| Radon(222Rn)is a radioactive noble gas,which exists in many living environment and workplace.It is one of the 19 kinds of carcinogenic substances announced by WHO.Lung cancer,leukemia,infertility,fetal malformations,genetic abnormalities and other diseases can be caused by high concentration of radon.Therefore,it is very important to detect radon in the environment.At present,there are two methods to detect radon,which are Applied Physics and Chemical measurement methods.Many environment factors affect the detection of radon so that to establish a simple operation,low cost,high sensitivity,stable and reliable results,small interference method for radiation dose detection of radon has a research significance.In the chapter 2,We established a novel method for detecting radon radiation dose based on daughter lead induced the conformational change of triple-helix molecular switch.In this study,radon decay form a stable daughter lead which collected by dilute acetic acid.We synthesized a triple-helix molecular switch aptasensor?THMS?.Established a new method for rapid,sensitive and simple detection of lead and radioactive radon gas.THMS has high selectivity and sensitivity to lead ion,It is very stable and retains the high affinity of original aptamer.In the absence of Pb2+,THMS is stable in solution,and the fluorescence intensity is weak after addition of G-quadruplex fluorescent dye NMM.When Pb2+exist in the solution,the Pb2+induce the conformational change of THMS to form G-quaruplex,and form a strong fluorescence with binding of NMM.The change of fluorescence intensity was positively correlated with the concentration of Pb2+,and the cumulative concentration of radon in the sample solution increased exponentially.The limit of detection is 1.20nmol/L and 302Bq·h/m3,respectively.The method avoids the radiation damage of radon during sampling,and opens up the dual detection of the radon and its daughters by the aptamer.In the chapter 3,A label-free fluorescence biosensor for detection of radon and lead based on Pb2+induced conformational change in aptamer133DNA was established.The single-stranded 133DNA did not bind to NMM so that the fluorescence intensity was weak.However,when the lead which decayed from radon was added.It induced 133 form a stable G-quadruplex.The interaction between G-quadruplex and NMM resulted in a sharp fluorescence signal change.The fluorescence intensity show a good linear relationship with lead ion and the radon concentration?D?.The limit of detection is 1.67nmol/L and 1.19×103Bq·h/m3,respectively.This sensitive method can exclude radiation damage when it detect radon and lead,it expands a new fluorescent sensors in the detect field for radioactive substances and gas.In the chapter 4,A new method based on lead ion induced conformational change of aptamer PW17 for fluorescence detection of radon was established.In this study,a label-free fluorescent biosensor was developed for the detection of lead and cumulative radiation dose.Daughter lead which decayed from radon was absorbed by dilute acetic acid to form lead ion.PW17 combined with thiazole orange?TO?can produce strong fluorescence.When Lead ion induce PW17 to form a chair G-quadruplex,the binding ability of G-quadruplex and TO dye was weakened,and fluorescence intensity decreased.Lead ion concentration between 5nmol/L and 90nmol/L,The fluorescence intensity decreased??F?showed a linear relationship with the concentration of lead ion,?F=1.28 cPb?nmol/L?+3.73,r=0.9964.Cumulative radon concentration between 1.5×104 and 9.0×104Bq·h/m3,?F=9.71c Rn-2.28,r=0.9926.The detection limit of lead ion is 2.88nmol/L,and the detection limit of radon is 707.5Bq·h/m3. |
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