Self-Assembled DNA Monolayer Buffered Dynamic Ranges of Mercuric Electrochemical Sensor

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• 作者：Xinhui Lou ; Tao Zhao ; Ran Liu ; Jie Ma ; Yi Xiao
• 刊名：Analytical Chemistry
• 出版年：2013
• 出版时间：August 6, 2013
• 年：2013
• 卷：85
• 期：15
• 页码：7574-7580
• 全文大小：325K
• 年卷期：v.85,no.15(August 6, 2013)
• ISSN：1520-6882

文摘

Sensors with wide dynamic ranges (DRs) are typically constructed by utilizing a set of ligands with varied affinities for the same target. We report here a novel buffer self-assembled monolayer (BSAM) strategy, to fabricate sensors with extraordinarily broad DRs using a single recognition ligand. We demonstrated the concept of BSAM by constructing the electrochemical mercuric sensors with different surface probe densities (SPD) on a gold electrode. These sensors are based on the coordination of Hg²⁺ with a pair of thymine (T) formed between the two proximate poly(T) oligonucleotides on the electrode surface and Hg²⁺ binding induced DNA strand displacement of ferrocene tagged poly(A). There are three types of T鈥揌g²⁺鈥揟 coordination: those formed between (a) two poly(T) strands where none are hybridized with poly(A) strands, thus contributing zero effect on releasing the signaling probe, (b) poly(A)/poly(T) hybridized and nonhybridized poly(T) strands, resulting in the release of a signaling probe from the surface; and (c) two poly(A)/poly(T) hybridized strands, causing the release of two signaling probes from the surface. The DRs from 10 pM to 0.1 mM at varied SPDs were observed, attributing to the tunable Hg²⁺ storage capability of the poly(T) SAM formed on the surface due to the coordination mechanism of (a) and (b). The DR was able to be further extended to 1 mM by using the longer poly(T) strands. The ready-to-use sensor exhibited great selectivity against the common interferential metal ions. As demonstrated, the BSAM strategy is a facile way to fabricate sensors with tunable and wide DRs.