that unpaired nucleobases coordinate the violet cluster and favor the single-stranded sensor. A balance between innate hybridization and exogenous folding highlights a distinct feature of silver clusters for sensing – they are both chromophoric reporters and ligands that modulate analyte-sensor interactions.