中文摘要：

硅量子点因其极佳的亲生物性和光学性能成为纳米材料新宠,但传统硅量子点水溶性差限制了它的广泛应用。本实验以三甲基硅咪唑为硅前驱体采用水热法制备水溶性咪唑基硅量子点。相对于硼氢化钠、抗坏血酸、牛血清蛋白、半胱氨酸和柠檬酸,柠檬酸钠作为还原剂和稳定剂制得的硅量子点荧光发射最强。合成反应于220℃下可在2 h内完成,所制备的硅量子点水溶性好,平均粒径为2.6 nm,红外分析证实其表面存在游离的咪唑基。研究表明,硅量子点能与铜离子相互作用导致荧光强度的明显下降。考察不同温度下Cu~（2＋）对硅量子点荧光的猝灭行为,发现荧光猝灭程度随温度升高而增大。这说明荧光下降属于静态猝灭,即Cu~（2＋）与硅量子点上的咪唑基作用形成稳定配合物。此外,共振光散射分析还揭示荧光猝灭过程伴随着粒子团聚。基于硅量子点的荧光猝灭行为,建立了痕量铜的荧光检测方法。当Cu~（2＋）浓度在0.04~2400μmol/L之间,硅量子点的荧光强度随Cu~（2＋）浓度的增加而线性下降,检出限（S/N=3）达1.29×10~（-8）mol/L。本方法具有高的灵敏度、选择性和重现性,已应用于果蔬中痕量铜的荧光检测。

英文摘要：

Silicon quantum dot has become an attractive nanomaterial due to their excellent biocompatibility and optical performance. However,poor water-solubility of the traditional silicon quantum dot limits its wide application. In this study,we reported the synthesis of water-soluble silicon quantum dots with imidazole groups by using hydrothermal method,in which N-trimethysilylimidazole was used as a precursor of silicon.Compared with sodium borohydride,ascorbic acid,bovine serum protein,cysteine and citric acid,the as-prepared silicon quantum dots offered the strongest fluorescence intensity when sodium citrate was used as the reducing agent and stabilizer for the synthesis. The reaction could complete within 2 h at 220℃. The obtained silicon quantum dots showed good water-solubility with an average particle size of 2. 6 nm,and the result of infrared spectroscopic analysis verified the existence of free imidazole groups on the surface. By means of the investigation of the fluorescence quenching behavior of copper ions towards the silicon quantum dots at different temperatures,we found that the degree of fluorescence quenching increased with the increase of temperature. There results proved that the fluorescence decrease belongs to static quenching. Namely,the interaction of Cu~（2＋）with imidazole groups on the surface of silicon quantum dots formed stable complex. In addition,the resonance light scattering analysis also showed that the fluorescence quenching process was accompanied by the agglomeration of particles. Based on the fluorescence quenching behavior of silicon quantum dots,we established a method for the fluorescent detection of Cu~（2＋）. When the concentration of Cu~（2＋）was in the range of 0. 04-2400 μmol / L,the fluorescence intensity would linearly decrease with the increase of Cu~（2＋）concentration,and the detection limit（ S / N = 3） reached 1. 29 ×10~（-8）mol / L. The method provided high sensitivity,selectivity and reproducibility,and was successfully applied to the det