【摘要】 介绍了基于交流阻抗技术构建非标记型脱氧核糖核酸（DNA）杂交传感器的方法．以24个碱基长度的寡聚DNA作为实验对象,将5′端巯基化的单链寡聚DNA（SH-ssDNA）探针与巯基乙酸（RSH）同时自组装到金电极表面,形成杂交识别层,利用交流阻抗技术测量出杂交前后金电极表面电子传递电阻R_et的增量作为杂交信号．实验中对DNA探针的自组装时间、杂交温度、杂交时间和阻抗测量液等实验条件进行了观察和优化；通过选择自组装液中SH-ssDNA探针和RSH的浓度,减少DNA在金电极表面的非特异性吸附,同时保证金电极表面自组装的SH-ssDNA探针有合适的疏密度,提高了杂交效率．在各优化条件下,无需扩增杂交信号,此非标记型DNA杂交传感器的检测下限为3．0×10^-14mol/L；和完全互补序列相比,一个和三个碱基错配序列分别产生55．6％和1．3％的杂交信号．更多还原

【Abstract】 A label-free DNA hybridization biosensor based on impedance technique was intro- duced.A 24-mer 5’-mercapto-group ended single-stranded DNA probe（SH-ssDNA）was self-as- sembled onto Au electrode surface with mercaptoacetic acid（RSH）to form a recognition layer. By Faradic impedance technique,a significant increase of the interracial electronic transfer resist- ance R_et was determined when the SH-ssDNA probe/Au electrode hybridized with its comple- mentary sequence.Further,several experimental conditions,including the SH-ssDNA probe im- mobilization time,hybridization temperature and time,the eletrolyte for impendance detections were optimized.Especially,the proportion of SH-ssDNA and RSH in the immobilization solu- tion was important for a suitable density of ssDNA probe on electrode surface to improve the hy- bridization efficiency.Based on these optimized conditions,this label-free DNA hybridization biosensor has a low detection limit of 3.0×10¹⁴ mol/L of complementary sequence in solution. When compared with the complementary sequence,the hybridization signal of one-base mis- matched sequence and three-base mismatched sequence was 55.6% and 1.3% respectively.更多还原