The Stability And Reversible Aggregation Behavior Of DNA-Gold Nanoparticles Composite System

Owing to the unique properties in optics,electricity and magnetics,gold nanoparticles?AuNPs?have been widely applied in the fields of the environment,food,medicine,and so on.The simplest and most commonly used preparation route of AuNPs is the reduction of Au salt by sodium citrate under reflux.However,the prepared AuNPs are susceptible to aggregation at high ionic strengths or acidic conditions because of the changes in particles.Modifying the surfance of AuNPs with specific ligands is an effective approach for protecting against unselective particular aggregation.However,most of the reported methods present some disadvantages.CT-DNA has been extensively used in biomaterials and regeneratice medicine because of its biocompatibility,biodegradable and nontoxicity.In the persent study,DNA-AuNPs system with excellent stability was obtained using DNA to stabilize gold nanoparticles,which were prepared through citrate reduction method.The stability of DNA-AuNPs in buffer soulution with different p H conditions salt concentrations was systematically investigated,based on changes of color and the ultraviolet absorption peak.The main contents of this thesis are as follow:The stability of DN A-AuNPs in buffer solutions with different pH conditions was investigated by Ultraviolet-visible?UV-Vis?,Atomic force microscopy?AFM?,and transmission electron microscopy?TEM?.The results revealed that DN A afforded the AuNPs with remarkable stability in buffer solution of pH range 2-11.The solution was aggregatted when there is a large amount of H+ in the solution.The aggregation were not disappeared after the in the present o f O H-.The DN A-AuNPs had better advantage than AuNPs in the aspect of freeze-thawing.The stability of DN A-AuNPs in buffer solutions with different salt species and reversible aggregation were discussed based on changes of color and the ultraviolet absorption analysis.The result indicated that DNA afforded the AuN Ps with remarkable stability in different metal ion(0-300 ?L Na+,K+,Mg²⁺,N i²⁺).The solution were aggregatted when there is a large amount?300 ?L?of Fe³⁺ or Al3 + in the solution,the aggregation were disappeared in the presence of EDTA.