Study On The Preparation Of Triangular Silver Nanoparticles And Its Application In Visual Detection

As a classical noble metal nanomaterial, silver triangular nanoplates (Ag TNPs) with unique shape and adjustable surface plasmon resonance (LSPR) properties, the changing of its size, shape, medium and space between particles will change its plasma spectral properties, which will cause the corresponding changes in the color of the sol. At present, Ag TNPs used as probes in colorimetric sensing system has attracted much attention. In this paper, homogeneous, stable Ag TNPs were prepared with clear edges and angles, the spectral characteristics of Ag TNPs were changed after reaction with the measured substance (chloride, ammonium and dopamine), and a series of photometric analytical methods were established. The mainly points of this thesis are as follows:1. Since the etching of Ag TNPs by chloride ion will change the optical properties of silver sol, we established a analytical method of chloride ion in water. Ag TNPs with different morphologies were prepared by adjusting the amount of reducing agent, and its interactions with the chloride were also studied. We found that Ag TNPs will be fused to spherical silver nanoparticles after contact with chloride ions, which lead to the localized surface plasmon resonance absorption peaks of Ag TNPs disappeared and produced spherical silver nanoparticles characteristic absorption peak. With the increasingof chloride ion, the color of nano silver sol gradually changed from blue to yellow.nanometer silver colloid color gradually changed from blue to yellow. Based on the above phenomenon, UV-Vis spectrophotometric method was established for the detection of trace chloride ion. The recoveries of spiked samples ranged from 95.41%to 106.67% with relative standard deviation (RSD) less than 5.43%.2. We investigated the interaction of Ag TNPs with ammonium persulfate and developed a analytical method for the detection of trace ammonium persulfate in water based adhesive for cigarette. The amount of Ag TNPs in sol were reduced because of the oxidization by ammonium persulfate, and the characteristics of localized surface plasmon resonance of Ag TNPs changed correspondingly, the characteristic peak of the characteristic peak is decreased, and the color of the sol gradually changed from blue to colorless. Based on the above mechanism, we have established a new method for the detection of trace ammonium persulfate in water based adhesive for cigarette. The recoveries of spiked samples ranged from 94.4% to 105.8% with relative standard deviation (RSD) less than 5.6%.3. Ag TNPs with uniform size were prepared by light radiation and the surface was modified by melamine. Study found that with the addition of dopamine, the localized surface plasmon resonance absorption peak intensity of melamine modified Ag TNPs in 561 nm was increased and in 862 nm was decreased, and the color of the solution also changed from blue purple to blue. As a result, we establish a UV-vis absorption spectrophotometric method and colorimetric method for the detection of trace dopamine (DA) in human serum, and the calibration curve was obtained with a good linearity of DA concentration ranged from 0.05 to 10 μM. The recoveries of spiked samples ranged from 92.4% to 106.8% with relative standard deviation (RSD) less than 5.32%.