Characterization of Oriented Thin Films of DNA

脱氧核糖核酸（DNA）是重要的生物信息来源，取决于其碱基序列。DNA也是一种有趣的分子材料，它显示出具有碱基对堆叠的长棒状双链体结构-碱基间隔为3.4 μ m，而双链体的直径约为20 μ m，因此似乎是沿着堆叠碱基的p电子云沿着进行一维能量转移和传导的良好候选者。本文综述了DNA定向LB膜的制备方法及其各向异性电子电导率。在鲑鱼睾丸DNA和嵌入剂溴化乙锭的水溶液中，制备了阳离子脂质的Langmuir单层膜，并将DNA-脂质复合物转移到基底上。极化吸收光谱证实DNA链沿沿着倾斜方向排列。当DNA膜以DNA链垂直于两个Au电极排列的形式放置在梳形电极上时，观察到大的欧姆电流，其随着施加电压的增加而线性增加，直到0.1V。相反，当膜以DNA链垂直于两个电极排列的形式放置时，即使在0.1V的电压下也几乎观察不到电流。

Deoxyribonucleic acids (DNAs) are important as a source of biological information depending on their base sequences. DNA is also interesting as a molecular material that shows a long rod-like duplex structure with base-pair stacking-the base separation is 3.4 Å while the diameter of the duplex is about 20 Å, therefore appears to be a good candidate for one-dimensional energy transfer and conduction along the p electron clouds of the stacked bases.In this report, we summarize preparations of DNA-aligned Langmuir-Blodgett (LB) film and its anisotropic electron conductivity.The DNA aligned film was prepared as follows. On the aqueous solution of DNA from Salmon testes and intercalator (ethidium bromide), Langmuir monolayer of cationic lipids were prepared, and DNA-lipid complexes were transferred on a substrate. It was confirmed by polarized absorption spectra that DNA strands aligned along a dipping direction.The dc conductivity was measured by using an ammeter in atmosphere. When the DNA film was put on the comb-shaped electrode as DNA strands aligned perpendicularly to two Au electrodes, a large ohmic current was observed that increased linearly with increasing the applied voltage up to 0.1 V. On the contrary, when the film was put as DNA strands aligned parallelly to two electrodes, electric current was hardly observed even at the voltage of 0.1 v.