Yu Lei, Huang Mingchuan, Wang Peng G, Zeng Xiangqun
Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA.
Anal Chem. 2007 Dec 1;79(23):8979-86. doi: 10.1021/ac071453q. Epub 2007 Oct 31.
An alpha-link mannose-conjugated acrylamide monomer was synthesized. This monomer was polymerized by free radical polymerization with acrylamide, a cross-linker, and a surface linker directly on the gold surface. The surface linker, with an active carbon-carbon double bond, was preimmobilized on the gold surface by the thiol anchor. Thus, a cross-linked mannose-conjugated polymer thin layer was grafted onto a gold surface. This thin layer of polymer showed high binding sensitivity and excellent selectivity to its target lectin, concanavalin A (Con A), surpassing the formerly used linear glycopolymer and self-assembled glycol monolayers, validated by the techniques of quartz crystal microbalance, atomic force microscopy, and surface plasmon resonance. Remarkable response was observed to Con A at a concentration as low as 5 x 10(-10) M. The response is proportional to the Con A concentration up to 10(-7) M in phosphate-buffered saline. The use of cross-linked polymer decreased the flexibility of the polymer backbone between the carbohydrate binding sites. Therefore, the cost of conformational entropy for multivalent binding was minimized. The binding constants of the so-prepared cross-linked polymer with Con A were measured to be between 2.5 x 10(6) and 3.2 x 10(6) M(-1). These values are significantly larger than that obtained in our early study with a carbohydrate self-assembled monolayer. In addition to the carbohydrate-lectin recognition, additional selectivity may be achieved by controlling the degree of cross-linking.
合成了一种α-连接的甘露糖共轭丙烯酰胺单体。该单体通过自由基聚合与丙烯酰胺、交联剂和表面连接剂直接在金表面进行聚合。具有活性碳-碳双键的表面连接剂通过硫醇锚预先固定在金表面。因此，交联的甘露糖共轭聚合物薄层接枝到了金表面。通过石英晶体微天平、原子力显微镜和表面等离子体共振技术验证，该聚合物薄层对其靶标凝集素伴刀豆球蛋白A（Con A）表现出高结合灵敏度和优异的选择性，超过了以前使用的线性糖聚合物和自组装糖单层。在低至5×10⁻¹⁰ M的浓度下对Con A观察到了显著响应。在磷酸盐缓冲盐水中，响应与Con A浓度成正比，直至10⁻⁷ M。交联聚合物的使用降低了碳水化合物结合位点之间聚合物主链的柔韧性。因此，多价结合的构象熵成本最小化。所制备的交联聚合物与Con A的结合常数经测量在2.5×10⁶至3.2×10⁶ M⁻¹之间。这些值明显大于我们早期使用碳水化合物自组装单层研究中获得的值。除了碳水化合物-凝集素识别外，通过控制交联程度还可以实现额外的选择性。
