以壳聚糖为碳源通过水热法合成碳点, 对影响碳点荧光强度的水热温度、水热时间和壳聚糖质量分数进行考察。通过紫外分光光度计、荧光分光光度计、原子力显微、Fourier红外光谱仪、X-ray光电子能谱、X射线衍射仪对壳聚糖碳点的光学性质、化学结构、晶体结构、形貌结构等进行表征分析。结果表明, 在水热温度200 ℃、水热时间9 h、壳聚糖质量分数2%的条件下制备得到的壳聚糖碳点量子产率为32.86%。碳点呈现出主要尺寸为3～10 nm的球形颗粒状, 且在波长335 nm激发下, 发射峰位于410 nm（蓝)。对金属离子的选择性研究分析表明, Fe3+对碳点溶液的荧光猝灭效应最显著, 说明碳点对Fe3+具有较好敏感性和高选择性, 且荧光猝灭效率对Fe3+浓度在0～100 μmol/L范围内呈现线性响应, 因此有望将碳点作为荧光探针应用于Fe3+的检测表征。

In this study, carbon dots(CDs) were synthesized by hydrothermal method using chitosan(CTs) as carbon source. The influences of hydrothermal temperature, hydrothermal time and chitosan mass fraction on the fluorescence intensity of carbon dots were investigated. The optical properties, chemical structure, crystal structure, and morphology of CDs were characterized by using ultraviolet spectrophotometer(UV-vis), fluorescence spectrophotometer, atomic force microscope(AFM), Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS) and X-ray diffractometer(XRD). The results showed that the quantum yield of CDs was 32.86% at a hydrothermal temperature of 200 ℃, a hydrothermal time of 9 h and a chitosan mass fraction of 2%. The carbon dots show a spherical shape with a main size of 3 to 10 nm. When the carbon dots excited at a wavelength of 335 nm, the emission peak is located at 410 nm and presents blue light. The selective analysis of metal ions shows that the fluorescence quenching effect of Fe3+ on the CDs is the most significant, indicating that the carbon dots have good sensitivity and high selectivity for Fe3+. The fluorescence quenching efficiency exhibits a linear response when Fe3+ concentration in the range of 0～100 μmol/L, which makes it possible to use the carbon dots as a fluorescent probe for the detection and characterization of Fe3+.