Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai, People's Republic of China.
J Am Chem Soc. 2011 Mar 16;133(10):3649-57. doi: 10.1021/ja110478j. Epub 2011 Feb 22.
Carbohydrates represent one of the most significant natural building blocks, which govern numerous critical biological and pathological processes through specific carbohydrate-receptor interactions on the cell surface. We present here a new class of electrochemical probes based on gold surface-coated epimeric monosaccharide-quinone hybrids toward the ingenious detection of specific epimeric carbohydrate-protein interactions. Glucose and galactose, which represent a pair of natural monosaccharide C4 epimers, were used to closely and solidly conjugate with the 1,4-dimethoxybenzene moiety via a single C-C glycosidic bond, followed by the introduction of a sulfhydryl anchor. The functionalized aryl C-glycosides were sequentially coated on the gold electrode via the self-assembled monolayer (SAM) technique. X-ray photoelectron spectroscopy (XPS) was used to confirm the SAM formation, by which different binding energies (BE) between the glucosyl and the galactosyl SAMs on the surface, probably rendered by their epimeric identity, were observed. The subsequent electrochemical deprotection process readily furnished the surface-confined quinone/hydroquinone redox couple, leading to the formation of electrochemically active epimeric monosaccharide-quinone SAMs on the gold electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) used for the detection of specific sugar-lectin interactions indicated that the addition of specific lectin to the corresponding monosaccharide-quinone surface, i.e., concanavalin A (Con A) to the glucosyl SAM and peanut agglutinin (PNA) to the galactosyl SAM, resulted in an obvious decrease in peak current, whereas the addition of nonspecific lectins to the same SAMs gave very minor current variations. Such data suggested our uniquely constructed gold surface coated by sugar-quinone hybrids to be applicable as electrochemical probes for the detection of specific sugar-protein interactions, presumably leading to a new electrochemistry platform toward the study of carbohydrate-mediated intercellular recognitions.
碳水化合物是最重要的天然建筑块之一，通过细胞表面特定的碳水化合物-受体相互作用，控制着许多关键的生物和病理过程。我们在这里展示了一类基于金表面覆盖的差向异构单糖-醌杂合体的新型电化学探针，用于巧妙地检测特定的差向异构碳水化合物-蛋白质相互作用。葡萄糖和半乳糖是一对天然的 C4 差向异构体单糖，通过单 C-C 糖苷键与 1,4-二甲氧基苯部分紧密而牢固地连接，然后引入巯基锚。功能化芳基 C-糖苷通过自组装单层 (SAM) 技术顺序涂覆在金电极上。X 射线光电子能谱 (XPS) 用于确认 SAM 的形成，通过观察表面上葡糖基和半乳糖基 SAM 之间不同的结合能 (BE)，可能是由它们的差向异构身份引起的。随后的电化学去保护过程容易提供表面受限的醌/氢醌氧化还原对，导致电化学活性的差向异构单糖-醌 SAM 在金电极上形成。用于检测特定糖-凝集素相互作用的循环伏安法 (CV) 和差分脉冲伏安法 (DPV) 表明，将特定的凝集素添加到相应的单糖-醌表面，即伴刀豆球蛋白 A (Con A) 到葡糖基 SAM 和花生凝集素 (PNA) 到半乳糖基 SAM，会导致峰电流明显降低，而将非特异性凝集素添加到相同的 SAM 只会引起很小的电流变化。这些数据表明，我们独特构建的糖-醌杂合体涂覆的金表面可作为电化学探针用于检测特定的糖-蛋白质相互作用，可能为研究碳水化合物介导的细胞间识别提供新的电化学平台。
