Fabrication of Carbohydrate Microarrays on Gold Surfaces: Direct Attachment of Nonderivatized Oligosaccharides to Hydrazide-Modified Self-Assembled Monolayers
作者:Zheng-liang Zhi、Andrew K. Powell、Jeremy E. Turnbull
DOI:10.1021/ac060084f
日期:2006.7.1
This paper describes a new and simple microarray platform for presenting multiple nonderivatized oligosaccharides to protein targets, with utility for mapping carbohydrate−protein recognition events. The approach is based on the creation of a hydrazide-derivatized, self-assembled monolayer on a gold surface in a single or two-step procedure, for efficient and selectively oriented anchoring of oligosaccharide probes via their reducing ends, with detection using fluorescence detection of bound proteins. The biggest hurdles in employing gold-based substrate for fluorescence-based microarray detection include fluorescence quenching and nonspecific surface adsorption of proteins. We found that the quenching effect could be minimized by introducing a ω-thiolated fatty acid (C16) self-assembled monolayer between the gold surface and hydrazide groups, followed by detection involving three successive binding protein layers covering the gold surface. In addition, an effective blocking scheme involving poly(ethylene glycol) aldehyde and bovine serum albumin was employed to reduce nonspecific protein adsorption to the chip surface. As proof of principle, we demonstrate here that sulfated oligosaccharide probes from heparin can be effectively and covalently attached without prior derivatization onto the hydrazide-modified, self-assembled monolayer on gold-coated slide surfaces in a microarray format. This platform is used to assess binding of specific heparin-binding protein targets at very high sensitivity, and we also demonstrate that the approach can be extended to nonsulfated sugars. Direct attachment of nonderivatized sugar probes on the chip is advantageous since it avoids the need for laborious prederivatization and cleanup steps. This versatile fluorescence microarray platform provides a facile approach for interrogating multiple carbohydrate−protein interactions in a high-throughput manner and has potential as a common gold surface platform for other diverse interrogations by MALDI-MS, surface plasmon resonance, and quartz crystal microbalances.
本文介绍了一种新的、简单的微阵列平台,可将多种非钝化寡糖呈现给蛋白质靶标,用于绘制碳水化合物-蛋白质识别事件图。该方法是通过单步或两步程序在金表面形成肼衍化的自组装单层,通过寡糖探针的还原端高效、选择性地定向锚定寡糖,并利用荧光检测结合蛋白。使用金基底进行荧光芯片检测的最大障碍包括荧光淬灭和蛋白质的非特异性表面吸附。我们发现,通过在金表面和酰肼基团之间引入ω-硫代脂肪酸(C16)自组装单层,可将淬灭效应降至最低,然后再通过覆盖金表面的三个连续结合蛋白层进行检测。此外,我们还采用了聚乙二醇醛和牛血清白蛋白的有效阻断方案,以减少芯片表面的非特异性蛋白质吸附。作为原理验证,我们在此证明了肝素硫酸化寡糖探针可以有效地共价连接到肼基修饰的自组装单层上,而无需事先衍生化。这一平台可用于评估特定肝素结合蛋白目标的结合,灵敏度非常高,我们还证明了这种方法可扩展到非硫酸化糖。在芯片上直接附着非钝化糖探针具有优势,因为它避免了费力的预钝化和清理步骤。这种多功能荧光芯片平台为高通量检测多种碳水化合物与蛋白质之间的相互作用提供了一种简便的方法,并有可能成为一种通用的金表面平台,用于通过 MALDI-MS、表面等离子体共振和石英晶体微天平进行其他多种检测。