Electrochemistry of methylene blue bound to a DNA-modified electrode
Electrochemistry of methylene blue bound to a DNA-modified electrode
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DOI：
10.1021/bc960070o
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发表时间：
1997-01-01
影响因子：
4.7
通讯作者：
Hill, MG
中科院分区：
文献类型：
--
作者：
Kelley, SO;Barton, JK;Hill, MG
金表面已经用含有悬垂的5'己基乙撑基连接物的15个碱基对双链DNA寡核苷酸衍生化。研究了插层亚甲基蓝在该修饰电极上的电化学行为。计时库仑法、循环伏安法、椭圆偏振法和通过P-32标记的定量都与大于或等于75%的表面覆盖率一致，其中DNA螺旋从电极表面以一定角度堆叠。循环伏安法在低亚甲蓝/双化学计量产生良好的表现表面波与E度= -0.25 V（相对于SCE），一个值0.03 V负的水溶液中。用库仑滴定法测得亚甲蓝在双链序列5' SH-（CH 2）（6）-p-AGTACAGTCATCGCG 3'衍生化的电极上的结合等温线，亲和常数等于3.8（5）× 10（6）M（-1），饱和值为每个DNA双链体1.4（2）个亚甲蓝嵌入剂。两者合计，这些实验支持一个模型的表面形态，其中DNA双链体是密集包装的，因此，亚甲蓝可逆地结合到网站的DNA接近散装溶液。电化学在DNA衍生电极提供了一个有价值的方法来检查DNA结合的氧化还原反应，并可能提供新的见解DNA介导的电子转移。
Gold surfaces have been derivatized with 15-base-pair double-stranded DNA oligonucleotides containing a pendant 5' hexanethiol linker. The electrochemistry of intercalated methylene blue has been investigated at these modified electrodes. Chronocoulometry, cyclic voltammetry, ellipsometry, and quantitation via P-32 labeling are all consistent with a surface coverage of greater than or equal to 75% with the DNA helices stacked at an angle from the electrode surface. Cyclic voltammetry at low methylene blue/duplex stoichiometries yields well-behaved surface waves with E degrees = -0.25 V (vs SCE), a value 0.03 V negative of that in aqueous solution. A binding isotherm for methylene blue at an electrode derivatized with the double-stranded sequence 5' SH-(CH2)(6)-p-AGTACAGTCATCGCG 3' was obtained from coulometric titrations and gave an affinity constant equal to 3.8(5) x 10(6) M(-1) with a saturation value of 1.4(2) methylene blue intercalators per DNA duplex. Taken together, these experiments support a model for the surface morphology in which DNA duplexes are densely packed; methylene blue therefore reversibly binds to sites in the DNA that are close to the bulk solution. Electrochemistry at DNA-derivatized electrodes provides a valuable methodology to examine DNA-bound redox reactions and may offer new insight into DNA-mediated electron transfers.