title: Sensitive label-free oligonucleotide-based microfluidic detection of mercury (II) ion by using exonuclease I.
abstract: Mercury is a highly toxic metal that can cause significant harm to humans and aquatic ecosystems. This paper describes a novel approach for mercury (Hg(2+)) ion detection by using label-free oligonucleotide probes and Escherichia coli exonuclease I (Exo I) in a microfluidic electrophoretic separated platform. Two single-stranded DNAs (ssDNA) TT-21 and TT-44 with 7 Thymine-Thymine mispairs are employed to capture mercury ions. Due to the coordination structure of T-Hg(2+)-T, these ssDNAs are folded into hairpin-like double-stranded DNAs (dsDNA) which are more difficult to be digested by Exo I, as confirmed by polyacrylamide gel electrophoresis (PAGE) analysis. A series of microfluidic capillary electrophoretic separation studies are carried out to investigate the effect of Exo I and mercury ion concentrations on the detected fluorescence intensity. This method has demonstrated a high sensitivity of mercury ion detection with the limit of detection around 15 nM or 3 ppb. An excellent selectivity of the probe for mercury ions over five interference ions Fe(3+), Cd(2+), Pb(2+), Cu(2+) and Ca(2+) is also revealed. This method could potentially be used for mercury ion detection with high sensitivity and reliability.
authors.affiliation: State Key Lab of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Rd, Shanghai 200050, China.
authors.forename: Min
authors.initials: M
authors.lastname: Yuan
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xinhui
authors.initials: X
authors.lastname: Lou
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.forename: Gang
authors.initials: G
authors.lastname: Wei
authors.forename: Minbo
authors.initials: M
authors.lastname: Lan
authors.forename: Jianlong
authors.initials: J
authors.lastname: Zhao
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004247:DNA / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005090:Exodeoxyribonucleases / Q000737:chemistry*; D007477:Ions; D008628:Mercury / Q000032:analysis* / Q000737:chemistry; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling
chemical_list: D007477:Ions; D004247:DNA; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I; D008628:Mercury