International Iberian Nanotechnology Laboratory, Braga 4715-330, Portugal.
Department of Electronics Engineering, Chang Gung University, Taoyuan 33302, Taiwan.
Nanotechnology. 2021 Feb 26;32(9):095503. doi: 10.1088/1361-6528/abcd62.
The impact of different gold nanoparticle (GNP) structures on plasmonic enhancement for DNA detection is investigated on a few-layer graphene (FLG) surface plasmon resonance (SPR) sensor. Two distinct structures of gold nano-urchins (GNu) and gold nanorods (GNr) were used to bind the uniquely designed single-stranded probe DNA (ssDNA) of Mycobacterium tuberculosis complex DNA. The two types of GNP-ssDNA mixture were adsorbed onto the FLG-coated SPR sensor through the π-π stacking force between the ssDNA and the graphene layer. In the presence of complementary single-stranded DNA, the hybridization process took place and gradually removed the probes from the graphene surface. From SPR sensor preparation, the annealing process of the Au layer of the SPR sensor effectively enhanced the FLG coverage leading to a higher load of the probe DNA onto the sensing interface. The FLG was shown to be effective in providing a larger surface area for biomolecular capture due to its roughness. Carried out in the DNA hybridization study with the SPR sensor, GNu, with its rough and spiky structures, significantly reinforced the overall DNA hybridization signal compared with GNr with smooth superficies, especially in capturing the probe DNA. The DNA hybridization detection assisted by GNu reached the femtomolar range limit of detection. An optical simulation validated the extreme plasmonic field enhancement at the tip of the GNu spicules. The overall integrated approach of the graphene-based SPR sensor and GNu-assisted DNA detection provided the proof-of-concept for the possibility of tuberculosis disease screening using a low-cost and portable system to be potentially applied in remote or third-world countries.
研究了不同金纳米粒子（GNP）结构对几类石墨烯（FLG）表面等离子体共振（SPR）传感器上 DNA 检测的等离子体增强的影响。使用两种不同结构的金纳米刺（GNu）和金纳米棒（GNr）来结合结核分枝杆菌复合 DNA 的独特设计的单链探针 DNA（ssDNA）。这两种类型的 GNP-ssDNA 混合物通过 ssDNA 和石墨烯层之间的π-π堆积力被吸附到 FLG 涂覆的 SPR 传感器上。在互补单链 DNA 的存在下，杂交过程发生并逐渐将探针从石墨烯表面去除。从 SPR 传感器制备开始，SPR 传感器的 Au 层退火过程有效地增强了 FLG 的覆盖度，从而在传感界面上负载更多的探针 DNA。FLG 由于其粗糙度，在提供用于生物分子捕获的更大表面积方面是有效的。在 SPR 传感器的 DNA 杂交研究中，GNu 因其粗糙和多刺的结构，与表面光滑的 GNr 相比，显著增强了整体 DNA 杂交信号，特别是在捕获探针 DNA 方面。在 GNu 辅助的 DNA 检测中，DNA 杂交检测达到了飞摩尔检测限。光学模拟验证了 GNu 刺突尖端的极端等离子体场增强。基于石墨烯的 SPR 传感器和 GNu 辅助 DNA 检测的整体综合方法为使用低成本和便携式系统进行结核病筛查提供了概念验证，该系统有可能在偏远或第三世界国家中得到应用。
