基于聚合物核壳纳米粒子的Hg~(2+)比率型荧光检测传感器

采用一步聚合的方法,制备了以疏水的聚甲基丙烯酸甲酯(PMMA)为核、亲水性的聚电解质支化聚乙烯亚胺(PEI)为壳的纳米粒子分散液.将供体荧光团4-胺基-7-硝基-N-辛基苯并1,2,5]噁二唑(NBD)以包埋的方式在聚合过程中直接引入PMMA核内部,而受体荧光团罗丹明衍生物SRHB通过吸附作用进入PEI-PMMA核壳界面,构成了含有两种不同荧光分子且可对Hg2+进行荧光比率检测的传感器.考察了含荧光分子的聚合物粒子光谱学性质,证明两种荧光分子均被引入了聚合物粒子体系.在汞离子的荧光检测试验中,加入Hg2+后,体系中的NBD荧光强度下降,而罗丹明的特征发射峰在579 nm处出现,并随着Hg2+浓度的增加,受体/供体的荧光强度比值呈现增长趋势.研究还发现,聚合物粒子基荧光探针对于Hg2+具有较好的选择性,且最佳使用范围是体系pH值在5～8之间,其检测Hg2+的最低浓度可达到1μmol/L.

CORE-SHELL POLYMER PARTICLES AS A FRET-BASED RATIOMETRIC SENSOR FOR MERCURY ION DETECTION IN WATER

A novel fluorescence resonance energy transfer(FRET)-based ratiometric sensor is reported for detecting Hg2+ in water.The polymeric nanoparticles were prepared by one-step polymerization of methyl methacrylate(MMA) and polyethyleneimine(PEI) using tert-butyl hydroperoxide(TBHP) as the initiator.For the nanoparticles,the hydrophilic polyethyleneimine(PEI) chain segments served as the shell and the hydrophobic copolymer of methyl methacrylate(MMA) and the cross-linker constituted the core of the nanoparticles.A hydrophobic fluorescent dye nitrobenzoxadiazolyl derivative(NBD) was embedded in the nanoparticles during the polymerization and used as the donor of the energy transfer process.A spirolactam rhodamine derivative SRHB was synthesized,and then introduced into the particles and used as an ion-recognition element.The presence of Hg2+ in the water dispersion of nanoparticles induced the ring-opening reaction of the spirolactam rhodamine moieties and led to the occurrence of the FRET process,affording the nanoparticle system a ratiometric sensor for Hg2+.The nanoparticle sensor can selectively detect the Hg2+ in water with the detection limit of 1×10-6 mol/L.Additionally,the FRET-based system exhibited large wavelength shift(ca.,150 nm) between the donor excitation peak(430 nm) and the acceptor emission peak(579 nm),which eliminates any influence of excitation backscattering effects on the fluorescence assay.It has been found that the FRET-based system with smaller nanoparticle as the scaffold exhibited higher energy transfer efficiency and was more preferred for the accurate ratiometric detection.This approach may provide a new strategy for ratiometric detection of analytes in environmental and biological applications.