【摘要】 以海藻酸钠（SA）为碳源，引入邻苯二胺（oPDA）为助剂，采用一步水热合成法制备新型的氮掺杂碳化聚合物点SA-oPDA CPDs。该CPDs溶液在352 nm波长激发下，于462 nm处有蓝绿色荧光发射信号，stokes shift可达到110 nm,并显示出良好的光稳定性和激发波长不依赖性，荧光量子产率为16.9%。碳化聚合物点保留有海藻酸钠聚合链的特征，通过静电吸附组装技术，与壳聚糖形成复合发光薄膜，具有发光器件可应用潜力。该碳点水溶液对pH值极具敏感性，随着溶液环境由酸性变化到碱性，荧光强度增加的同时伴随着荧光发射峰位置从465 nm蓝移突变至425 nm,相应碳点的表面荷电状态由正电荷变化为负电荷。结构和形貌表征，在高温碳化过程中，该碳点内部形成碳化发光中心，外层表面共存来源于邻苯二胺和海藻酸钠的胺基和羧基。在溶液环境中，碳点的带电状态随溶液pH值的变化而变化，出现类似两性电解质的荷电性质，并在pH 6～7存在等电点。这可能是由于碳点表面羧基的解离和胺基的质子化的共同作用，并导致溶液表现出发光可调性。CPDs在pH 6.80的溶液环境下与铅离子结合后，溶液发射的荧光从蓝色变化为蓝绿色，可实现对一定浓度铅离子的明显可视化响应。研究表明还原性的药物对该碳点荧光信号有明显的猝灭效应。槲皮素对碳点的荧光猝灭程度在7.9×10^-6～7.7×10^-5 mol·L^-1浓度范围内，可呈现方程为I₀/I=0.878 8+1.689 7×10^-6c_Que的线性响应，相关系数r²=0.974 8,检出限LOD=1.7×10^-6 mol·L^-1。更多还原

【Abstract】 Novelty luminous carbonized polymer dots（CPDs） were synthesized by rapid and facile hydrothermal carbonization of sodium alginate（SA） and o-phenylenediamine（PDA）. The SA-oPDA CPDs reveal a large Stokes shift up to 110 nm under the excitation wavelength at 352 nm and emission wavelength at 462 nm. The synthetic CPDs exhibited bright blue fluorescence with a fluorescence quantum yield of 16.9% and excellent photostability and excitation wavelength independence. Just for the characteristics of the alginate polymerization chain, the SA-oPDA CPDs also demonstrated the practical feasibility of establishing the fluorescent films by self-assembled chitosan polyelectrolyte molecular with electrostatic adsorption. Thus, it has great potential application in light-emitting devices. Meanwhile, the SA-oPDA CPDs were found to have extraordinary amphoteric charge adjustability by pH value. With the change of solution environment from acidic to alkaline, the position of the fluorescence emission peak changed from 465 to 425 nm, and the surface charge of the carbon point changed from positive charge to negative charge. The structure and morphology characterization showed that during the high-temperature carbonization process, the polymer is carbonized to form a luminescent carbon core and contains hydroxyl, amine, and carboxyl on the surface of CPDs. Due to the active protonation/deprotonation of amino or carboxyl groups, the CPD solution exhibits luminescence tunability with pH alterations. The SA-oPDA CPDs exhibited an amphoteric nature with the isoelectric point between pH of 6 and 7, respectively. After the CPDs were combined with lead ions in the solution environment at pH 6.80, the fluorescence emitted by the solution changed from blue to blue-green, which could realize an obvious visual response to a certain concentration of lead ions. The experimental results also showed that the reduced drug, especially quercetin（Que）, had a significant quenching effect on the fluorescence signal of CPDs. The degree of fluorescence quenching had a good linear relationship with the concentration of quercetin in the range of 7.9×10^-6～7.7×10^-5 mol·L^-1. The equation was I₀/I=0.878 8+1.689 7×10^-6c_Que, correlation coefficient r²=0.974 8, and the LOD of detection was 1.7×10^-6 mol·L^-1.更多还原