移取1 g·L^-1氧化石墨烯悬浮液5 μL滴加在经抛光、清洗的玻碳电极表面，红外灯下烘干后，在0.1 mol·L^-1 KH₂PO₄溶液中，在-0.9 V下沉积600 s，然后将电极浸泡于100 μmol·L^-1连续鸟嘌呤碱基DNA溶液中1 h，得到氧化石墨烯-连续鸟嘌呤碱基DNA复合膜修饰电极。采用透射电子显微镜、扫描电子显微镜和电化学方法对修饰电极进行了表征，研究了多巴胺在此修饰电极上的电化学行为，结果发现此修饰电极对多巴胺的氧化还原具有明显的电催化作用。在pH 7.0的磷酸盐缓冲溶液中，以50 mV·s^-1的扫描速率扫描，记录多巴胺在修饰电极上的差分脉冲伏安曲线，结果发现多巴胺的浓度在5.0×10^-7~9.0×10^-6mol·L^-1，9.0×10^-6~5.0×10^-5mol·L^-1内与其氧化峰电流呈线性关系，检出限（3s/k）为3.5×10^-8mol·L^-1。方法可用于测定体液和药品中多巴胺的含量，加标回收率在88.0%~106%之间，测定值的相对标准偏差（n=5）小于5.0%。

5 μL of 1 g·L^-1 graphene oxide solution was dipped onto the surface of the polished and cleaned glassy carbon electrode. After dring under infrared light, the electrode was deposited in a 0.1 mol·L^-1 KH₂PO₄ solution at -0.9 V for 600 s. Then the electrode was immersed in 100 μmol·L^-1 continuous guanine DNA solution for 1 h to obtain a graphene oxide-continuous guanine DNA composite membrane modified electrode. The modified electrode was characterized by transmission electron microscopy, scanning electron microscopy and electrochemical method. The electrochemical behavior of dopamine at the modified electrode was studied. It was found that the modified electrode showed obvious electrocatalytic effect on the redox of dopamine. In phosphate buffer solution (pH 7.0), the differential pulse voltammograms of dopamine at the modified electrode were recorded at a scan rate of 50 mV·s^-1. Linear relationships were found between the oxidation peak current and the concentration of dopamine in the ranges of 5.0×10^-7-9.0×10^-6mol·L^-1, 9.0×10^-6-5.0×10^-5mol·L^-1, respectively, and the detection limit (3s/k) was 3.5×10^-8mol·L^-1. The method was used for determining the content of dopamine in body fluids and medicines, giving values of recovery obtained by standard additiom method between 88.0% and 106%, and RSDs (n=5) less than 5.0%.