Selective DNA detection at Zeptomole level based on coulometric measurement of gold nanoparticle-mediated electron transfer across a self-assembled monolayer  

作　　者：WANG Wei YUAN XiaQing LIU XuHui GAO Qiang QI HongLan ZHANG ChengXiao 

机构地区：[1]Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education [2]School of Chemistry and Chemical Engineering, Shaanxi Normal University

出　　处：《Science China Chemistry》2013年第7期1009-1016,共8页中国科学（化学英文版）

基　　金：the financial support from The National Nature Science Foundation of China (21175089 and 20805029);Program for Changjiang Scholars and Innovative Research Team in University (IRT 1070)

摘　　要：A selective DNA sensing with zeptomole detection level is developed based on coulometric measurement of gold nanoparticle （AuNPs）-mediated electron transfer （ET） across a self-assembled monolayer on the gold electrode. After immobilization of a thiolated hairpin-structured DNA probe, an alkanethiol monolayer was self-assembled on the resultant electrode to block [Fe（CN）6]3-/4 in a solution from accessing the electrode. In the presence of DNA target, hybridization between the DNA probe and the DNA target breaks the stem duplex of DNA probe. Consequently, stem moiety at the 3＇-end of the DNA probes was removed from the electrode surface and made available for hybridization with the reporter DNA-AuNPs conjugates （reporter DNA-AuNPs）. The thiolated reporter DNA matches the stem moiety at the 3＇-end of the DNA probe. AuNPs were then en- larged by immersing the electrode in a growth solution containing HAuCI4 and H202 after the reporter DNA-AuNPs bound onto the electrode surface. The enlarged AuNPs on the electrode restored the ET between the electrode and the [Fe（CN）6]3 -/4-, as a result, amplified signals were achieved for DNA target detection using the coulometric measurement of Fe（CN）63- elec- tro-reduction by prolonging the electrolysis time. The quantities of ET on the DNA sensor increased with the increase in DNA target concentration through a linear range of 3.0 fM to 1.0 pM when electrolysis time was set to 300 s, and the detection limit was 1.0 fM. Correspondingly, thousands of DNA （zeptomole） copies were detected in 10-μL samples. Furthermore, the DNA sensor showed excellent differentiation ability for single-base mismatch.A selective DNA sensing with zeptomole detection level is developed based on coulometric measurement of gold nanoparticle (AuNPs)-mediated electron transfer (ET) across a self-assembled monolayer on the gold electrode. After immobilization of a thiolated hairpin-structured DNA probe, an alkanethiol monolayer was self-assembled on the resultant electrode to block [Fe(CN)6 ]-3-/4in a solution from accessing the electrode. In the presence of DNA target, hybridization between the DNA probe and the DNA target breaks the stem duplex of DNA probe. Consequently, stem moiety at the 3′-end of the DNA probes was removed from the electrode surface and made available for hybridization with the reporter DNA-AuNPs conjugates (reporter DNA-AuNPs). The thiolated reporter DNA matches the stem moiety at the 3′-end of the DNA probe. AuNPs were then enlarged by immersing the electrode in a growth solution containing HAuCl 4 and H2O2 after the reporter DNA-AuNPs bound onto the electrode surface. The enlarged AuNPs on the electrode restored the ET between the electrode and the [Fe(CN)6]3 -/4- , as a result, amplified signals were achieved for DNA target detection using the coulometric measurement of Fe(CN)6 3- electro-reduction by prolonging the electrolysis time. The quantities of ET on the DNA sensor increased with the increase in DNA target concentration through a linear range of 3.0 fM to 1.0 pM when electrolysis time was set to 300 s, and the detection limit was 1.0 fM. Correspondingly, thousands of DNA (zeptomole) copies were detected in 10L samples. Furthermore, the DNA sensor showed excellent differentiation ability for single-base mismatch.

关 键 词：DNA sensor coulometric hairpin DNA DNA-AuNPs conjugate ENLARGEMENT 

分 类 号：Q523[生物学—生物化学] TB383.1[一般工业技术—材料科学与工程]