单分散键合型含铕聚苯乙烯微球的制备与荧光传感性能

制备了一种可定性定量检测水溶液中三价铁离子的含铕聚苯乙烯微球, 分别用固体核磁碳谱(¹³C CP/MAS NMR)、 傅里叶变换红外光谱(FTIR)、 X射线光电子能谱(XPS)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 元素分析、 粒度分析和ζ电位分析等对其化学组成和结构形貌进行表征. 当铕配合物单体用量低于2.5%时, 可以得到稳定的单分散键合型含铕聚苯乙烯微球. 用紫外光激发时, 该含铕聚苯乙烯微球发射铕离子的特征红光. Fe³⁺能猝灭该微球的荧光, 酸根离子和其它金属离子对其干扰较少; 猝灭效率与Fe³⁺浓度在0~300 μmol/L浓度范围内均呈线性关系; 随着铕配合物单体用量的增加, 微球的荧光增强, 其在检测Fe³⁺的荧光时, 猝灭常数(K_SV)增加, 检测限(LOD)下降. 调节铕配合物单体的用量, 可获得热性能优异、 红光发射强度高且稳定性好的单分散聚苯乙烯荧光微球, 对Fe³⁺荧光检测显示出较高的选择性, 在生物检测和环境保护等领域具有较高的应用价值.

Preparation and Sensing Properties of Covalent-linked Europium Complex Monodisperse Polystyrene Microspheres†

Covalent-linked Eu-complex monodisperse polystyrene microspheres were prepared by a simple environment-friendly one-step soap-free emulsion polymerization. Styrene(St), Eu-complex monomerEu(AA)₃Phen] and methacrylic acid(MAA) were separately selected as matric monomer, fluorescent monomer, and water-soluble monomer. Meanwhile, Eu-complex monomer was also acted as cross-linked monomer. The chemical composition and morphology of the copolymer microspheres were characterized by ¹³C CP/MAS NMR, Fourier transform infrared spectrophotometer(FTIR), X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM), transmission electron microscope(TEM), particle size analysis and zeta potential analysis. With the increase of Eu-complex content, the stability of the emulsion decreased, and the particle size and its distribution of the polystyrene microspheres increased; meanwhile, the thermal stability of the polystyrene microspheres was also decreased. Through regulating Eu-complex monomer content(0.25%—2.5%, mass fraction), the polystyrene microspheres feature a stable spherical morphology with a narrow size distribution. Excited by ultraviolet light, the polystyrene microspheres can emit the characteristic red light of europium ion. The luminescence of the polystyrene microspheres originates mainly from the sensitization of ligands to europium ions, that is, the energy transfer from ligands to europium ions. Due to the strong binding ability of Fe³⁺ to N and O atoms, the coordination structure of Eu-complex has changed after adding iron ions. As a result, the luminescence of the polystyrene microspheres can be quenched by Fe³⁺, and the common anions and other metal ions have little interference. The quenching efficiency are linearly related to the concentration of Fe³⁺ ranged from 0 to 300 μmol/L. With the increase of the content of the europium complex monomer, the fluorescence intensity of the polystyrene microspheres is enhanced, and the fluorescence detection K_SV of Fe³⁺ is increased, while limit of determent(LOD) is decreased. Regulating the content of the europium complex, the monodisperse copolymer fluorescent microspheres exhibit excellent thermal stability, strong red light emission, and high selectivity for Fe³⁺ fluorescence detection, which have high application value in biological detection and environmental protection.