Department of Chemistry, University of Western Ontario, 1151 Richmond, Street, London, Ontario, Canada N6A 5B7.
Analyst. 2011 Aug 7;136(15):3107-12. doi: 10.1039/c1an15253j. Epub 2011 Jun 24.
While oligonucleotide hybridization and effects of nucleobase mismatches have been the intense focus of a number of electrochemical studies, the effects of the target strand length on the electrochemical response of oligonucleotide films have not been addressed yet. In this report, we have studied the electrochemical impedance of the oligonucleotide films having overhangs on either the target or the surface bound capture strand. Each system gives different impedance responses, which were interpreted with the help of modified Randles' equivalent. Results indicate that comparable sizes of target and capture strands ensure the higher hybridization efficiency and film order. The presence of nucleobase overhangs at the bottom of the film causes lower changes in charge transfer resistance (ΔR(CT)) after hybridization due to lower hybridization efficiency and presumably non-uniformity in the film. Nucleobase overhangs at the top of the film result in higher ΔR(CT) due to higher film order and accumulation of negative charges but appear not to cause any steric congestion.
尽管寡核苷酸杂交和碱基错配的影响已经成为许多电化学研究的焦点，但目标链长度对寡核苷酸膜电化学响应的影响尚未得到解决。在本报告中，我们研究了在目标或表面结合捕获链上具有悬垂部分的寡核苷酸膜的电化学阻抗。每个系统都给出了不同的阻抗响应，这些响应是借助改进的兰德尔等效电路来解释的。结果表明，目标链和捕获链具有可比的尺寸可确保更高的杂交效率和膜有序性。由于杂交效率较低且膜可能不均匀，因此在膜底部存在碱基悬垂部分会导致杂交后电荷转移电阻（ΔR（CT））的变化较小。在膜的顶部存在碱基悬垂部分会导致更高的 ΔR（CT），这是由于更高的膜有序性和负电荷的积累，但似乎不会引起任何空间位阻。
