Wireless Magnetoelastic Sensing Methods of Mercury (Ⅱ) and Uranyl Based on Functional Nucleic Acids
|Keywords||Wireless magnetoelastic sensor Functional nucleic acid Grapheneoxide Gold nanoparticle Uranyl Mercury(II)|
The pollution problem of heavy metal ion such as mercury （II） and uranyl hasbecome a global issue, even a trace amount of uranyl and mercury（II） can causetremendous toxic action. So it is very important to determine quantitatively uranyl andmercury（II）. The current techniques for uranium and mercury（II） detections havesome problems. For example, most of them involve tedious sample pretreatment, orrequire expensive instruments, and could not be carried out for in site detection ofuranium and mercury（II） and so on. In this thesis, we combine molecular recognitionand wireless sensing technology to build two new convenient, quick, real-time andsensitive methods, which are used for the detection of uranyl and mercury（II） inpractical samples. Furthermore, the interaction mechanism of FNA with uranyl ormercury（II） is studied to provide novel techniques, methods and experimentalevidences for the environmental monitoring and management, as well as themechanism investigation of toxic effect of uranyl and mercury（II）.In the chapter2, a wireless sensing method for uranyl detection based on specialDNAzyme and GO has been developed. Uranyl special DNAzyme can be assembledonto the AuNPs by the thiol （-SH） to form dsDNA-AuNPs complex. In the presenceof UO22+, the short ssDNA-AuNPs complex was released from DNAzyme, which isadsorbed to the surface of the sensor by π-stacking interactions for the first signalamplification in the MES buffer solution （pH5.0）. Then, in the presence of CTMAB,AuCl4–can be reduced catalytically by AA to atom Au coated on nanogold in big sizeon the surface of the sensor as the second signal amplification, resulting in aresonance frequency change of the sensor. Based on this principle, a wireless sensingmethod for the determination of UO22+was developed, and used in the analysis of practical samples. In the optimizing condition, a linear correlation existed between theΔf and the concentration of UO22+in the range of9.57×10-9～1.2×10-7mol·L-1. Theequation of linear regression was Δf=62.41c (×10-8mol·L-1)–7.30with a correlationcoefficient of r=0.9967. The limit of detection （LOD） was2.90×10-9mol·L-1. Theproposed method is rapid, sensitive and selective.In the chapter3, a novel wireless mothd for mercury（II） detection based on athymine-rich oligonucleotide （TRO）-Hg complex was established. A biotin labeledthymine-rich oligonucleotide was attached to streptavidin/AuNPs （AuNPs-SA） by ahigh specific affinity between the biotin and streptavidin to form dsDNA-biotin-SA-AuNPs complex. In a Britton-Robinson buffer solution of pH7.8, upon additionof Hg2+, the structure of the complex changed to form an T-Hg-T complex, and thereleased ssDNA-biotin-SA-AuNPs complex can be adsorbed to the surface the sensor,and cause the change of the resonance frequency. Based on this principle, a wirelessmethod for the determination of Hg2+was established. The equation of linearregression was Δf=24.31+103.4c(×10-7mol·L-1) with a correlation coefficient of r=0.9975. There is a linear relationship in the range of2.92×10-8～8.57×10-7mol·L-1with a limit of detection （LOD） of8.75×10-9mol·L-1. The proposed method is simple,rapid, sensitive and selective, and used for the determination of Hg2+in practicalsamples with a satisfactory result.