title: Oligonucleotide-functionalized silver nanoparticle extraction and laser-induced fluorescence for ultrasensitive detection of mercury(II) ion.
abstract: This study describes the development of a simple, sensitive, and selective detection system for Hg(2+) ion by combining nanoparticle extraction, fluorescent dye labeling, and flow injection analysis (FIA) detection. Repeats of 33 thymine nucleotides-functionalized silver nanoparticles (T(33)-AgNPs) specifically capture Hg(2+) from aqueous solution through the coordination between T(33) and Hg(2+). Meanwhile, Hg(2+) ion drives a T(33) conformational change from a random coil to a folded structure. The T(33)-Hg(2+)complexes adsorbed on the NP surface were collected from the initial sample by centrifugation, and they were then detached from the NP surface by addition of H(2)O(2). The T(33)-Hg(2+) complexes preferentially bind to SYBR Green I (SG), enhancing the SG fluorescence. By contrast, SG fluoresces only weakly in the presence of T(33) alone. The extraction efficiency of Hg(2+) was highly dependent on polythymine length, the concentration of T(33)-AgNPs, and the incubaton time of T(33)-AgNPs with Hg(2+). Under optimal extraction and labeling conditions, FIA detection showed the limit of detection (at a signal-to-noise ratio of three) for Hg(2+)of 3 pM. The selectivity of our analytical system is more than 1000-fold for Hg(2+) over any metal ions. We validated the applicability of this system for the determination of Hg(2+) concentrations in tap water.
authors.affiliation: Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan.
authors.forename: Zong-Han
authors.initials: ZH
authors.lastname: Wu
authors.forename: Jia-Hui
authors.initials: JH
authors.lastname: Lin
authors.forename: Wei-Lung
authors.initials: WL
authors.lastname: Tseng
mesh_terms: D052160:Benzothiazoles; D015374:Biosensing Techniques / Q000379:methods*; D003959:Diamines; D005453:Fluorescence; D006861:Hydrogen Peroxide / Q000737:chemistry; D007834:Lasers; D008628:Mercury / Q000737:chemistry / Q000302:isolation & purification*; D053758:Nanoparticles / Q000737:chemistry; D009841:Oligonucleotides / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry; D011804:Quinolines; D012834:Silver / Q000737:chemistry; D013942:Thymine Nucleotides / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D052160:Benzothiazoles; D003959:Diamines; D009841:Oligonucleotides; D009930:Organic Chemicals; D011804:Quinolines; D013942:Thymine Nucleotides; D014874:Water Pollutants, Chemical; C098022:SYBR Green I; D012834:Silver; D006861:Hydrogen Peroxide; D008628:Mercury