Won Byoung Yeon, Yoon Hyun C, Park Hyun Gyu
Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea.
Analyst. 2008 Jan;133(1):100-4. doi: 10.1039/b712638g. Epub 2007 Oct 16.
The signal amplification technique of peptide nucleic acid (PNA)-based electrochemical DNA sensor was developed in a label-free and one-step method utilizing enzymatic catalysis. Electrochemical detection of DNA hybridization on a PNA-modified electrode is based on the change of surface charge caused by the hybridization of negatively charged DNA molecules. The negatively charged mediator, ferrocenedicarboxylic acid, cannot diffuse to the DNA hybridized electrode surface due to the charge repulsion with the hybridized DNA molecule while it can easily approach the neutral PNA-modified electrode surface without the hybridization. By employing glucose oxidase catalysis on this PNA-based electrochemical system, the oxidized mediator could be immediately reduced leading to greatly increased electrochemical signals. Using the enzymatic strategy, we successfully demonstrated its clinical utility by detecting one of the mutation sequences of the breast cancer susceptibility gene BRCA1 at a sample concentration lower than 10(-9) M. Furthermore, a single base-mismatched sample could be also discriminated from a perfectly matched sample.
基于肽核酸（PNA）的电化学DNA传感器的信号放大技术是利用酶催化以无标记一步法开发的。在PNA修饰电极上对DNA杂交进行电化学检测是基于带负电荷的DNA分子杂交引起的表面电荷变化。带负电荷的媒介体二茂铁二甲酸，由于与杂交的DNA分子存在电荷排斥，无法扩散到杂交DNA的电极表面，而在没有杂交的情况下，它可以轻松接近中性的PNA修饰电极表面。通过在这个基于PNA的电化学系统上采用葡萄糖氧化酶催化，氧化态的媒介体可以立即被还原，从而导致电化学信号大幅增加。利用这种酶促策略，我们通过在低于10（-9）M的样品浓度下检测乳腺癌易感基因BRCA1的一个突变序列，成功证明了其临床实用性。此外，还可以将单碱基错配的样品与完全匹配的样品区分开来。
