Composition and Structure of Fluorescent Graphene Quantum Dots Generated by Enzymatic Degradation of Graphene Oxide
Composition and Structure of Fluorescent Graphene Quantum Dots Generated by Enzymatic Degradation of Graphene Oxide
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DOI：
10.1021/acs.jpcc.1c01564
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发表时间：
2021-06
影响因子：
3.7
通讯作者：
Xiaoyun He;D. Sorescu;A. Star
中科院分区：
文献类型：
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作者：
Xiaoyun He;D. Sorescu;A. Star
由于碳纳米材料（CNM）与生物系统不可避免的接触，因此有必要对其代谢物进行研究，从而在材料和生命科学领域得到广泛应用。氧化石墨烯 (GO) 以及其他类型的 CNM 可以被髓过氧化物酶 (MPO) 酶降解，髓过氧化物酶是一种在先天免疫反应过程中释放的酶。然而，酶降解产物既没有明确定义也没有被充分理解。 MPO 催化 GO 降解过程中产生的一些产物可以发出蓝色光致发光 (PL)，并被简单地称为石墨烯量子点 (GQD)，而没有进一步阐明其结构。在这项工作中，我们使用液相色谱-质谱法来分离和阐明 MPO 催化降解产物的化学结构。针对 GQD 开发了通用化学式筛选工作流程，GQD 以多环芳烃 (PAH) 的形式在降解产物中获得。使用密度泛函理论计算进一步提出了导致蓝色 PL 的 PAH 的结构。我们的结果表明，具有多个共轭苯环的结构很可能产生观察到的 PL。这项工作提供了对酶降解机制的见解，并为生物系统中 GO 的荧光成像提供了机会。
The wide applications of carbon nanomaterials (CNMs) in both materials and life sciences necessitate investigation of their metabolites due to the inevitable contact of CNMs and biological systems. Graphene oxide (GO), along with other types of CNMs, can be enzymatically degraded by myeloperoxidase (MPO), an enzyme released during the innate immune response. However, enzymatic degradation products are neither well-defined nor well-understood. Some products generated during MPO-catalyzed degradation of GO could emit blue photoluminescence (PL) and were simply dubbed graphene quantum dots (GQDs) without further elucidating their structures. In this work, we use liquid chromatography–mass spectrometry to isolate and elucidate chemical structures of the MPO-catalyzed degradation products. A general chemical formula screening workflow was developed for the GQDs, which are in the form of polyaromatic hydrocarbons (PAHs), obtained in the degradation products. Structures of the PAHs responsible for the blue PL were further proposed using density functional theory calculations. Our results indicated that structures with several conjugated benzene rings are likely to generate the observed PL. This work provides insights into the mechanism of enzymatic degradation and opens opportunities for fluorescence imaging of GO in biological systems.