| The pollution of water ecological environment is an extremely significant global issues own to the rapid development of economy and industry.It seriously threat to human health and the ecological environment.Thus,monitoring and controlling water pollution from its source is an essential method to effectively control water pollution.Aiming at the problems of poor interference resistance,long detection time,low sensitivity,and complex operation in current water pollution monitoring methods,herein,DNA nanomaterials have been designed and synthesized to construct DNA tracer detection platform with simple operation,high sensitivity,and strong interference resistance.The mainly works were carried out as follows:(1)Nucleic acid modified gold nanoparticles synthesis for colorimetric DNA tracer detectionIn this work,the nucleic acid sequences were designed by Integrated DNA Technologies software,which could effectively capture the tracer DNA.Then,sodium citrate reduction method was used to prepare gold nanoparticles,and nucleic acid was used to modify gold nanoparticles to obtain modified gold nanoparticles.A system for colorimetric DNA tracer detection based on modified gold nanoparticles was constructed.The factors affecting the detection system,such as the concentration of NaCl,reaction time,and the concentration of nucleic acid modified gold nanoparticles,were optimized.The sensitivity,selectivity,and interference resistance of the detection system were studied.The results showed that the optimal concentration of NaCl for the detection system was 250 m M,the optimal reaction time was 50 min,and the optimal concentration of nucleic acid modified gold nanoparticles was 1μM.The detection system had good selectivity and anti-interference.The linear range of the detection system for visual detection of DNA tracer was 10 n M to 100 n M,with a fitting equation of A=0.846log C-0.638,and a correlation coefficient of R~2=0.998.(2)A sensitive colorimetric system for DNA tracer detection based on toehold mediated strand displacement reaction and modified gold nanoparticlesOn the basis of the successful preparation of nucleic acid modified gold nanoparticles and the successful construction of its colorimetric detection system,in order to further improve the detection sensitivity,this work used a toehold mediated strand displacement reaction as amplification system.Firstly,the single stranded DNA sequence required for toehold mediated strand displacement reaction was designed by using Integrated DNA Technologies software.and a colorimetric detection system was built based on toehold mediated strand displacement reaction combined with gold nanoparticles.The synthesis conditions of the reaction substrate and toehold mediated strand displacement reaction were further optimized.Under the optimal conditions,the sensitivity of the detection system was studied.The detection system visually detected DNA tracer in the range of 0.1n M to 80 n M,with a fitting equation of A=(0.383-0.163 log C)/(1-0.481 log C),R~2=0.994.(3)Study on electrochemical detection of DNA tracer based on branched nucleic acidIn this work,branched DNA(Y1-DNA and Y2-DNA)was designed and synthesized,and the novel electrochemical detection platform based on Y2-DNA modified Au NPs was built to rapid and sensitive DNA tracer detection.A Y1-DNA and Y2-DNA modified gold nanoparticles were employed as probe and amplifier to specifically recognize the T-DNA and amplify the detection signal.Y1-DNA probe had more capturing points than single-stranded DNA,enhancing the capturing of T-DNA.The two strategies were both used to improve the sensitiveness of detection platform.The selectivity,sensitivity,interference,and recovery of the detection platform were systematically studied.The research results showed that the detection range of T-DNA by this detection platform was0.1 p M to 10 n M,the fitting equation was Y=-21.572+3.789 log C-0.410 log C~2,R~2=0.987.The limit of detection reached to 0.09 p M(S/N=3),and the three recoveries were 91.8%,97.3%,and 97.3%,respectively.The detection platform had good selectivity,anti-interference,and repeatability. |
