Highly sensitive and selective colorimetric sensors for uranyl (UO2(2+)): development and comparison of labeled and label-free DNAzyme-gold nanoparticle systems.
Highly sensitive and selective colorimetric sensors for uranyl (UO2(2+)): development and comparison of labeled and label-free DNAzyme-gold nanoparticle systems.
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DOI：
10.1021/ja803607z
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发表时间：
2008-10-29
影响因子：
15
通讯作者：
Lu, Yi
中科院分区：
文献类型：
--
作者：
Lee, Jung Heon;Wang, Zidong;Liu, Juewen;Lu, Yi
基于铀酰（UO 22+）特异性DNA酶和金纳米颗粒（AuNP）的比色铀传感器已经开发并使用标记和无标记方法进行了验证。在标记的方法中，铀酰特异性DNA酶连接到AuNP，形成紫色聚集体。铀酰的存在诱导DNA酶功能化的AuNP聚集体的分解，产生红色的单个AuNP。一旦组装，这种“开启”传感器是高度稳定的，并且在室温下在单个步骤中工作，并且在30分钟的反应时间后具有50 nM的检测限。另一方面，无标记方法利用了单链和双链DNA在AuNP上的不同吸附性质，这影响了AuNP在NaCl存在下的稳定性。铀酰的存在导致DNA酶切割底物，释放出可以吸附在AuNP上并保护它们免于聚集的单链DNA。利用这一现象，开发了一种“关断”传感器，该传感器易于通过反应淬灭来控制，并且在室温下反应6分钟后具有1 nM的检测限。这两种传感器对其他金属离子都有很好的选择性，检测限低于美国环境保护署（EPA）规定的饮用水中UO22+的最大污染水平130 nM。该研究代表了使用相同DNAzyme和AuNP的这两种类型的传感器方法的第一次直接系统比较，从而可以揭示每种方法的优点，缺点，通用性，局限性和潜在应用。所得结果不仅为铀酰的实际传感应用提供了依据，而且对其他目标的比色传感器的设计也具有指导意义。
Colorimetric uranium sensors based on uranyl (UO22+) specific DNAzyme and gold nanoparticles (AuNP) have been developed and demonstrated using both labeled and label-free methods. In the labeled method, a uranyl-specific DNAzyme was attached to AuNP, forming purple aggregates. The presence of uranyl induced disassembly of the DNAzyme functionalized AuNP aggregates, resulting in red individual AuNPs. Once assembled, such a “turn-on” sensor is highly stable and worked in a single step at room temperature and had detection limit of 50 nM after 30 min. of reaction time. The label-free method, on the other hand, utilizes the different adsorption properties of single stranded and double stranded DNA on AuNPs, which affects the stability of AuNPs in the presence of NaCl. The presence of uranyl resulted in cleavage of substrate by DNAzyme, releasing a single stranded DNA that can be adsorbed on AuNPs and protect them from aggregation. Taking advantage of this phenomenon, a “turn-off” sensor was developed, which is easy to control through reaction quenching, and has 1 nM detection limit after 6 min. of reaction at room temperature. Both sensors have excellent selectivity over other metal ions and have detection limits below the maximum contamination level of 130 nM for UO22+ in drinking water defined by the US Environmental Protection Agency (EPA). The study represents the first direct systematic comparison of these two types of sensor methods using the same DNAzyme and AuNPs, making it possible to reveal advantages, disadvantages, versatility, and limitations and potential applications of each method. The results obtained not only allow practical sensing application for uranyl, but also serve as a guide for choosing different method for designing colorimetric sensors for other targets.
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