DNA Binding of an Ethidium Intercalator Attached to a Monolayer-Protected Gold Cluster
作者:Gangli Wang、Jian Zhang、Royce W. Murray
DOI:10.1021/ac0257804
日期:2002.9.1
Ethidium intercalation has been investigated as a means of inducing binding of Au nanoparticles to DNA. The ethidium sites are attached to the nanoparticles as thiolate ligands, using 3,8-diamino-5-mercaptododecyl-6-phenylphenanthridinium (ethidium thiolate). Each nanoparticle bears only one or two ethidium thiolate ligands. The rest of the thiolate monolayer ligands on the monolayer-protected Au clusters (MPCs) were either N-(2-mercaptopropionyl)glycine (tiopronin/ethidium MPC) or trimethyl(mercaptoundecyl)ammonium (TMA/ethidium MPC). In solution mixtures of DNA and MPCs, the energy-transfer quenching of the ethidium ligands by the metal-like MPC core is partially released by ethidium binding to DNA, as observed by an increase in the intensity of ethidium fluorescence. Binding of the cationic TMA/ethidium MPC to DNA was efficient and rapid. The negatively charged tiopronin/ethidium MPC, in contrast, exhibits slow intercalation kinetics, relative to ethidium cation not attached to an MPC. The slow kinetics were analyzed as two competing binding interactions. The tiopronin/ethidium MPC binding to DNA was imaged by AFM.
二氮杂菲嵌入作为一种诱导金纳米粒子与DNA结合的手段已被研究。二氮杂菲位点通过硫醇配体连接到纳米粒子上,使用的是3,8-二氨基-5-巯基十二烷基-6-苯基菲啶(二氮杂菲硫醇)。每个纳米粒子仅含有一个或两个二氮杂菲硫醇配体。单层保护的金团簇(MPCs)上的其余硫醇单层配体要么是N-(2-巯基丙酸基)甘氨酸(硫普罗宁/二氮杂菲MPC),要么是三甲基(巯基十一烷基)铵(TMA/二氮杂菲MPC)。在DNA和MPCs的溶液混合物中,金属样MPC核心对二氮杂菲配体的能量转移淬灭部分被二氮杂菲与DNA的结合所释放,通过观察到二氮杂菲荧光强度的增加可以看出这一点。带正电的TMA/二氮杂菲MPC与DNA的结合是高效且迅速的。相比之下,带负电的硫普罗宁/二氮杂菲MPC相对于未附着在MPC上的二氮杂菲阳离子,显示出较慢的嵌入动力学。慢动力学被分析为两种竞争性结合作用的相互作用。通过AFM成像,硫普罗宁/二氮杂菲MPC与DNA的结合得到了可视化。