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A
FM成像,
硫普罗宁/二氮杂
菲MPC与DNA的结合得到了可视化。