The New Detection Methods For Lead And Radon Radiation Dose Based On Functional Nucleic Acids

Radon(222Rn)is the only gas radioactive elements,is the main form of indoor air pollutant.Radioactive elements uranium,radium,thorium and other decay produce radon,uranium-containing coal combustion and coal ash piling also produce radon.Radon in the indoor environment,mainly come from building materials,decoration materials,household water consumption and chemical fuel diffusion medium,exists in the human life and working environment,endanger the health of the people.Radon is the main physical pollutant monitored in the air environment.Radon radiates ?,?-rays and decays into stable 210 Pb.Physical methods are widely used to measure the radiation dose of radon by measuring the intensity of ? and ? rays.Based on the development of modern biological detection of lead and lead ions in radon progeny,three specific nucleic acids were induced to change in conformation by lead ion,and a sensitive method for the detection of lead was established.Three new methods can be used to detect the radiation dose of radon accurately.In chapter 2 of this paper,a new method for detection of lead and radon radiation dose based on unmodified gold-DNAzyme amplification technology was studied.Radioactive radon decays into a stable daughter product,which was used as the detection target to determine the radon radiation dose in a new technique.Pb2+ triggers DNAzyme to cleave a molecular beacon(MB),resulting in the stem–loop structure opening and forming two single DNA strands(ss DNA).The ss DNA binds to unmodified gold nanoparticles and effectively prevents their aggregation in a salt solution.The detached enzyme strands continue to complement the remaining MB to amplify the response signal.The detection limit of lead and radon were 2.01×10-10mol/L and 186.48 Bq·h/m3,respectively.The detection limit meets the national standard in China.The method is simple to operate and no pretreatment is required after sample collection.In chapter 3 of this paper,according to the characteristics of radon radioactive decay,a fluorescent sensor was established based on the daughter lead induced G-rich aptamer T30695 form G-quadruplex.When there was no lead in the system,T30695 will combine with its complementary chain to form a double-stranded DNA structure,and the fluorescent signal of NMM is weak.When the system contains daughter lead,aptamer T30695 can be induced to G-quadruplex structure and NMM combined with G-quadruplex structure produce strong fluorescence.The detection limit of lead and radon were 1.54×10-9mol/L and 1.07×104Bq·h/m3,respectively.In practice,the radiation hazard of radon radiation dose is avoided.In the chapter 4,Lead ions are used as detection object.Choose a classic G-rich oligonucleotide sequence PW17 to set up a label-free DNA sensor in the research of radioactive gas radon detection.The PW17 was induced by lead to forming G-quadruplex structure,which avoiding forming a double chain structure with the complementary chain C-PW17,resulting the resonance light scattering signal of PFP is enhanced in the system.The method is simple and easy to operate,almost has no interference and has high sensitivity.The detection limit of lead and radon were 1.93×10-9mol/L and 6.40×103 Bq·h/m3,respectively.