title: Self-assembled DNA monolayer buffered dynamic ranges of mercuric electrochemical sensor.
abstract: 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 Hg(2+) with a pair of thymine (T) formed between the two proximate poly(T) oligonucleotides on the electrode surface and Hg(2+) binding induced DNA strand displacement of ferrocene tagged poly(A). There are three types of T-Hg(2+)-T 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 Hg(2+) 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.
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing 100048, China. xinhuilou@cnu.edu.cn
authors.forename: Xinhui
authors.initials: X
authors.lastname: Lou
authors.forename: Tao
authors.initials: T
authors.lastname: Zhao
authors.forename: Ran
authors.initials: R
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Ma
authors.forename: Yi
authors.initials: Y
authors.lastname: Xiao
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002021:Buffers; D015342:DNA Probes / Q000737:chemistry*; D004553:Electric Conductivity; D004563:Electrochemistry; D005240:Feasibility Studies; D057230:Limit of Detection; D008628:Mercury / Q000032:analysis* / Q000737:chemistry*; D009693:Nucleic Acid Hybridization; D013499:Surface Properties
chemical_list: D002021:Buffers; D015342:DNA Probes; D008628:Mercury