Research Of An Analysis Platform Based On Nucleic Acid Templated Nanoclusters

Nobel metal nanoclusters?NCs?are composed of several to about one hundred atoms and have received considerable research interest due to their ultra small particle size,good biocompatibility,low toxicity,and unique physical and chemical properties.Thus it shows a broad application prospects in disease diagnosis,cell imaging,biological tracer,environment detection,biological sensor.In comparison to the AuNCs and AgNCs,Its performance is similar but the precursor of CuNCs is cheaper,The research of copper nanoclusters fluorescence probe has attracted tremendous attention in recent years.DNA enzyme has a good performance in cutting connecting and modifing itself.Whic can only separated by exponential enrichment of systematic technology.Combing with unique optical properties of nanomaterials,newfluorescent,color,surface enhanced Raman spectroscopy,electrochemical and biological sensors will be developed.Based on poly T single-stranded DNA templated copper nanoclusters and DNA enzyme-cyclodextrin stable fluorescence system,We constructed an fluorescence analysis testing platform for metal ions.Our research content is as follows:In Chapter 2,a rapid sensitive fluorescent sensor has been developed for Hg???ions detection based on the specific thymine-Hg²⁺-thymine structure and photoluminescent property of DNA copper nanoclusters.Upon addition of Hg²⁺,poly thymine single strand DNA?P1?is transformed into double strand DNA through the formation of T-Hg²⁺-T configuration.Sodium ascorbate is effective to reduce Cu²⁺ to Cu0,and this reduction process is accompanied by formation of intermediate Cu+.However,Cu+ has an strong binding site within hydrogen-bonding moieties in the helix of dsDNA which facilating Cu0 gathered in dsDNA to form stronger fluorescent copper nanoclusters than ssDNA copper nanoclusters,and these changes in fluorescence intensity of DNA-Cu NCs are allowed for sensitive analysis of Hg???ions.Satisfactory linear relationship and detection limit were obtained.The resulting calibration plots exhibited good linear correlations in the range from 1.0 nmol·L^-1 to 10 ?mol·L^-1 for Hg???ions,and the detection limits of Hg???ions was 0.383 nmol·L^-1.The recovery was found to vary from 97.2%-106.6%.The proposed method was highly selective and other metal ions have no interfering effects on the determination.Moreover,satisfactory results were obtained while the proposed method was applied to determination of Hg²⁺ in real lake samples.In chapter 3,we still take the poly T single-strand DNA template copper nanoclusters as the research object,the experimental results show that the lead ion has an fluorescence quenching effect on ssDNA-CuNCs.We use ascorbic acid as reducing agent,then copper atoms gathered on the DNA molecular forming copper nanoclusters,which produce fluorescent signal.When added Pb²⁺ ion,Pb²⁺ and reducing intermediates Cu+ has an metallophilic interaction,Cu+ can not exsist surround in DNA molecular,The Cu+ disproportionation reaction product copper atoms can not attach in the DNA molecular too,which generate the fluorescent off.based on this,we design a lead ion mediated single-strand DNA-CuNCs fluorescence weakened sensing method,the fluorescence intensity decreased when added lead ions.Satisfactory liner relationship were obtained.The resulting calibration plots exhibited good liner correlations in the range from 10 nmol·L^-1 to 5 mmol·L^-1 for Pb???ions.The detection limits of Pb???ions was 4 nmol·L^-1,The recovery was found to vary from 97.8%-105.5%.This proposed method was applied to detect Pb²⁺ in real lake samples,it has potential application value in the environmental monitoring.In chapter 4,Using the cavity structure of cyclodextrin,DNA molecules and cyclodextrin form host-guest inclusion compound by solubilization and inclusion,which enhance the stability of the system performance.we design a sensing system based on DNA ribozymes-cyclodextrin,the system of the fluorescent intensity have changed owing to the shear specificity of the copper ions on DNA ribozymes,The resulting calibration plots exhibited good liner correlations in the range from 10 nmol·L^-1 to 200 ?mol·L^-1 for copper ions.The detection limits of copper ions was 6.54 nmol·L^-1,once added cyclodextrins,The resulting calibration plots exhibited good liner correlations in the range from 10 nmol·L^-1 to 10 ?mol·L^-1 for copper ions.The detection limits of copper ions was 4.87 nmol·L^-1,The fluorescence intensity is more stable than before.thus the improved copper nuclear DNA enzyme sensor of copper ion is simple,rapid and sensitive detection.