The Study Of The Synthesization, Fluorescence And Toxicity Of Fluorescent Gold Nanoparticles

We categorise nanomaterial as those which has structured components with at least one dimension less than 100nm.It has many particular characterizations,such as volume effect,surface effect,and quantum size effect,macroscopical quanta tunnel effect and so on because of its physical and chemical performances different from nubbly solid.Many researches have focused on its application in crossed subject such as bio-medical field.Gold nanoparticles are a kind of nomal nanomaterial and can quench many fluorescent reagents.In the thesis a new method to synthesize fluorescent gold nanoparticles is report.Fluorescent gold nanoparticles have high fluorescent quantum yield.They are high water soluble and very stable for more than 1 year.The quenching effect of Ni²⁺on bovine serum albumin protected fluorescent gold nanoparticles(BSA-GNPs)is reported.The quenching mechanism is discussed and a static quenching mechanism was proposed. The number of binding sites(n),apparent stability constants(K)and corresponding thermodynamic parameters of BSA-GNPs-Ni²⁺complex are measured at different temperatures.We report a new method to investigate and evaluate the biotoxicity of BSA-protected gold nanoparticles(BSA-GNPs) and carbon nanotubes(CNTs)by luminescent bacteria.50%effective concentrations(EC₅₀)of BSA-GNPs and four CNTs with different diameters are determined.The thesis is divided into two parts.Part one describes property,synthesis methods and application of gold nanoparticles and carbon nanotubes in detail and reviews recent study of biological effects of nanomaterials in recent years.Part two includes three aspects.The first aspect describes a new method of synthesis of fluorescent gold nanoparticles.Fluorescent gold nanoparticles with-high quantum yield can be obtainded by a simple method.The second ascept describes quenching effect of nickel ions on fluorescent gold nanoparticles and the quenching mechanism was investigated in details.The third ascept describes application of luminescent bacteria for investigating biotoxicity of BSA-protected gold nanoparticles and carbon nanotubes. 1.Photoluminescence from water-soluble BSA-protected gold nanoparticlesThe photoluminescence from water-soluble gold nanoparticles,each composed of a 5.1 nm gold core and a bovine serum albumin(BSA)-protected layer,has been observed.The maximal excitation and the maximal emission,wavelength are at 320 and 404 nm,respectively.The photoluminescence quantum yield is estimated as 0.053±0.0070(or 0.065±0.0050),at room temperature.The mechanism of the luminescence is hypothesized to be associated with interband transitions between the filled 5d¹⁰band and 6(sp)¹ conduction band.The photoluminescence is sensitive to pH,organic solvents and metal ions.These observations suggest that this nanoparticles is a viable alternative to organic fluorophores or semiconductor nanoparticles for biological labeling and imaging.2.Quenching effect of nickel ions on fluorescent gold nanoparticlesThe quenching effect of Ni²⁺on bovine serum albumin protected fluorescent gold nanoparticles (BSA-GNPs)is reported.The quenching mechanism is discussed and a static quenching mechanism was proposed.The number of binding sites(n),apparent stability constants(K)and corresponding thermodynamic parameters of BSA-GNPs-Ni²⁺Complex are measured at different temperatures. Under optimum conditions,the fluorescence intensity of BSA-GNPs is linearly proportional to nickel concentration from 6.0×10^-8mol/L to 8.0×10^-6mol/L with a detection limit of 1.0×10^-8mol/L. The result indicated that BSA-GNP is a potential Ni²⁺probe.3.Investigating biotoxicity of BSA-protected gold nanoparticles and carbon nanotubes by luminescent bacteriaWe report a new method to investigate and evaluate the biotoxicity of BSA-protected gold nanoparticles(BSA-GNPs)and carbon nanotubes(CNTs)by luminescent bacteria.50%effective concentrations(EC₅₀)of BSA-GNPs and four CNTs with different diameters are determined.The EC₅₀of five kinds of nanomaterials were obtained,EC₅₀of BSA-GNPs is 26μM,EC₅₀of SWNT, (OD 1～2nm)is 33 mg/L,EC₅₀of MWNT(OD＜8nm)is 50mg/L,EC₅₀of MWNT(OD 20～30nm)is 54mg/L,EC₅₀of MWNT(OD＞50nm)is 84mg/L.The results show that the acute toxicity of CNTs is inverse proportion to their diameters.SEM and TEM images showed that the toxicity can be partly due to the physical damage.We hope to establish a simple,fast and sensitive method to detect biotoxicity of BSA-GNPs and CNTs.