The Study On The Application Of Gold And Silver Nanoparticles In The Small Molecules Analysis And Heavy Metal Ions Determination

Owing to the unique optical properties, electrical properties, catalysis and so on, gold and silver nanoparticles have been widely applied in fields of metal ion, small molecules, DNA and protein detection. So, in this thesis, based on the optical properties of gold and silver nanoparticle, we investigate the application of nanoparticles in determination of small molecules and heavy metal ion in environment. The main contents are as follows:1,Silver nanoparticles (AgNPs) have been used for copper ion detection. The citrate coated AgNPs are easily gathered in the salt conditions, and the chitosan can protect the AgNPs against aggregation. When adding appropriate copper ion, the coordination occurs between chitosan and copper ion. which lead to the distance of AgNPs decreasing and induce the aggregation of AgNPs. On the basis of this, we present a sensitive method for copper ion detection. Copper ion in the range of 3.33-40μM could be selectively detected with the linear equation of△A =0.062+0.019ccu, the correlation coefficient (r) of 0.9952 and the limit of determination (LOD)of 0.01μM.2,The morphological change of silver nanoparticles (AgNPs) induced by iodine has been used for copper ion detection. Iodine can fuse AgNPs, and produce AgI. However, at acidity condition, copper and iodine ion would occur oxidation-reduction reaction and produce iodine, which would fuse AgNPs and make the morphological change of AgNPs. This process was investigated by UV-vis absorption spectra and scanning electron microscope (SEM). Based on this phenomenon, we develop a simple and fast method for copper ion detection.3,Gold nanoparticle have the big specific surface area and could absorb rhodamine 6G by electrostatic interaction, resulting in fluorescence quenching due to fluorescence resonance energy transfer (FRET) between rhodamine 6G and the gold nanoparticles. In acidity condition, the carboxyl groups of captopril capped gold nanoparticles and amino groups of melamine would form H-bonds, resulting in the aggregation of gold nanoparticles and the decrease of specific surface area. Then, rhodamine 6G were released from surface of gold nanoparticle and the fluorescence switched to turn-on.Upon this, a fluorescence determination of melamine is developed. In the optimum condition, melamine in the range of 0.032-4μg mL-1 could be selectively detected with the linear equation of (IF-IF0)/IF02.12+4.58cmelamine, the correlation coefficient (r) of 0.9908 and the limit of determination (LOD) of 5.18ng mL-1.