Highly Selective Fluorescence Sensing of Mercury Ions over a Broad Concentration Range Based on Mixed Polymeric Micelles
详细信息 查看全文
- 作者：Jinming Hu ; Tao Wu ; Guoqing Zhang ; Shiyong Liu
- 刊名：Macromolecules
- 出版年：2012
- 出版时间：May 8, 2012
- 年：2012
- 卷：45
- 期：9
- 页码：3939-3947
- 全文大小：575K
- 年卷期：v.45,no.9(May 8, 2012)
- ISSN：1520-5835
文摘
We report on the fabrication of a new type of polymeric fluorescent Hg2+ probe covering a broad effective concentration range from nanomolar to micromolar levels and exhibiting considerably enhanced detection selectivity. Two amphiphilic diblock copolymers colabeled with Hg2+-reactive caged dye (RhBHA) and Hg2+-catalyzed caged fluorophore (HCMA) in the hydrophilic segments, PS-b-P(DMA-co-HCMA) and PS-b-P(DMA-co-RhBHA), were synthesized via sequential reversible addition鈥揻ragmentation chain transfer (RAFT) polymerization, where PS, DMA, HCMA, and RhBHA are polystyrene, N,N-dimethylacrylamide, hydrazone-caged coumarin, and rhodamine B (RhB) derivatives, respectively. The two amphiphilic diblock copolymers can spontaneously self-assemble into mixed micelles in aqueous solution possessing hydrophobic PS cores and HCMA and RhBHA moieties colabeled hydrophilic PDMA coronas. Fluorescence emissions of caged RhBHA and HCMA moieties can effectively turn on in the presence of low and high Hg2+ concentrations via Hg2+-induced ring-opening reaction and Hg2+-catalyzed hydrolysis mechanisms, respectively. The drastically different, but self-complementary reaction kinetics and optimum working concentration ranges of RhBHA and HCMA moieties endow the sensing system with high selectivity and broad sensing concentration range (from nanomolar to micromolar). In addition, the Hg2+-sensing platform can be further employed for the fluorescent ratiometric detection of Cu2+ ion via its selective quenching of the emission of acyclic RhBHA moieties. This work presents a new example of ensembling two partially selective chemical reaction-based fluorometric sensing motifs to achieve enhanced metal ion sensing selectivity and broadened working concentration ranges, which can be further generalized for the construction of other highly selective and broad dynamic range sensing systems.