Synthesis Of Fluorescent Noble Metal Nanoclusters Using Water-soluble Thiol-ending Polymer Ligands

Fluorescent metal nanoparticles(NPs) are of significant interest because of their small size and thus have the obviously different optoelectronics and other physical and chemical properties from their bulk metal materials, making them widely applied in biological detection, imaging and fluorescence labeling. Au and Ag NPs are the most popular because of their strong fluorescence, good stability and biocompatibility. In recent years, researchers have already developed various methods to synthesize the water-soluble fluorescent Au or Ag NPs. We need to further explore how to improve the quantum yield of the fluorescent NPs and to find the facile method for simple preparation of fluorescent NPs to make them applied as biomarkers.In this thesis, we prepared red fluorescent silver nanoparticles and gold nanoclusters by using the designed water-soluble polymer ligand PTMP-PMAA rich of thiol groups with chemical reduction and sonication method respectively. Fluorescence spectrum, X-ray photoelectron spectroscopy(XPS), energy dispersive X-ray analysis(EDAX) and other research methods were employed to characterize these metal NPs. The main contents are as follows:1. The highly fluorescent Ag NPs@PTMP-PMAA with the quantum yield up to 11.25% were synthesized by first preparing Au NCs@PTMP-PMAA with the chemical reduction method using NaBH4 as reductant, followed by the addition of silver nitrate(AgNO3) in which we regulate the amount of AgNO3 and the reaction time. We proved the fluorescence enhanced nanoparticles are silver NPs with various characterizations. This highly fluorescent Ag NPs are quite different from that prepared by the simple reduction of NaBH4.2. Red emission Au NCs@PTMP-PMAA with the quantum yield of 6.15% are synthesized by using ultrasonic reaction method in the absence of metal reducing agent. The obtained NCs have narrow size distribution and are quite stable in different metal ions solutions. We studied the effect of the polymer concentration, polymer molecular weight, sonication time, sonication power on the performance of the fluorescence intensity of the Au NCs in order to optimize the reaction conditions.