中文摘要：

采用简单的搅拌还原法制备了石墨烯/铜-银合金纳米复合物，基于该复合物修饰玻碳电极制备了新型的电化学传感器．用SEM和TEM扫描电镜对石墨烯和石墨烯/铜-银合金纳米复合物进行了表征．分别用循环伏安法和差分脉冲伏安法研究了鸟嘌呤和腺嘌呤在修饰电极上的电化学行为．结果表明，石墨烯/铜-银合金纳米复合膜显著促进了鸟嘌呤和腺嘌呤在电极上的电子传递速度．在0．1 mol/L醋酸盐缓冲溶液（ABS）中（pH 4．5），鸟嘌呤和腺嘌呤在该修饰电极上具有良好的电化学行为，鸟嘌呤和腺嘌呤分别在1．0～100．0μmol/L浓度范围内，信号线性关系良好，相关系数分别为0．997和0．998．鸟嘌呤和腺嘌呤的检出限分别为6．0×10^-8 mol/L和5．0×10^-8 mol/L（S/N ＝3）．将该传感器用于DNA样品中嘌呤碱基分析，得到（G ＋C）/（A ＋T）的比值为0．79．

英文摘要：

Graphene/Cu-Ag composites were prepared by a simple stirring reduction procedure. A novel electrochemical sensor was developed based on graphene/Cu-Ag composites modified glassy carbon electrode. The as-prepared graphene/Cu-Ag composites were characterized by scanning electron microscope and transmission electron microscope. The electrochemical behaviors of guanine and adenine on the modified electrode were investigated by cyclic voltammetry and differential pulse voltammetry. The results showed that the graphene/Cu-Ag composites film greatly accelerate the electron transfer of the analytes on the electrode in 0. 1 mol/L pH 4. 5 acetate buffer solutions. The concentration of guanine and adenine showed good linear relationships with the oxidation peak current in the range of 1. 0 - 100. 0 μmol/L with correlation coefficients of R = 0. 997 and 0. 998, respectively. The limits of detection for guanine and adenine were 6. 0 ×10^-8 mol/L and 5. 0 × 10^-8 mol/L （S/N = 3）, respectively. Furthermore, the measurements of thermally denatured single-stranded DNA with the as-prepared sensor were carried out and the value of （G ＋C）/（A ＋T） of single-stranded DNA was calculated to be 0. 79.