A mechanistic study of electron transfer from the distal termini of electrode-bound, single-stranded DNAs.
A mechanistic study of electron transfer from the distal termini of electrode-bound, single-stranded DNAs.
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DOI：
10.1021/ja106345d
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发表时间：
2010-11-17
影响因子：
15
通讯作者：
Plaxco KW
中科院分区：
文献类型：
--
作者：
Uzawa T;Cheng RR;White RJ;Makarov DE;Plaxco KW
电极结合，氧化还原-报告修饰的寡核苷酸在许多电化学生物传感器的功能中发挥作用，因此电子通过或从这些分子转移的问题已被证明是重要的兴趣。作为回应，我们通过实验表征了电子在短单链聚胸腺嘧啶DNA远端亚甲基蓝到DNA另一端特异性附着的单层涂覆金电极之间转移的速率。我们发现这个速率与寡核苷酸长度的比例为- 1.16±0.09次方。这种弱的、近似逆的长度依赖关系与单链DNA端到端碰撞速率和通过寡核苷酸电子跳跃所观察到的更强的依赖关系有很大不同。相反，它与反应有限过程的预期长度依赖一致，其中总体速率与寡核苷酸链末端接近表面的平衡概率成正比。对电子转移的离子强度和粘度依赖性的研究进一步支持了这种“链柔性”机制，对亚甲基蓝附着在己硫醇单层上的电子转移速率的研究表明，通过单层的非均相电子转移是限速的。因此，在我们所采用的情况下，寡核苷酸链的灵活性（即平衡统计特性）决定了附着的氧化还原报告文件将电子转移到底层电极的速率，这一观察结果可能在设计新的生物传感器结构时有用。
Electrode-bound, redox-reporter-modified oligonucleotides play roles in the functioning of a number of electrochemical biosensors, and thus the question of electron transfer through or from such molecules has proven of significant interest. In response, we have experimentally characterized the rate with which electrons are transferred between a methylene blue on the distal end of a short, single-stranded polythymine DNAs to a monolayer-coated gold electrode to which the other end of the DNA is site-specifically attached. We find that this rate scales with oligonucleotide length to the −1.16±0.09 power. This weak, approximately inverse length dependence differs dramatically from the much stronger dependencies observed for the rates of end-to-end collisions in single-stranded DNA and through-oligonucleotide electron hopping. It instead coincides with the expected length dependence of a reaction-limited process in which the overall rate is proportional to the equilibrium probability that the end of the oligonucleotide chain approaches the surface. Studies of the ionic strength and viscosity dependencies of electron transfer further support this “chain-flexibility” mechanism, and studies of the electron transfer rate of methylene blue attached to the hexanethiol monolayer suggest that heterogeneous electron transfer through the monolayer is rate limiting. Thus, under the circumstances we have employed, the flexibility (i.e., the equilibrium statistical properties) of the oligonucleotide chain defines the rate with which an attached redox reporter transfers electrons to an underlying electrode, an observation that may be of utility in the design of new biosensor architectures.
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影响因子：
4.7
作者：
Gorodetsky, Alon A.;Buzzeo, Marisa C.;Barton, Jacqueline K.
通讯作者：
Barton, Jacqueline K.
影响因子：
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作者：
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作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
5
作者：
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