Enzyme-assisted cycling amplification and DNA-templated in-situ deposition of silver nanoparticles for the sensitive electrochemical detection of Hg(2.).
Enzyme-assisted cycling amplification and DNA-templated in-situ deposition of silver nanoparticles for the sensitive electrochemical detection of Hg(2.).
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DOI：
10.1016/j.bios.2016.07.035
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发表时间：
2016-12
影响因子：
12.6
通讯作者：
Hua Xie;Qin Wang;Y. Chai;Yali Yuan;R. Yuan
中科院分区：
文献类型：
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作者：
Hua Xie;Qin Wang;Y. Chai;Yali Yuan;R. Yuan
在这项工作中，开发了一种无标记的电化学生物传感器，用于灵敏和选择性地检测汞（II）离子（Hg2+），该传感器基于离子原位沉积银纳米粒子（AgNPs）在末端脱氧核苷酸转移酶（TdT）延伸的ssDNA上进行信号输出和切割核酸内切酶进行循环扩增。在靶Hg2+存在的情况下，富t DNA （HP1）可以通过at -Hg2+-T碱基对部分折叠成双工样结构（称为输出DNA），从而暴露其粘端。输出DNA粘端可与电极表面3′- po4端捕获DNA （HP2）杂交，形成输出DNA-HP2杂交复合物，序列为5′-CCTCAGC-3′/3′-GGAGTCG-5′（该序列可被切入核酸内切酶Nt. BbvCI识别）。随着Nt. BbvCI的引入，存在于杂交复合体中的输出DNA从电极上释放出来，参与下一个杂交过程，伴随着HP2的切割，暴露出大量的3 ' -OH基团，在TdT和脱氧腺苷三磷酸（dATP）的帮助下，可以延伸成一个长的ssDNA纳米尾巴。由于长带负电荷的ssDNA纳米尾巴吸收了DNA骨架上带正电荷的银离子，在加入还原试剂硼氢化钠后，金属银可以原位沉积在电极表面，用于电化学信号输出。在最佳条件下，所研制的电化学生物传感器对Hg2+具有良好的响应，检出限为3 pM （S/N=3）。此外，该传感器对其他干扰离子具有良好的再现性和选择性。该传感系统在实际样品分析中也有很好的应用前景。
In this work, a label-free electrochemical biosensor was developed for sensitive and selective detection of mercury (II) ions (Hg2+) based onin-situdeposition of silver nanoparticles (AgNPs) on terminal deoxynucleotidyl transferase (TdT) extended ssDNA for signal output and nicking endonuclease for cycling amplification. In the presence of target Hg2+, the T-rich DNA (HP1) could partly fold into duplex-like structure (termed as output DNA)viaT-Hg2+-T base pairs and thus exposed its sticky end. The sticky end of output DNA could then hybridize with 3′-PO4terminated capture DNA (HP2) on electrode surface to form output DNA-HP2 hybridization complex with the sequence 5′-CCTCAGC-3′/3′-GGAGTCG-5′ (the sequence could be recognized by nicking endonuclease Nt. BbvCI). With the introduction of Nt. BbvCI, output DNA existed in hybridization complex was released from electrode and participated in the next hybridization process, accompanying with the cleave of HP2 to expose substantial 3′-OH group, which could be extended into a long ssDNA nanotail with the aid of TdT and deoxyadenosine triphosphate (dATP). Since the long negatively charged ssDNA nanotail absorbed the positively charged silver ions on the DNA skeleton, the metallic silver could bein-situdeposited on electrode surface for electrochemical signal output upon addition of reduction regent sodium borohydride. Under optimal conditions, the developed electrochemical biosensor presented a good response to Hg2+with a detection limit of 3 pM (S/N=3). Furthermore, the biosensor exhibited good reproducibility and high selectivity towards other interfering ions. The proposed sensing system also showed a promising potential application in real sample analysis.