Preparation And Application Of Polyamine Functionalized Silver Nanoparticles

Metal nanoclusters are nanomaterials consist of several to hundreds metal atoms,they possess many excellent physical and/or chemical properties,such as small size,good solubility,excellent bleaching ability and low toxicity,and so on.As we all know,one of the most important factors for deciding the applications of metal nanoclusters is its stability;thus fabricating metal nanoclusters with high stability is one of the major interest on recent research.Compared with other metal nanoclusters,silver nanoclusters(AgNCs)have been widely used in analytical-realted fields because its unique optical properties and other characters including good stability,low toxicity,strong fluorescence and skillful preparation technology.At the past few decades,much attention has been paid to the construction of AgNCs-based sensor via the change of fluorescent intensity.Unfortunately,few researchers were focued on the performance of chemiluminiscence of AgNCs.In this thesis,we succeed in preparing AgNCs with high stability.Also,we found that reactive oxygen species(ROS)can induce the generation of CL from AgNCs.The detailed CL mechanism was investigatd.On the baise of this property,a CL approach for tea polyphenol(TPPs)detection was fabricated based on AgNCs.Moreover,ROS could also lead to changes of the fluorescence properties of AgNCs.In view of this phenomenon,AgNC-based fluorescent sensor was exploited for the detection of hydrogen peroxide(H2O2).(1)Hyperbrached poly ethyl eneimine functionalized AgNCs(hPEI-AgNCs)with high stability were synthesized by using hPEI as the template,AA as the reductant.Among the addition of six kinds of ROSs,only hydroxyl radical(·OH)could induce the production of CL from hPEI-AgNCs,while adding other ROSs including H2O2,singlet oxygen(1O2),superoxide anion(O2·-),ClO-and peroxynitrite(ONOO-)have no similar CL response.These results showed that hPEI-AgNCs may have selective CL toward OH.We proposed the CL mechanism and selective reason via electrochemical measurements and simulation.On the other hand,we set up a new method to detect the content of TPPs using hPEI-AgNCs-·OH system based on the excellent ability of ROS elimination of TPPs,which showed a low detect limitation(2.52 ?M).Also,this method displayed good selectivity,and the TPPs detection was not interfered by small molecules such as theanine,aspartic acid,histidine,xanthine or metal ions including Ca2+,K+.Using this method,estimation of TPPs content in tea samples infusion from different teas or immersion times was achieved.(2)The oxidition of hPEI-AgNCs induced by ·OH could also quench the fluorescence.On the basis of this phenomenon,we developed an hPEI-AgNCs-based fluorescent H202 detection method through integrating Fenton reaction,which can produce ·OH by mixing H2O2 and FeS04.After the optimization of several reaction parameters,including the hPEI-AgNCs concentration and FeS04 concentration,sensitive H2O2 detection with a detection limit of 0.16?M was realized.This method also displayed strong anti-jainmming capability,small organic molecules such as glucose,ascorbic acid,glutathione and sodium citrate,as well as the metal ions(e.g.,Ca2+ and Mg2+)or halogen anions have no influence on the determination.In addition,practical detection of H2O2 in real water samples was perfomed,and the results were consistent with previous reports,suggesting this method can be applied to environmental H2O2 monitoring.