The Preparation And Application Of Noble Metal Nanoclusters

Noble metal nanoclusters are relatively stable nanostructures consisting of two or more metal atoms.Due to their extraordinary physical properties and chemical properties,they have received extensive attention in the research community worldwide.Current metal nanoclusters have made significant advances in bioanalytical,bioimaging,therapeutic applications,DNA assembly and logic gate construction,enzyme simulation catalysis,and thermometers and pH meters.In addition,the construction of biologically functional noble metal nanoclusters for clinical diagnosis and treatment is also a great challenge in the future.In this dissertation,the synthesis of Ag NCs and Au NCs,assembly and application testing are the main research objects.The synthesis of noble metal nanoclusters using DNA as a template as a fluorescent probe has been explored.Experimental study mainly from the following three aspects to discuss the construction of fluorescent probe detection of biological macromolecules:(1)Preparation of silver nanoclusters and analysis and detection of DNA:Three-component sensing templates were constructed and stabilized by DNA-templated Ag NCs.The quenching group BHQ1 labeled DNA consists of a DNA scaffold that is complementary to the target DNA1 and target DNA2.The quenching group BHQ1 quenches near Ag NCs with fluorescence resonance energy transfer.The addition of target DNA will replace the fluorescent probes labeled with Ag NCs,and the fluorescence intensity will be significantly restored,enabling the qualitative and quantitative analysis of DNA.At the same time,according to the different adsorption capacity of graphene oxide(GO)on single-stranded DNA and double-stranded DNA,simultaneous determination of two target DNAs can be achieved.The fluorescence recovery of Ag NCs showed a good linear relationship with the concentration of target DNA1 within a certain range(0.33?6.25?M).The detection limit was 100 nM,and the concentration of target DNA2 was also within a certain range(0.33?7.41 ?M).)shows a good linear relationship with a detection limit of 76 nM.(2)Histone-enhanced silver nanoclusters fluorescence detection Pb2+:In the following experiments,we explored the effect of some proteins on the synthesis of Ag NCs and DNA template found that the combination of Histones and DNA can effectively increase the fluorescence intensity and prolong the fluorescence lifetime of Ag NCs.The fluorescence intensity can be effective.The increase to 250%,it's fluorescence intensity quenched with increasing Pb2+ concentration..Histone-DNA-Ag NCs correspond well to Pb2+ at 0.1 ?M?5?M with a detection limit as low as 1 nM.We speculate that the combination of histones and DNA may provide more stable and dispersed three-dimensional structures for Ag NCs.(3)Preparation of gold nanoclusters and analysis of exonuclease I:The DNA that consisting of repeated bases A and C uses as templates,the Au NCs with maximum fluorescence intensity was synthesized under the optimal number of bases.The max fluorescence peak of excitation and emission was 303 nm and 461 nm.According to the characteristics of Exo I,which can hydrolyze single-stranded DNA.After the addition of exonuclease I,the fluorescence intensity of Au NCs is reduced due to agglomeration.From the difference of fluorescence intensity can be simple,label-free detection of the concentration of exonuclease I.In a certain concentration range(0.05?0.35 ?M),showing a good linear relationship with a detection limit of 0.01 U mL-1.