Ultraselective Homogeneous Electrochemical Biosensor for DNA Species Related to Oral Cancer Based on Nicking Endonuclease Assisted Target Recycling Amplification

详细信息    查看全文

• 作者：Yue Tan ; Xiaofeng Wei ; Mengmeng Zhao ; Bin Qiu ; Longhua Guo ; Zhenyu Lin ; Huang-Hao Yang
• 刊名：Analytical Chemistry
• 出版年：2015
• 出版时间：September 15, 2015
• 年：2015
• 卷：87
• 期：18
• 页码：9204-9208
• 全文大小：326K
• ISSN：1520-6882

文摘

Traditional electrochemical DNA biosensors need DNA immobilization on the electrode surface, which is tedious and time-consuming. In this study, a simple but ultraselective electrochemical DNA biosensor had been designed to determine target DNA species related to oral cancer overexpressed 1 in saliva, which combines the signal amplification of nicking endonuclease assisted target recycling with the immobilization-free electrochemical method. The complementary substrate strand of target DNA species contains a simple asymmetric sequence had been modified with a methylene blue at the 3鈥?terminal first, which cannot diffuse easily to the negative charged ITO electrode surface due to the abundant negative charges. The presence of the target DNA would trigger the formation of double-stranded DNA (dsDNA). Then the nicking endonuclease can recognize the simple asymmetric sequence in the dsDNA and cleave the substrate strand of ds-DNA into two pieces, a long ssDNA and a 2-base ssDNA linked with methylene blue. The short one can diffuse easily to the negative charged ITO electrode surface and results in the enhanced electrochemical response detected. At the same time, the target DNA can dissociate from the dsDNA and trigger the next round of hybridization, cleavage, and releasing, which results in the signal amplification. This homogeneous DNA biosensor can detect as low as 0.35 pM (S/N = 3) target DNA. Compared with the traditional heterogeneous electrochemical DNA biosensors, which are tedious and time-consuming due to the complex DNA immobilization process, the assay not only owns the merits of simple and high efficiency since performed in a homogeneous solution but also exhibits a high distinction ability to single-base mismatch, double-bases mismatch, and noncomplementary DNA sequence.