Nitrogen-doped graphene quantum dots (N-GQDs), with superior biocompatibility, strong resistance to photobleaching and convenient surface grafting, have sparked a surge of related-bio applications. In this study, combined with chromium picolinate (CrPic), N-GQDs synthesized by a facile hydrothermal approach are used to construct an environmentally-friendly sensor for the detection of cholesterol by exploiting the fluorescence enhancement of N-GQDs/CrPic. Herein, CrPic is grafted on N-GQDs via the linker of cysteamine (Cys), and the fluorescence of the N-GQDs is quenched by photoinduced electron transfer (PET), wherein CrPic functions as an electron donating group and the N-GQDs serves as an electron accepting group. Besides, cholesterol is stimulated to form a favourable complex with N-GQDs/CrPic because CrPic also acts as a potential receptor for cholesterol by strong affinity and π–π interaction, and the fluorescence of N-GQDs/CrPic is enhanced indicating that cholesterol could impede electron transfer from CrPic to the N-GQDs. This N-GQDs/CrPic-based sensor has been successfully applied to selectively determine the concentration of cholesterol with a linear range of 0–520 μM and a limit of detection (LOD) of 0.4 μM. Meanwhile, this present sensing strategy in human serum has acceptable practicability, reproducibility and precision.

中文翻译：

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使用基于氮的石墨烯量子点/吡啶甲酸铬络合物传感器对胆固醇进行荧光检测

氮掺杂石墨烯量子点（N-GQDs）具有卓越的生物相容性，强的抗光漂白性和便利的表面接枝，已引发了相关生物应用的激增。在这项研究中，结合吡啶甲酸铬（CrPic），通过简便的水热法合成的N-GQDs被用于构建环保的传感器，通过利用N-GQDs / CrPic的荧光增强来检测胆固醇。此处，CrPic通过以下方式嫁接到N-GQD上通过半胱胺（Cys）的连接基（Cys），N-GQDs的荧光通过光致电子转移（PET）猝灭，其中CrPic用作电子给体基团，N-GQDs用作电子接受基团。此外，胆固醇被刺激与N-GQDs / CrPic形成良好的复合物，因为CrPic还通过强亲和力和π-π相互作用充当胆固醇的潜在受体，并且N-GQDs / CrPic的荧光增强，表明胆固醇可以阻止电子从CrPic转移到N-GQD。这种基于N-GQDs / CrPic的传感器已成功应用于选择性测定胆固醇的浓度，其线性范围为0–520μM，检出限（LOD）为0.4μM。同时，目前在人血清中的传感策略具有可接受的实用性，可再现性和精确性。