title: Ultrasensitive detection of uranyl by graphene oxide-based background reduction and RCDzyme-based enzyme strand recycling signal amplification.
abstract: We proposed a novel strategy which combines graphene oxide-based background reduction with RCDzyme-based enzyme strand recycling amplification for ultrahigh sensitive detection of uranyl. The RCDzyme is designed to contain a guanine (G)-rich sequence that replaces the partial sequence in an uranyl-specific DNAzyme. This multifunctional probe can act as the target recognition element, DNAzyme and the primer of signal amplification. The presence of UO2(2+) can induce the cleavage of the substrate strands in RCDzyme. Then, each released enzyme strand can hybridize with another substrate strands to trigger many cycles of the cleavage by binding uranyl, leading to the formation of more G-quadruplexes by split guanine-rich oligonucleotide fragments. The resulting G-quadruplexes could bind to N-methyl-mesoporphyrin IX (NMM), causing an amplified detection signal for the target uranyl. Next, graphene oxide-based background reduction strategy was further employed for adsorbing free ssDNA and NMM, thereby providing a proximalis zero-background signal. The combination of RCDzyme signal amplification and proximalis zero-background signal remarkably improves the sensitivity of this method, achieving a dynamic range of two orders of magnitude and giving a detection limit down to 86 pM, which is much lower than those of related literature reports. These achievements might be helpful in the design of highly sensitive analytical platform for wide applications in environmental and biomedical fields.
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Li
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China. Electronic address: yongsheng.w@tom.com.
authors.forename: Yong-Sheng
authors.initials: YS
authors.lastname: Wang
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China.
authors.forename: Jin-Xiu
authors.initials: JX
authors.lastname: Cao
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China.
authors.forename: Si-Han
authors.initials: SH
authors.lastname: Chen
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China.
authors.forename: Xian
authors.initials: X
authors.lastname: Tang
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China.
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Wang
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China.
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Zhu
authors.affiliation: College of Public Health, University of South China, Hengyang 421001, PR China.
authors.forename: Yan-Qin
authors.initials: YQ
authors.lastname: Huang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D021881:DNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D004785:Environmental Pollutants / Q000032:analysis*; D054856:G-Quadruplexes; D006108:Graphite / Q000737:chemistry*; D057230:Limit of Detection; D008652:Mesoporphyrins / Q000378:metabolism; D021141:Nucleic Acid Amplification Techniques; D010087:Oxides / Q000737:chemistry; D012313:RNA / Q000378:metabolism; D017974:Uranium Compounds / Q000032:analysis*
chemical_list: D021881:DNA, Catalytic; D004277:DNA, Single-Stranded; D004785:Environmental Pollutants; D008652:Mesoporphyrins; D010087:Oxides; D017974:Uranium Compounds; C065420:N-methylmesoporphyrin IX; D012313:RNA; D006108:Graphite
keywords: Enzyme strand recycling amplification; G-quadruplexes; Graphene oxide; N-methyl- mesoporphyrin IX; RNA-cleaving chimera DNAzyme; Zero-background signal