Application Of Colorimetric Methods For Detection Of Inorganic Ions And Small Drugs On The Basis Of Triangular Silver Nanoplates

In present, nanoscience and nanotechnology have been applied in almost all fields of scientific research. The application of nanomaterials in analytical methods is one of the most popular hotspots in analytical chemistry. Triangular silver nanoplates (TSNPs), which have unique localized surface plasmon resonance (LSPR) properties, were selected for establishing novel colorimetric methods in this thesis. According to the reported methods, we synthesized a series of triangular silver nanoplates with different sizes, and studied by interacting with inorganic ions and drug molecules. We established a series new analytical methods based on triangular silver nanoplates. The mainly points of this thesis are as follows:1. We proposed spectrophotometric methods for detection of iodide ion, iodate ion and ascorbic acid on the basis of TSNPs. We synthesized different sizes of TSNPs and investigated the interaction between iodide ion and TSNPs. Experimental results showed that the TSNPs were fused to silver nanospheres by iodide ions, causing the disappearance of TSNPs’LSPR absorption. The color of TSNPs solution was changed to yellow. Thus, we can easily detect iodide ions by TSNPs using spectrophotometric methods or naked eyes. Furthermore, as we known, ascorbic acid can reduce iodate ion to iodide ion, so we can detect iodate and ascorbic acid indirect. Thus, we established UV-Vis spectrophotometric methods to detect iodide ion, iodate ion and ascorbic acid, and it also could be used for colorimetric detection by their color changes.2. In our further studies, we found that when different concentration of TSNPs solutions were used for TSNPs/I-interaction, the threshed concentration (c1) of I" for TSNPs completive transformation was also changed and shifted with the TSNPs concentration (cTSMPs), and a good relationship between TSNP concentration (cTSNPs) and I-threshed concentration (ct) can be established. On the basis of this phenomenon, a series of tubes containing different concentration of TSNPs were used for detecting an unknown I-sample. The color of tubes were changed from blue to yellow according to the concentration of TSNPs and unknown I-. The tubes with TSNPs concentration matched with the unknown I-concentration would show a threshed color, which could be distinguished easily by naked eyes. Thus, we could calculate the unknown I" concentration by TSNP concentration and their linear equation. This novel colorimetric method is sensitive, accurate and has wide range of detection concentration. Iodide ion with the concentration range from1×108to1×10-6M can be accurately detected by naked eyes, with relative error less than5%. Furthermore, this colorimetric method has good stability and repeatability, which need not to control nanoplate’s synthesis process and detection time exactly.3. We investigated the interaction of TSNPs with mercury ion. The absorption of TSNPs was blue shifted and decreased linearly at lower mercury ion concentration. However, at higher mercury ion concentration, the absorption of TSNPs decreased greatly with sligth red shifts. This is mainly due to the different states of the silver amalgam. According to the above phenomena, we established UV-Vis spectrometry to detect mercury ion.4. We established a simple spectrophotometric method for detection of ascorbic acid using bovine serum albumin protected-silver nanoclusters (BSA-AgNCs). Due to the catalysis effect of BSA-AgNCs, ascrobic acid can reduce Ag+to Ag0, producing silver nanoparticles (NPs) in BSA-AgNCs solution. A strong absorption band near420 nm presented in the mixture absorption spectrum, and the absorbance at420nm had good relationship with ascorbic acid concentration. The color of the mixture was changed from colorless to yellow and deep yellow, depending on the ascrobic acid concentration added. Thus, we proposed a spectrophotometric method to determine the ascorbic acid with concentration range from2.0μM to50.0μM.In conclusion, we investigated the interaction between triangular silver nanoplates (TSNPs) and kinds of inorganic ions and small drugs and established a series of spectrophotometric and colorimetric methods for detection of these inorganic ions and small drugs. In addition, we developed a colorimetric method to detect ascorbic acid by formation of silver NPs on the catalysis effect of BSA-AgNCs. We believe that all these new analytical methods will have good values in practical use.