An ultrasensitive electrochemical biosensor to detect trace Hg^(2+)in environmental samples was developed utilizing nanogold-decorated magnetic reduced graphene oxide(MrGO-AuNPs),exonuclease III-assisted target cycle(...An ultrasensitive electrochemical biosensor to detect trace Hg^(2+)in environmental samples was developed utilizing nanogold-decorated magnetic reduced graphene oxide(MrGO-AuNPs),exonuclease III-assisted target cycle(Exo Ⅲ-ATC)and hybridization chain reaction(HCR)synergistic triple signal amplification.The MrGO-AuNPs is a superior carrier for capture DNA(cDNA)and acts as magnetic media for automatic separation and adsorption.This innovative utilization of the magnetism and improved sensing efficiency obviates the need for direct modification and repeated polishing of the working electrode.Additionally,the three DNA hairpins(cDNA,methylene blue(MB)labeled HP1 and HP2)further contribute to biosensor specificity and selectivity.When cDNA captures Hgt,it activates Exo Ⅲ-ATC due to the formation of a sticky end in the DNA stem via thymine-Hig-thymidine(T-Hg^(2+)-T),this leads to the hydrolysis of self-folded DNA by Exo Ⅲ-ATC to form"key"DNA(kDNA).The kDNA subsequently initiates HCR,resulting in massive super-sandwich structures(kDNA-[HP1/HP2])carrying signaling molecules on MrGO-AuNPs,and this overall structure serves as a signal probe(SP).Leveraging magnetic adsorption,the SP was automatically adsorbed onto the magneto-glass carbon electrode(MGCE),generating an amplified signal.This biosensor's detection limit(LOD)was 3.14 pmol/L,far below the limit of 10 nmol/L for mercury in drinking water set by the US EPA.The biosensor also showed excellent selectivity when challenged by interfering ions,and the results of its application in actual samples indicate that it has good potential for practical applications in environmental monitoring.展开更多
基金This study was supported by the Key Research and Development Program of China(No.2018YFC0213400)the National Natural Science Foundation of China(Nos.21737002,21976119,and 22176126)。
文摘An ultrasensitive electrochemical biosensor to detect trace Hg^(2+)in environmental samples was developed utilizing nanogold-decorated magnetic reduced graphene oxide(MrGO-AuNPs),exonuclease III-assisted target cycle(Exo Ⅲ-ATC)and hybridization chain reaction(HCR)synergistic triple signal amplification.The MrGO-AuNPs is a superior carrier for capture DNA(cDNA)and acts as magnetic media for automatic separation and adsorption.This innovative utilization of the magnetism and improved sensing efficiency obviates the need for direct modification and repeated polishing of the working electrode.Additionally,the three DNA hairpins(cDNA,methylene blue(MB)labeled HP1 and HP2)further contribute to biosensor specificity and selectivity.When cDNA captures Hgt,it activates Exo Ⅲ-ATC due to the formation of a sticky end in the DNA stem via thymine-Hig-thymidine(T-Hg^(2+)-T),this leads to the hydrolysis of self-folded DNA by Exo Ⅲ-ATC to form"key"DNA(kDNA).The kDNA subsequently initiates HCR,resulting in massive super-sandwich structures(kDNA-[HP1/HP2])carrying signaling molecules on MrGO-AuNPs,and this overall structure serves as a signal probe(SP).Leveraging magnetic adsorption,the SP was automatically adsorbed onto the magneto-glass carbon electrode(MGCE),generating an amplified signal.This biosensor's detection limit(LOD)was 3.14 pmol/L,far below the limit of 10 nmol/L for mercury in drinking water set by the US EPA.The biosensor also showed excellent selectivity when challenged by interfering ions,and the results of its application in actual samples indicate that it has good potential for practical applications in environmental monitoring.
