AbstractA composite consisting of NiCo2S4 and reduced graphene oxide (rGO) was prepared via a hydrothermal process. Compared to individual NiCo2S4 nanomaterials or reduced graphene oxide, the composite exhibits enhanced oxidase-like activity. It is found that dopamine (DA) inhibits the ability of NiCo2S4-rGO to oxidize the substrate 3,3′,5′,5′-tetramethylbenzidine (TMB) to form blue colored ox-TMB. Based on these findings, a colorimetric method for determination of DA was worked out. The absorption, best measured at 652 nm, increases linearly in the 0.5–100 μM DA concentration range, and the limit of detection is 0.42 μM. This method was successfully applied to the detection of DA in spiked human serum samples. Graphical abstractA hierarchical NiCo2S4-rGO composite was prepared through two-step hydrothermal process. It exhibits enhanced oxidase-like activity which, however, is inhibited by dopamine (DA). Hence, less blue colored ox-TMB is formed by oxidation of 3,3′,5,5′-tetramethylbenzidine in the presence of dopamine.

中文翻译：

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利用分层NiCo2S4-rGO复合材料增强的氧化酶模拟活性比色测定多巴胺

摘要 通过水热法制备了由 NiCo2S4 和还原氧化石墨烯 (rGO) 组成的复合材料。与单独的 NiCo2S4 纳米材料或还原氧化石墨烯相比，该复合材料表现出增强的氧化酶样活性。发现多巴胺 (DA) 抑制 NiCo2S4-rGO 氧化底物 3,3',5',5'-四甲基联苯胺 (TMB) 形成蓝色 ox-TMB 的能力。基于这些发现，制定了测定 DA 的比色法。吸收最好在 652 nm 处测量，在 0.5–100 μM DA 浓度范围内线性增加，检测限为 0.42 μM。该方法成功应用于加标人血清样品中DA的检测。图形摘要通过两步水热法制备了分层的 NiCo2S4-rGO 复合材料。它表现出增强的氧化酶样活性，但被多巴胺 (DA) 抑制。因此，在多巴胺存在下氧化 3,3',5,5'-四甲基联苯胺形成较少蓝色的 ox-TMB。