University of Illinois at Chicago, Department of Bioengineering, United States of America.
Nanotechnology. 2017 Sep 15;28(37):375501. doi: 10.1088/1361-6528/aa7e50. Epub 2017 Jul 11.
In this article, we report a graphene oxide-based nanosensor incorporating semiconductor quantum dots linked to DNA-aptamers that functions as a 'turn-off' fluorescent nanosensor for detection of low concentrations of analytes. A specific demonstration of this turn-off aptasensor is presented for the case of the detection of mercury (II) ions. In this system, ensembles of aptamer-based quantum-dot sensors are anchored onto graphene oxide (GO) flakes which provide a platform for analyte detection in the vicinity of GO. Herein, the operation of this ensemble-based nanosensor is demonstrated for mercury ions, which upon addition of mercury, quenching of the emission intensity from the quantum dots is observed due to resonance energy transfer between quantum dots and the gold nanoparticle connected via a mercury target aptamer. A key result is that the usually dominant effect of quenching of the quantum dot due to close proximity to the GO can be reduced to negligible levels by using a linker molecule in conjunctions with the aptamer-based nanosensor. The effect of ionic concentration of the background matrix on the emission intensity was also investigated. The sensor system is found to be highly selective towards mercury and exhibits a linear behavior (r > 0.99) in the nanomolar concentration range. The detection limit of the sensor towards mercury with no GO present was found to be 16.5 nM. With GO attached to molecular beacon via 14 base, 35 base, and 51 base long linker DNA, the detection limit was found to be 38.4 nM, 9.45 nM, and 11.38 nM; respectively.
在本文中，我们报告了一种基于氧化石墨烯的纳米传感器，该传感器结合了与 DNA-适配体相连的半导体量子点，可作为用于检测低浓度分析物的“关闭”荧光纳米传感器。针对汞（II）离子的检测，具体展示了这种关闭型适体传感器。在该系统中，基于适配体的量子点传感器的集合被固定在氧化石墨烯（GO）薄片上，该薄片为 GO 附近的分析物检测提供了平台。在此，展示了该基于集合的纳米传感器的操作，对于汞离子，在添加汞后，由于通过与汞靶适体连接的金纳米粒子之间的共振能量转移，观察到来自量子点的发射强度猝灭。一个关键的结果是，通过使用与适体纳米传感器结合的连接分子，可以将由于接近 GO 而通常占主导地位的量子点猝灭效应降低到可忽略的水平。还研究了背景基质的离子浓度对发射强度的影响。该传感器系统对汞具有高度选择性，并在纳摩尔浓度范围内表现出线性行为（r> 0.99）。发现没有 GO 存在时传感器对汞的检测限为 16.5 nM。通过将 14 个碱基、35 个碱基和 51 个碱基长的连接 DNA 将 GO 连接到分子信标上，检测限分别为 38.4 nM、9.45 nM 和 11.38 nM。
