Department of Nanoscience and Engineering, Inje University, Gimhae, 50834, Republic of Korea.
Department of Nanoscience and Engineering, Inje University, Gimhae, 50834, Republic of Korea; School of Biomedical Engineering, Inje University, Gimhae, 50834, Republic of Korea.
Anal Chim Acta. 2021 Jun 22;1165:338513. doi: 10.1016/j.aca.2021.338513. Epub 2021 Apr 20.
Levodopa has been a standard drug for treating Parkinson's disease since the 1960s, but it has caused many side effects such as wearing-off, motor fluctuation, and dystonia. In this work, we developed glutathione-conjugated carbon quantum dots (GSH-CQDs) as a novel fluorescent sensor for sensitive and selective detection of levodopa. The GSH-CQDs were prepared by EDC/NHS coupling reaction of glutathione (GSH) with amine-functionalized CQDs (N-CQDs) synthesized using meta-phenylenediamine and ethylenediamine. The synthesized GSH-CQDs emitted bright green fluorescence with a high quantum yield (QY) of 22.42 ± 6.88%. However, upon the addition of levodopa to GSH-CQDs under alkaline conditions, the fluorescence of GSH-CQDs was quenched. Since levodopa is converted to dopaquinone in an alkaline environment, it is presumed that thiol groups of GHS-CQDs form covalent bonds with dopaquinone, causing fluorescence quenching through photoinduced electron transfer. Therefore, as the concentration of levodopa increased, the fluorescence intensity of GSH-CQDs was gradually decreased. Under optimal conditions, a linear response was observed in the range of 0.05-1 μM, and limit of detection (LOD) was determined to be 0.057 μM. The GSH-CQDs exhibited high specificity to levodopa over other non-target biological substances, quinone derivatives, and Parkinson's medications. Furthermore, the capability of this GSH-CQDs sensor for monitoring levodopa in human serum were validated with excellent precision and recovery rates of 100.20-103.33%.
左旋多巴自 20 世纪 60 年代以来一直是治疗帕金森病的标准药物，但它会引起许多副作用，如开-关现象、运动波动和肌张力障碍。在这项工作中，我们开发了谷胱甘肽偶联的碳量子点（GSH-CQDs）作为一种新型荧光传感器，用于灵敏和选择性检测左旋多巴。GSH-CQDs 通过谷胱甘肽（GSH）与通过间苯二胺和乙二胺合成的胺功能化 CQDs（N-CQDs）的 EDC/NHS 偶联反应制备。合成的 GSH-CQDs 发射明亮的绿色荧光，量子产率（QY）为 22.42±6.88%。然而，在碱性条件下将左旋多巴加入到 GSH-CQDs 中时，GSH-CQDs 的荧光被猝灭。由于在碱性环境中左旋多巴转化为多巴醌，因此推测 GHS-CQDs 的巯基与多巴醌形成共价键，通过光诱导电子转移导致荧光猝灭。因此，随着左旋多巴浓度的增加，GSH-CQDs 的荧光强度逐渐降低。在最佳条件下，在 0.05-1 μM 范围内观察到线性响应，检测限（LOD）确定为 0.057 μM。与其他非靶生物物质、醌衍生物和帕金森药物相比，GSH-CQDs 对左旋多巴表现出高特异性。此外，该 GSH-CQDs 传感器在监测人血清中的左旋多巴方面的性能通过出色的精密度和回收率（100.20-103.33%）得到验证。
