Conjugation of Graphene Oxide with DNA-Modified Gold Nanoparticles to Develop a Novel Colorimetric Sensing Platform
Conjugation of Graphene Oxide with DNA-Modified Gold Nanoparticles to Develop a Novel Colorimetric Sensing Platform
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氧化石墨烯与 DNA 修饰的金纳米粒子结合开发新型比色传感平台
DOI：
10.1002/ppsc.201300200
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发表时间：
2014-02-01
影响因子：
2.7
通讯作者：
Li, Genxi
中科院分区：
文献类型：
--
作者：
Li, Chao;Yang, Yucai;Li, Genxi
氧化石墨烯（GO）是一种单原子厚的2D纳米材料，具有优异的电子，机械和热性能，[1，2]已经在生物分子识别事件中找到了关键位置。[3]自从Lu et al. [4a]由于GO是DNA和蛋白质分析的先驱，许多生物传感器已被开发，其中大多数是基于相同原理制造的荧光传感器。[5]即，GO可以结合并淬灭荧光团标记的单链DNA（ssDNA）探针，而在互补DNA（cDNA）存在下，由于双链体形成和随后的释放，荧光被恢复。这些研究使用荧光作为信号读出，因此它们需要昂贵的标记过程和相当复杂的荧光计。为了充分扩大GO用于简单的现场护理（POC）诊断技术，新的概念进展是非常需要探索。[6]另一方面，金纳米粒子（AuNP）作为另一种广泛使用的纳米材料，由于其迷人的光学性质和有前途的应用，也被用于生物传感器的构建。[7]具有固有的强表面等离子体共振吸收和高消光系数，使金纳米粒子成为理想的材料，以监测分析目标与低成本的便携式仪器，甚至用肉眼。例如，在这个实验室中，我们设计了一系列基于AuNP的比色传感器，用于检测各种物质，包括核酸，金属离子，小生物分子和蛋白质。[8]在这里，我们提出耦合金纳米颗粒和GO，这两种优良的纳米材料的固有特性，开发一个比色传感平台。该平台可用于分析大范围的目标，如DNA、小分子和金属离子。构建该平台的策略的原理是利用先前的报道，ssDNA而不是双链DNA（dsDNA）可能对GO具有特殊的吸附能力，[3]因此我们有理由相信，大量ssDNA修饰的AuNPs（ssDNA-AuNP）可以吸附到GO表面上并导致最终形成软络合物，这是由于球形ssDNA-AuNP对GO的交联作用。如果引入dsDNA，则随后的dsDNA修饰的AuNP（dsDNA-AuNP）不能充当GO的不同层之间的桥以缀合分散的GO和AuNP。因此，我们发现GO可以完全沉淀ssDNA-AuNP，而这种聚集不能用dsDNA或其他折叠良好的结构修饰的AuNP观察到。因此，可以使用GO滴定后上清液中残留的ssDNA-AuNP实现目标物种的比色检测。结合GO和AuNPs的优点，开发的生物传感器简单，灵敏，特异性用于检测不同的目标，这也允许用肉眼检测。基于颜色的信号读出不需要任何先进仪器的帮助，并且所制造的生物传感器使用稳定且具有成本效益的试剂，使得这种方法特别适用于POC检测。据我们所知，这是ssDNA-AuNP首次被用作交联GO的“胶水”，其也可以被开发为用于检测大范围靶标的新型比色传感平台。图1显示了通过透射电子显微镜（TEM）和原子力显微镜（AFM）表征的GO、AuNP、GO+ AuNP和GO+ ssDNA-AuNP复合物的典型图像。从图1 c，e中可以观察到，如果GO与AuNP混合而不进行修饰，则AuNP将不会吸附到GO的表面上。
Graphene oxide (GO), a single-atom-thick and 2D nanomaterial with excellent electronic, mechanical, and thermal properties,[1, 2] has found its pivotal place in biomolecular recognition events.[3] Since Lu et al.[4a] pioneered the use of GO for DNA and protein analysis, many biosensors have been exploited, most of which are fluorescence sensors fabricated with the same principle.[5] Namely, GO could bind and quench a fluorophore-labeled single-stranded DNA (ssDNA) probe, while in the presence of complementary DNA (cDNA), the fluorescence was recovered due to a duplex formation and subsequent release. These studies use fluorescence as the signal readout, so they require costly label process and fairly complex fluorometer. In order to adequately expand GO use for simple pointof-care (POC) diagnostic technique, new conceptual advances are highly required to exploration.[6] On the other hand, Au–nanoparticles (AuNP), which are another widely used nanomaterial, have also been used in biosensor construction due to the fascinating optical properties and promising applications.[7] Possessing intrinsically strong surface-plasmon resonance absorption and high extinction coefficients makes AuNPs an ideal material to monitor the analytical targets with low-cost portable instruments or even with naked eyes. For example, in this laboratory, we have designed a collection of AuNPs-based colorimetric sensors for the assay of various species including nucleic acid, metal ion, small biomolecule, and protein.[8] Here, we propose to couple the inherent characteristic of AuNPs and GO, the two kinds of excellent nanomaterials, to develop a colorimetric sensing platform. This platform can be used for the analysis of a large range of targets, such as DNA, small molecules, and metal ions. The principle of the strategy to construct the platform is to make use of the previous report that ssDNA instead of double-stranded DNA (dsDNA) may have special adsorption capacity onto GO,[3] thus we have reason to believe that a mass of ssDNA-modified AuNPs (ssDNA–AuNPs) can be adsorbed onto GO surface and lead to final formation of soft complexation, which results from the cross-linking effect of spherical ssDNA–AuNPs on GO. If dsDNA is introduced, the subsequent dsDNA-modified AuNPs (dsDNA–AuNPs) cannot act as a bridge between different layers of GO to conjugate the dispersed GO and AuNPs. Therefore, we find that GO can precipitate ssDNA–AuNPs completely, while such aggregation cannot be observed with dsDNA or other well-folded structure-modified AuNPs. Consequently, colorimetric detection of the target species can be realized using residual ssDNA–AuNPs in the supernatant after GO titration. Combining the advantages of both GO and AuNPs, the developed biosensor is simple, sensitive, and specific for detecting of different targets, which also allows detection with the naked eye. The color-based signal readout does not require the aid of any advanced instrument and the fabricated biosensor uses stable and cost-effective reagents, making this approach particularly suitable for POC detection. To the best of our knowledge, this is the first time that ssDNA–AuNPs are used as “glue” to cross-link GO, which can also be developed as a novel colorimetric sensing platform for the detection of a large range of targets. Figure 1 shows the typical images of GO, AuNPs, GO+ AuNPs, and GO+ ssDNA–AuNPs complex characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). From Figure 1 c, e, it is observed that AuNPs will not adsorb onto the surface of GO, if GO is mixed with AuNPs without the modification of …