Weng Jian, Zhang Jianfeng, Li Hui, Sun Liping, Lin Chenghong, Zhang Qiqing
Research Center of Biomedical Engineering, College of Materials, Technology Research Center of Biomedical Engineering of Xiamen City, The Key Laboratory of Biomedical Engineering of Fujian Province, Xiamen University, PR China.
Anal Chem. 2008 Sep 15;80(18):7075-83. doi: 10.1021/ac800610z. Epub 2008 Aug 16.
An electrochemical biosensor using a boron-doped diamond (BDD) electrode is described for differentiating between gene sequences according to DNA hybridization events using an ac impedimetric approach. BDD electrodes were dipped into a 1% solution of polyethylenimine (PEI) to adsorb a thin layer of positively charged PEI on the surface of BDD, then PEI-modified BDD electrodes were used to immobilize negatively charged single-stranded PCR fragments from Exon 7 of human p53 gene. Alternating current impedimetric measurements were first performed on these systems in phosphate buffered saline (PBS) and then upon exposure to single-stranded DNA (ssDNA). When the ssDNA-immobilized BDD electrode and solution ssDNA were completely complementary, a large drop in impedance was measured. Complementary DNA could be clearly detected at concentrations down to 10 (-19) g mL (-1) at a fixed frequency (10 Hz). Higher concentrations of DNA gave faster hybridization with saturation occurring at levels above 1.0 pg mL (-1.) Responses were much lower upon exposure to noncDNA, even at higher concentrations. The results show it is possible to directly detect target DNA at a fixed frequency and without additional labeling.
描述了一种使用硼掺杂金刚石（BDD）电极的电化学生物传感器，该传感器采用交流阻抗法，根据DNA杂交事件来区分基因序列。将BDD电极浸入1%的聚乙烯亚胺（PEI）溶液中，使带正电荷的PEI薄层吸附在BDD表面，然后用PEI修饰的BDD电极固定来自人p53基因第7外显子的带负电荷的单链PCR片段。首先在磷酸盐缓冲盐水（PBS）中对这些系统进行交流阻抗测量，然后在暴露于单链DNA（ssDNA）时进行测量。当固定有ssDNA的BDD电极与溶液中的ssDNA完全互补时，测量到阻抗大幅下降。在固定频率（10 Hz）下，浓度低至10（-19）g mL（-1）时也能清晰检测到互补DNA。DNA浓度越高，杂交速度越快，在高于1.0 pg mL（-1）的水平时达到饱和。即使在较高浓度下，暴露于非互补DNA时的响应也低得多。结果表明，有可能在固定频率下直接检测目标DNA，且无需额外标记。
