| Radon is a colorless,tasteless radioactive gas generated by the decay of radium,widely exists in people's life and work place,mainly from stratum and construction,decoration materials,water,fuel,etc.When breathing enters the body will cause damage to the respiratory system,hematopoietic system and human organs,is confirmed as one of19 carcinogenic substances,the second cause of lung cancer.So,the rapid and sensitive detection of radon has very important significance.At present,there are many methods of radon measurement,mainly according to the ray and electron capture method.The experimental operation is complex,the instrument is expensive,and the experimental personnel have the harm of radiation damage.Therefore,it is very important to establish a simple,accurate and sensitive method for the detection of radon radiation.In the chapter 2,a new colorimetric method for radon is established based on Pb2+induce the conformational change of K+-stabilized G-quadruplex to form more stable structure Pb2+-stabilized G-quadruplex and the ability bind to hemin decreases,and inhibit the peroxidase-like activity.Under the certain conditions,K+can induce PS2.M to form stable G-quadruplex bind to hemin with peroxidase-like activity,catalyze the oxidation of TMB by H2O2,which results in a color change.Upon the addition ofPb2+,K+-stabilized PS2.M is induced to convert to the Pb2+-stabilized G-quadruplex with higher stability but lower DNAzyme activity,result in the color and absorbance change of the system.Pb2+concentration in the range of 5×10-91.8×10-7mol/L,there is a good linear relationship between?A and c Pb:?A=0.36+0.13c Pb??×10-8mol/Lr=0.9973,the detection limit is 3.76nmol/L.Radon concentration in the range of 7.1×1041.02×105Bq·h/m3,there is a good linear relationship between?A and c Rn:?A=0.59+0.089cRn?×104Bq·h/m3?,r=0.9916,the detection limit is 1.96×103 Bq·h/m3.This method is sensitive,accurate,simple and can be used for the detection of lead and radioactive gas radon in the environment.In the chapter 3,a new method was established for the determination of lead and the cumulative radiation dose of radon,which was a nucleic acid aptamer non marking fluorescence method.Thioflavine T could induces G rich nucleic acid sequence 9-3-35 to form stable conformation G-quadruplex structure,which leads to fluorescence.The lead ion maked the G-quadruplex more stable and the fluorescence intensity was further enhanced.Radon decay can produce stable daughter lead.And radon sample solution had the same effect of lead ion.When the concentration of lead ion was cPb=1.0125.0nmol/L or cRn=3.0×1042.2×105 Bq·h/m3,The fluorescence change value??F?with cPb or cRn showed a good linear relationship,?F=9.13 cPb+163.40,r=0.9953,and?F=35.59cRn+229.51,r=0.9940.The detection limit was 0.312nmol/L and 1.87×103Bq·h/m3,respectively.The method is simple,sensitive and easy to be popularized.It can be used for the detection of lead and radon,which provides a new method for the detection of radioactive hazards. |
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