An integrated electrochemical sensing platform is presented, in which stable graphene nanosheets are entrapped within hierarchical gold nano/micro islands (NMI) for the selective detection of dopamine. The fabrication method, which combines lithography, electrodeposition and liquid exfoliation, results in a microscale fluidic reactor capable of handling small volumes (10 μl) of sample. This configuration has advantageous properties, including enhanced sensitivity towards current responses from redox reaction of dopamine to dopamine orthoquinone. The NMIs‘spatial orientation inhibits the agglomeration of graphene, while their nanostructured interface enhances adhesion to graphene nanosheets. In turn, this leads to an enlarged surface and to an accumulation of free electrons on the electrode surface. The superior electrocatalytic activity for dopamine is attributed to the high density of π-electrons on graphene nanosheets. In addition, the selectivity of the assay in the presence of other interferents is assumed to be a result of the sp 2 π-interactions between the negatively charged graphene layer and the aromatic rings of dopamine. At a working potential of 0.15 V vs Ag/AgCl, the assay has a detection limit of 1.13 nM, a linear range of 1 nM- 100 μM, and apparent recoveries of 106% in spiked synthetic urine. Graphical abstract Schematic presentation of an integrated electrochemical sensing platform, in which stable graphene nanosheets are entrapped within hierarchical gold nano/micro islands (NMI) for selective detection of dopamine. Platinum (Pt) wire and Silver/Silver-Chloride (Ag/AgCl) were used as counter and reference electrode, respectively.

中文翻译：

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嵌入石墨烯/分级金纳米结构的微型反应器用于电化学传感：在多巴胺测定中的应用

提出了一种集成的电化学传感平台，其中稳定的石墨烯纳米片被包裹在分级金纳米/微岛 (NMI) 中，用于选择性检测多巴胺。该制造方法结合了光刻、电沉积和液体剥离，产生了能够处理小体积 (10 μl) 样品的微型流体反应器。这种配置具有有利的特性，包括对多巴胺氧化还原反应生成多巴胺邻醌的电流响应增强的敏感性。NMI 的空间取向抑制了石墨烯的团聚，而它们的纳米结构界面增强了对石墨烯纳米片的附着力。反过来，这会导致扩大的表面和自由电子在电极表面上的积累。多巴胺优异的电催化活性归因于石墨烯纳米片上的高密度 π 电子。此外，假设在其他干扰物存在下测定的选择性是带负电荷的石墨烯层与多巴胺的芳环之间的 sp 2 π-相互作用的结果。在 0.15 V 与 Ag/AgCl 的工作电位下，该测定的检测限为 1.13 nM，线性范围为 1 nM-100 μM，在加标合成尿中的表观回收率为 106%。图形摘要 集成电化学传感平台的示意图，其中稳定的石墨烯纳米片被包裹在分级金纳米/微岛 (NMI) 中，用于选择性检测多巴胺。铂 (Pt) 线和银/氯化银 (Ag/AgCl) 用作对电极和参比电极，