Determination Of Fe³⁺ And Al³⁺ In Food Using Fluorescence Spectrometry Methods Based On Bimolecular Protected Gold Nanoclusters

In recent years, food safety affairs occurred frequently, making food safety become a topical issue in current society. Specially, the food that was polluted by the heavy metal has a big threat for people health. Excess accumulation of metal ions in the body, may cause a series of diseases, seriously leading to death. Therefore, constructing a simple, efficient and accurate analysis method is of great significance to test the content of metal ions in food.Many methods have been applied for the analysis of metal ion content, such as paper method, colorimetric method, electrochemical method, atomic spectrometry, ultraviolet spectrophotometry-inductively coupled plasma spectrometry(ICP) and X-ray fluorescence spectrometry etc. Recently, the fluorescence spectrometry method which based on fluorescence gold-cluster has attracted great interest of the researchers. Gold nanocluster is a kind of nanomaterials with the size smaller than 2 nm. Compared to other nanomaterials, gold nanoclusters possessed unique molecular properties, optical properties, electrochemical properties, catalytic activity and other properties. Moreover, the biological molecules protected gold nanoclusters have many advantages, like low toxicity, low cost, strong fluorescence emission and bio-compatibility. Therefore, it is widely used in protein, polypeptide, biological small molecules, heavy metal analysis and biological imaging.In this thesis, we detect the mental content of food by using the fluorescence spectrometry based on bimolecular protected gold nanoclusters. The main results were shown as follows:1. In the work, L-histidine-stabilized gold nanoclusters were prepared by a green one-pot process. The obtained probe exhibited bluish green fluorescence, and exhibited an excitation maximum at 394 nm and emission maximum at 492 nm.2. The L-histidine-stabilized gold nanoclusters was employed as a selective probe for sensing ferric ions. The fluorescence of the probe was obviously quenched by adding ferric ions into the gold nanoclusters, indicating that the synthesized probe could be applied for sensing ferric ions. Further, we investigated the selectivity of the proposed probe for sensing ferric ions. The results declared that the fluorescent gold nanoclusters had favorable sensitivity and selectivity for the detection of ferric ions. Moreover, this probe was further used for the analysis of ferric ions in bean sprouts. It showed that the gold nanoclusters based fluorescent probe has great potential for sensing metal ions in plants.3. In the work, we synthesized GSH-stabilized gold nanoclusters by using a green onepot method. The obtained probe exhibited pale yellow fluorescence, and exhibited an emission maximum at 608 nm and excitation maximum at 370 nm.4. The fluorescence gold nanoclusters were used as the selective probe for sensing aluminium ions. When adding aluminium ions into the gold nanoclusters solution, its fluorescence was obviously enhanced, demonstrating that the synthesized probe could be used for sensing aluminium ions. Further, we studied the selectivity of the proposed probe for detecting aluminium ions. The results indicated that the fluorescent probe had favorable sensitivity and selectivity for the detection of aluminium ions. Moreover, this probe was further used for the analysis of aluminium ions in tea. It showed that the gold nanocluster based fluorescent probe has great potential for sensing metal ions in food.