We report on the fabrication of fluorescent and multicolor probes for Zn2+ ions and temperature from a mixture of three types of fluorophore-labeled responsive block copolymers in aqueous media. Quinoline-based Zn2+-r...We report on the fabrication of fluorescent and multicolor probes for Zn2+ ions and temperature from a mixture of three types of fluorophore-labeled responsive block copolymers in aqueous media. Quinoline-based Zn2+-recognizing fluorescent monomer ZQMA, red-emitting rhodamine B-based monomer RhBEA, and blue-emitting coumarin derivative Coum-OH, were synthesized first. A ZQMA-labeled well-defined double hydrophilic block copolymer(DHBC), PEG-b-P(MEO2MA-co-ZQMA), was synthesized via reversible addition-fragmentation chain-transfer(RAFT) polymerization of 2-(2-methoxyethoxy)ethyl methacrylate(MEO2MA) and ZQMA by utilizing a PEG-based macroRAFT agent. Following similar procedures, PEG-b-P(St-co-RhBEA) amphiphilic diblock copolymer and PEG-b-P(MEO2MA-co-Coum) DHBC were also synthesized, where P(St-co-RhBEA) was a RhBEA-labeled polystyrene(PS) block. At room temperature in aqueous solution, almost nonfluorescent PEG-b-P(MEO2MA-co-ZQMA) can effectively bind Zn2+ ions, leading to prominent green fluorescence enhancement due to the coordination of ZQMA with Zn2+ ions. However, by mixing red-emitting PEG-b-P(St-co-RhBEA) and blue-emitting PEG-b-P(MEO2MA-co-Coum) with PEG-b-P(MEO2MA-co-ZQMA) at an appropriate ratio, three color transitions could be observed. In the absence of Zn2+ ions, a mixed pink fluorescent originating from Coum and RhBEA was observed; upon the addition of a certain amount of Zn2+ ions, the green fluorescence enhanced dramatically, leading to a white fluorescence readout. By further increasing the amount of Zn2+ ions, the green fluorescence further enhanced and overwhelmed the blue and red emissions, leading to a green-dominant mixed-fluorescence emission. In addition, upon increasing the temperature, the fluorescence of Coum decreased considerably due to the fluorescence-resonance energy transfer(FRET) between Coum and ZQMA moieties. In this way, a ratiometric fluorescent thermometer can be constructed.展开更多
基金supported by the National Natural Science Foundation of China(21274137,51273190,91027026,and 51033005)the Specialized Research Fund for the Doctoral Program of Higher Education(20123402130010)
文摘We report on the fabrication of fluorescent and multicolor probes for Zn2+ ions and temperature from a mixture of three types of fluorophore-labeled responsive block copolymers in aqueous media. Quinoline-based Zn2+-recognizing fluorescent monomer ZQMA, red-emitting rhodamine B-based monomer RhBEA, and blue-emitting coumarin derivative Coum-OH, were synthesized first. A ZQMA-labeled well-defined double hydrophilic block copolymer(DHBC), PEG-b-P(MEO2MA-co-ZQMA), was synthesized via reversible addition-fragmentation chain-transfer(RAFT) polymerization of 2-(2-methoxyethoxy)ethyl methacrylate(MEO2MA) and ZQMA by utilizing a PEG-based macroRAFT agent. Following similar procedures, PEG-b-P(St-co-RhBEA) amphiphilic diblock copolymer and PEG-b-P(MEO2MA-co-Coum) DHBC were also synthesized, where P(St-co-RhBEA) was a RhBEA-labeled polystyrene(PS) block. At room temperature in aqueous solution, almost nonfluorescent PEG-b-P(MEO2MA-co-ZQMA) can effectively bind Zn2+ ions, leading to prominent green fluorescence enhancement due to the coordination of ZQMA with Zn2+ ions. However, by mixing red-emitting PEG-b-P(St-co-RhBEA) and blue-emitting PEG-b-P(MEO2MA-co-Coum) with PEG-b-P(MEO2MA-co-ZQMA) at an appropriate ratio, three color transitions could be observed. In the absence of Zn2+ ions, a mixed pink fluorescent originating from Coum and RhBEA was observed; upon the addition of a certain amount of Zn2+ ions, the green fluorescence enhanced dramatically, leading to a white fluorescence readout. By further increasing the amount of Zn2+ ions, the green fluorescence further enhanced and overwhelmed the blue and red emissions, leading to a green-dominant mixed-fluorescence emission. In addition, upon increasing the temperature, the fluorescence of Coum decreased considerably due to the fluorescence-resonance energy transfer(FRET) between Coum and ZQMA moieties. In this way, a ratiometric fluorescent thermometer can be constructed.
