Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering , University of Alcalá , Alcala de Henares, Madrid E-28871 , Spain.
Department of Analytical Sciences, Faculty of Sciences , Universidad Nacional de Educación a Distancia (UNED) , Madrid E-28040 , Spain.
Anal Chem. 2019 Aug 6;91(15):10245-10250. doi: 10.1021/acs.analchem.9b02375. Epub 2019 Jul 18.
Glycoproteins are excellent biomarkers for diagnosis and prognosis of several illnesses. α-1-Acid glycoprotein (AGP) and transferrin (Tf) are the main glycoproteins present in the serum, whose levels are increased during disease or injury. In this work, a selective detection of these glycoproteins using a microchip electrophoresis-electrochemical detection (ME-ED) platform is proposed for the first time. Because of the reduced sensitivity of glycoproteins, they were labeled with an electrochemical tag (osmium(VI) complex), which binds only to glycans, increasing the amperometric signal. Interestingly, oxidation potential of glycoprotein-Os(VI) adducts started at +0.50 V (vs Ag/AgCl) while nontagged glycoproteins started at +0.60 V. So, when the detection potential is set at +0.50 V, only glycoproteins tagged with Os(VI) complex are detected, avoiding the interference of the rest of the proteins. Determination of AGP and Tf was successfully demonstrated in the analysis of a certified human serum reference material yielding excellent accuracy ( ≤ 4%) in just 400 s. This work offers new possibilities for ED for glycoprotein analysis in microfluidic systems, which has been dominated by fluorescence and MS detection until now. It is worth mentioning that ED has two interesting advantages with respect to others in the point-of-care testing field: easy miniaturization (bedside devices) and low cost.
糖蛋白是诊断和预测多种疾病的优秀生物标志物。α-1-酸性糖蛋白（AGP）和转铁蛋白（Tf）是血清中主要的糖蛋白，其水平在疾病或损伤时会升高。在这项工作中，首次提出使用微芯片电泳-电化学检测（ME-ED）平台选择性检测这些糖蛋白。由于糖蛋白的灵敏度降低，因此它们用电化学标记物（锇（VI）配合物）进行标记，该标记物仅与聚糖结合，从而增加了电流信号。有趣的是，糖蛋白-Os（VI）加合物的氧化电位在+0.50 V（相对于 Ag/AgCl）开始，而未标记的糖蛋白在+0.60 V 开始。因此，当检测电位设置为+0.50 V 时，只有用 Os（VI）配合物标记的糖蛋白被检测到，从而避免了其他蛋白质的干扰。在对经过认证的人血清参考物质的分析中成功地证明了 AGP 和 Tf 的测定，仅需 400 秒即可达到出色的准确度（≤4%）。这项工作为 ED 在微流控系统中的糖蛋白分析提供了新的可能性，直到现在，荧光和 MS 检测一直主导着 ED。值得一提的是，ED 在即时检测领域相对于其他检测方法具有两个有趣的优势：易于小型化（床边设备）和低成本。
