In this paper, we report a highly sensitive chemiluminescence(CL) sensor for Hg2+ ions based on thymine-Hg2+-thymine(T-Hg2+-T) coordination chemistry. We designed a thymine rich oligonucleotide as a capture probe and ...In this paper, we report a highly sensitive chemiluminescence(CL) sensor for Hg2+ ions based on thymine-Hg2+-thymine(T-Hg2+-T) coordination chemistry. We designed a thymine rich oligonucleotide as a capture probe and a signal probe that includes two functional domains: a horseradish peroxidase-mimicking DNAzyme domain for the generation of CL, and a recognition domain. Graphene oxide(GO) was introduced to adsorb the signal probe via π-π interaction, which brought the DNAzyme domain and GO into close proximity and quenches CL. In the presence of Hg2+ ions, the coordination of Hg2+ with the capture probe yielded a hairpin complex, triggers cascaded strand displacement reactions and Exonuclease III-assisted signal amplifications. As a result, accumulated amounts of DNAzyme were generated and released from GO, leading to an enhanced CL signal. This strategy combines enzyme-based signal amplification and GO as a background reducer, leads to a limit of detection(LOD) of 2 nmol/L. This simple detection system provides a label-free yet sensitive approach for detection of Hg2+ ions.展开更多
As a global pollutant process, the reduction of mercury （Hg） is especially important. One pathway is through an abiotic reduction with humic acids （HAs）, which is controlled by different factors, including initial...As a global pollutant process, the reduction of mercury （Hg） is especially important. One pathway is through an abiotic reduction with humic acids （HAs）, which is controlled by different factors, including initial Hg and HA concentrations, pH, temperature and light. In this study, three humic acids were selected to illustrate the Hg2＋ abiotic reduction mechanisms by HAs, and to identify the key limiting factors for reduction rates and amounts. In addition, the initial status of the HAs as a solid or in an aqueous solution were also compared, to help explain why HAs show different dominant characteristics （e.g. complexation or reduction） in the reaction process with Hg. Results indicated that HAs were able to reduce Hg abiotically. Higher initial Hg, higher HA concentrations and either high （8.1） or low （3.6） solution pH decreased the HA reduction capacity. In addition, Hg~ production rates increased with increasing temperature, and the same trend was observed with light exposure. Humic acids added as an aqueous solution resulted in significantly greater HgO production than addition as a bulk solid. Finally, the Hg reduction rate and capacity varied significantly （P 〈 0.05） with HAs from different sources. These findings helped to explain why HAs showed different dominant characteristics （e.g. complexation or reduction） in the reaction process with of Hg2＋ reduction, which indicated that humic substances in sink or a source for Hg. Hg, and evidentially demonstrated the existence of a possible pathway natural environments, especially in water bodies, could act either as a展开更多
基金supported by the National Natural Science Foundation of China(21222508,21375073)the Shanghai Municipal Commission for Science and Technology(13QH1402300)+1 种基金the State Ethnic Affairs Commission(10ZY02)the 111 Project of Minzu University(B08044)
文摘In this paper, we report a highly sensitive chemiluminescence(CL) sensor for Hg2+ ions based on thymine-Hg2+-thymine(T-Hg2+-T) coordination chemistry. We designed a thymine rich oligonucleotide as a capture probe and a signal probe that includes two functional domains: a horseradish peroxidase-mimicking DNAzyme domain for the generation of CL, and a recognition domain. Graphene oxide(GO) was introduced to adsorb the signal probe via π-π interaction, which brought the DNAzyme domain and GO into close proximity and quenches CL. In the presence of Hg2+ ions, the coordination of Hg2+ with the capture probe yielded a hairpin complex, triggers cascaded strand displacement reactions and Exonuclease III-assisted signal amplifications. As a result, accumulated amounts of DNAzyme were generated and released from GO, leading to an enhanced CL signal. This strategy combines enzyme-based signal amplification and GO as a background reducer, leads to a limit of detection(LOD) of 2 nmol/L. This simple detection system provides a label-free yet sensitive approach for detection of Hg2+ ions.
基金Supported by the National Natural Science Foundation of China(No.40971147/D010503)the China Postdoctoral Science Foundation(No.2013M542238)+1 种基金the Fundamental Research Funds for The Central Universities,China(No.XDJK2013C151)the Ph.D.Initiation Fund of Southwest University,China(No.SWU112098)
文摘As a global pollutant process, the reduction of mercury （Hg） is especially important. One pathway is through an abiotic reduction with humic acids （HAs）, which is controlled by different factors, including initial Hg and HA concentrations, pH, temperature and light. In this study, three humic acids were selected to illustrate the Hg2＋ abiotic reduction mechanisms by HAs, and to identify the key limiting factors for reduction rates and amounts. In addition, the initial status of the HAs as a solid or in an aqueous solution were also compared, to help explain why HAs show different dominant characteristics （e.g. complexation or reduction） in the reaction process with Hg. Results indicated that HAs were able to reduce Hg abiotically. Higher initial Hg, higher HA concentrations and either high （8.1） or low （3.6） solution pH decreased the HA reduction capacity. In addition, Hg~ production rates increased with increasing temperature, and the same trend was observed with light exposure. Humic acids added as an aqueous solution resulted in significantly greater HgO production than addition as a bulk solid. Finally, the Hg reduction rate and capacity varied significantly （P 〈 0.05） with HAs from different sources. These findings helped to explain why HAs showed different dominant characteristics （e.g. complexation or reduction） in the reaction process with of Hg2＋ reduction, which indicated that humic substances in sink or a source for Hg. Hg, and evidentially demonstrated the existence of a possible pathway natural environments, especially in water bodies, could act either as a
