Preparation Of Fluorescent Gold Nanoparticles Using Multi-Functional Polymer Ligands And Their Biological Application

At present, gold nanoparticles (Au NPs) have a great protential application such as target drug delivery, desease detection, molecular recognition, cell labeling, chemical catalysis and optoelectronic, due to their good stability, unique photoelectric effect and excellent biocompatibility. With the size decreasing, the surface energy of Au NPs increases, which lead to the agglomeration of the unstable Au NPs. The method of solving this problem is using stabilizer to protect and modify the Au NPs in order to decline the surface energy and control the size, morphology and properties of Au NPs.Compared to other traditional ligands, multi-functional thioether polymer ligands have enormous advantages, such as better stability and controllability, easy modification, easy ligand exchange and low toxicity. In this thesis, the oil-soluble and water-soluble multi-functional thioether polymer ligands were designed and synthesized, and by using these ligands to prepare Au NPs with small-sized, monodisperse, bio-compatible and unique physical properties, which are better than those prepared by traditional methods. The main contents are listed as follows.(1) Multi-functional thioether polymer ligands were designed and synthesized for preparing nearly-monodisperse, small-sized Au NPs and fluorescent gold nanoclusters (Au NCs).(2) An approach was proposed to produce fairly uniform Au NPs with diameters about 2-6 nm using oil-soluble multifunctional thioether polymer ligands (DDT-PVAc and PTMP-PVAc) as the capping agents, which could make up the backdraws of larger size and polydisperse.(3) A facile preparation of highly fluorescent Au NCs using oil-soluble multifunctional thioether polymer ligands PTMP-PVAc in homogeneous system without surfactant was reported. Homogeneous method does not need surfactant which can greatly simplify the post-treatment process. In addition, Au NCs with high fluorescent quantum yield of 27.3% will be applied in the field of optoelectronics.(4) Highly bright aqueous Au NCs were prepared by a facile one-step reduction method using water-soluble multidentate polymer PTMP-PMAA as ligands. The fluorescence quantum yield of resultant Au NCs is 4.8%, higher than the similar sized Au NCs prepared by etching approach. These Au NCs exhibit higher photostability than the standard rhodamine 6G.(5) The fluorescent water-soluble Au NCs have been successfully used as alternative biomarkers to label the hematopoietic system cells. The results demonstrated that cancer cells obviously uptake more Au NCs than normal cells. The cytotoxicity experiments confirmed that these Au NCs did not exhibit acute toxicity. These Au NCs thus show great potential applications in detection and treatment of cancers and other diseases due to their selective affinity to cancer cells, excellent near-infrared emission, high photostability, good biocompatibility and low cytotoxicity.