Herein we report the synthesis, intercalating properties, and analytical applications of an imidazole-substituted naphthalene diimide, N,N‘-bis(3-propylimidazole)-1,4,5,8-naphthalene diimide (PIND), functionalized with electrocatalytic redox moieties. PIND was prepared in a single-step reaction from the corresponding dianhydride. Attachment of the redox moieties to PIND relied upon ligand exchange with one of the liable chloride ligands of an Os(bpy)2Cl2 (bpy = 2,2‘-bipyridine) complex. The Os(bpy)2Cl2 complex was grafted onto PIND through coordinative bonds with the two imidazole groups at its termini, forming a PIND−[Os(bpy)2Cl]+ compound (PIND−Os). Gel electrophoretic studies revealed that PIND−Os binds more strongly to double-stranded DNA (ds-DNA) than its parent compound 1,4,5,8-naphthalene diimide. The naphthalene diimide group binds to ds-DNA in a “classical” threading intercalation mode, while the two Os(bpy)2Cl+ pendants interact with DNA via electrostatic interaction, reinforcing the intercalation by “locking up” the naphthalene diimide group in place. An electrochemical biosensor was fabricated using the redox-active and catalytic PIND−Os intercalator. An increase in sensitivity of 2500-fold over direct voltammetry was obtained in electrocatalytic amperometry, making this an interesting system for amperometric DNA sensing. Under optimized experimental conditions, the biosensor allowed the detection of a 50-mer target DNA in the range of 1.0−300 pM with a detection limit of 600 fM (1.5 amol, 23 fg).
在此,我们报告了一种
咪唑取代的
萘二
亚胺--N,N'-双(3-丙基
咪唑)-1,4,5,8-
萘二
亚胺(
PIND)--的合成、插层特性和分析应用。
PIND 由相应的二酐通过一步反应制备而成。氧化还原分子与
PIND 的连接依赖于与 Os(bpy)2Cl2(bpy =
2,2'-联吡啶)络合物的一个
氯化
配体的
配体交换。Os(bpy)2Cl2 复合物通过其端部的两个
咪唑基团的配位键接枝到
PIND 上,形成
PIND-[Os(bpy)2Cl]+化合物(
PIND-Os)。凝胶电泳研究显示,
PIND-Os 与双链 DNA(ds-DNA)的结合力强于其母体化合物 1,4,5,8-
萘二
亚胺。
萘二
亚胺基团以 "经典 "穿插模式与 ds-DNA 结合,而两个 Os(bpy)2Cl+ 垂体则通过静电作用与 DNA 相互作用,通过 "锁住 "
萘二
亚胺基团来加强穿插作用。利用这种具有氧化还原活性和催化作用的
PIND-Os 插层物,制造出了一种电
化学生物传感器。在电催化安培法中,灵敏度比直接伏安法提高了 2500 倍,使其成为一个有趣的安培 DNA 检测系统。在优化的实验条件下,该
生物传感器可检测 1.0-300 pM 范围内的 50 个目标 DNA,检测限为 600 fM(1.5 amol,23 fg)。