Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
J Am Chem Soc. 2011 Mar 2;133(8):2664-71. doi: 10.1021/ja109561e. Epub 2011 Feb 4.
A common problem in detecting metal ions with fluorescentchemosensors is the emission-suppressing effects of fluorescence-quenching metal ions. This quenching tendency makes it difficult to design sensors with turn-on signal, and differentiate between several metal ions that may yield a strong quenching response. To address these challenges, we investigate a new sensor design strategy, incorporating fluorophores and metal ligands as DNA base replacements in DNA-like oligomers, for generating a broader range of responses for quenching metal ions. The modular molecular design enabled rapid synthesis and discovery of sensors from libraries on PEG-polystyrene beads. Using this approach, water-soluble sensors 1-5 were identified as strong responders to a set of eight typically quenching metal ions (Co(2+), Ni(2+), Cu(2+), Hg(2+), Pb(2+), Ag(+), Cr(3+), and Fe(3+)). They were synthesized and characterized for sensing responses in solution. Cross-screening with the full set of metal ions showed that they have a wide variety of responses, including emission enhancements and red- and blue-shifts. The diversity of sensor responses allows as few as two sensors (1 and 2) to be used together to successfully differentiate these eight metals. As a test, a set of unknown metal ion solutions in blind studies were also successfully identified based on the response pattern of the sensors. The modular nature of the sensor design strategy suggests a broadly applicable approach to finding sensors for differentiating many different cations by pattern-based recognition, simply by varying the sequence and composition of ligands and fluorophores on a DNA synthesizer.
在使用荧光化学传感器检测金属离子时，一个常见的问题是荧光猝灭金属离子的发射抑制效应。这种猝灭趋势使得设计具有开启信号的传感器变得困难，并且难以区分可能产生强猝灭响应的几种金属离子。为了解决这些挑战，我们研究了一种新的传感器设计策略，即将荧光团和金属配体作为 DNA 类似物寡聚物中的 DNA 碱基替代物，以产生更广泛的响应范围，用于猝灭金属离子。模块化的分子设计使得能够从 PEG-聚苯乙烯珠上的文库中快速合成和发现传感器。使用这种方法，鉴定了水溶性传感器 1-5 对一组八种典型猝灭金属离子（Co(2+)、Ni(2+)、Cu(2+)、Hg(2+)、Pb(2+)、Ag(+)、Cr(3+)和 Fe(3+)）具有很强的响应。它们被合成并在溶液中进行了传感响应的表征。与全套金属离子的交叉筛选表明，它们具有广泛的响应，包括发射增强和红移和蓝移。传感器响应的多样性使得只需使用两个传感器（1 和 2）就可以成功区分这八种金属。作为测试，在盲研究中，还成功地根据传感器的响应模式识别了一组未知金属离子溶液。传感器设计策略的模块化性质表明，通过基于模式的识别来寻找区分许多不同阳离子的传感器是一种广泛适用的方法，只需在 DNA 合成器上改变配体和荧光团的序列和组成即可。
