The Study On The Novel Methods For The Rapid And On-site Detection Of Uranyl Ion

Uranium is a radioactive element,trace uranium in the environment will not only directly harms human body,but also can be enriched by organism and affect human body indirectly via biologic chain.On-site and rapid detection of uranium is the most effective method to prevent uranium damage.So,the research on the rapid detection of uranium is of great significance.The main aim of this study is to develop raipd and on-site methods for detecting trace UO22+,in hope of providing a reliable and simple method for rapid and on-site detection of UO22+ in aqueous environment to ensure human health.The main contents includes:(1),A novel fluorescent biosensor for detecting UO22+ in aqueous environment has been developed based on the specific recognition of DNAzyme and the fluorescence quenching ability of molybdenum disulfide(MoS2)nanosheets.The DNAzyme contains a DNA enzyme strand and a 6-carboxy lfl uoresce i n(FAM)-labeled DNA substrate strand.We demonstrated that MoS2 nanosheets have low affinity to the substrate-enzyme complex DNAzyme.Whereas,in the presence of UO221,UO22+ can specifically cleave DNAzyme to release FAM-labeled single-strand DNA and the released FAM-labeled single-strand DNA can be firmly adsorbed on the surface of MOS2 nanosheets,which resulted in an obvious decrease of fluorescence intensity.This provided a sensing platform for the rapid,simple and sensitive fluorescent detection of UO22+.By using the sensing platform,a sensitive and selective fluorescent method for the rapid detection of UO22+ has been developed.In comparison with previous biosensor,the proposed method has obvious analytical advantage such as relatively high sensitivity and good stability,short analytical time and low cost.It can be used to detect as low as 2.14 nM of UO22+ in aqueous environment with a recovery of 96-102%and a RSD<5%(n = 6).The success of this study provides a promising alternative for the rapid and on-site detection of UO22+in environmental monitoring.(2),A novel visual method for detecting trace uranyl ion(UO22+)based on DNAzyme together with magnetic beads(MBs)-based separation and gold nano-particles(AuNPs)-based signal amplification was developed.The prepared method combined the merits of MBs,DNAzyme and horseradish peroxidase(HRP)catalytic oxidation of TMB/H2O2 system.It has outstanding analytical advantages including short analysis time,high sensitivity,excellent specificity and robust resistance to matrix.It can be used to deterIine UO22+ in environmental water sample with a detection limit of 0.02 ppb(77 pM)by the naked eyes observation and a detection limit of 7 pM by ultraviolet spectrophotometry.By using the proposed method,we have successfully determined trace UO22+ in water sample with a recovery of 93-99%and a RSD<6.0%(n=5).The success of the present biosensor served a new method for the rapid,on-site and visual detection of ultratrace UO22+ in environmental water sample.