AbstractThe authors describe a method for synthesizing graphene oxide quantum dots (GOQDs) possessing orange fluorescence with emission wavelength that can be tuned over the range from 537 to 593 nm by variation of the excitation wavelength. The GOQD display peroxidase-mimicking catalytic activity. Specifically, they catalyze the oxidation of dopamine to produce 4-(2-aminoethyl)benzene-1,2-quinone (AQ) which is colored and can quench the fluorescence of GOQDs. However, quenching is reversed by addition of NADP+, but not by its reduced form (NADPH). Based on these findings, an assay was worked out to monitor enzymatic reactions involving NADP+. The method allows NADPH to be detected in the 2–175 μM concentration range, with a 0.6 μM detection limit. Graphical abstractSchematic of a top-down method for synthesizing fluorescent graphene oxide quantum dots (GOQD) by chemical degrading, exfoliation and self-assembly of graphene oxide (GO). The GOQDs display peroxidase-like activity and can oxidize dopamine to form a colored quinone that quenches the fluorescence of the GOQDs. The quenching efficiency is reduced, however, in the presence of NADP+.

中文翻译：

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使用橙色发光氧化石墨烯量子点开启荧光 NADPH 测定

摘要作者描述了一种合成氧化石墨烯量子点 (GOQD) 的方法，该量子点具有橙色荧光，其发射波长可通过改变激发波长在 537 至 593 nm 范围内进行调谐。GOQD 显示过氧化物酶模拟催化活性。具体来说，它们催化多巴胺氧化产生 4-(2-aminoethyl)benzo-1,2-quinone (AQ)，它是有色的，可以淬灭 GOQDs 的荧光。然而，通过添加 NADP+ 而不是通过其还原形式 (NADPH) 逆转淬灭。基于这些发现，制定了一种检测方法来监测涉及 NADP+ 的酶促反应。该方法允许在 2–175 μM 浓度范围内检测 NADPH，检测限为 0.6 μM。通过氧化石墨烯 (GO) 的化学降解、剥离和自组装合成荧光氧化石墨烯量子点 (GOQD) 的自上而下方法示意图。GOQDs 显示过氧化物酶样活性，可以氧化多巴胺形成有色醌，淬灭 GOQDs 的荧光。然而，在 NADP+ 存在的情况下，淬灭效率会降低。