2011年4月1日，我室纸维物理与化学研究部刘世勇教授研究组在ANALYTICAL CHEMISTRY上发表题为Responsive Polymers-Based Dual Fluorescent Chemosensors for Zn2+ Ions and Temperatures Working in Purely Aqueous Media的论文。

Source: ANALYTICAL CHEMISTRY Volume: 83 Issue: 7 Pages: 2775-2785 Published: APR 1 2011
Liu T (Liu, Tao)1, Liu SY (Liu, Shiyong)1
Addresses:
1. Univ Sci & Technol China, CAS Key Lab Soft Matter Chem, Dept Polymer Sci & Engn, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Anhui Peoples R China
E-mail Addresses: sliu@ustc.edu.cn

Reprint Address: Liu, SY (reprint author), Univ Sci & Technol China, CAS Key Lab Soft Matter Chem, Dept Polymer Sci & Engn, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Anhui Peoples R China

Abstract: We report on the fabrication of responsive double hydrophilic block copolymers (DHBCs)-based dual fluorescent chemosensors for Zn2+ ions and temperatures and investigate the effects of thermo-induced micellization and detection conditions on the probing sensitivity and binding reversibility of Zn2+ ions. A novel quinoline-based polarity-sensitive and Zn2+-recognizing fluorescent monomer (ZQMA, 6) was synthesized at first. Well-defined DHBCs bearing quinoline-based Zn2+-recognizing moieties (ZQMA) in the thermo-responsive block, PEG-b-P(MEO(2)MA-co-OEGM.A-co-ZQMA), were synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization of 2-(2-methoxyethoxy)ethyl methacrylate (MEO(2)MA), oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), and ZQMA in the presence of PEG-based macroRAFT agent. The OEGMA contents in the thermoresponsive block varied in the range of 0-12.0 mol % to tune their lower critical solution temperatures (LCSTs). At 20 degrees C, almost nonfluorescent PEG-b-P-(MEO(2)MA-co-ZQMA) molecularly dissolved in water and can selectively bind with Zn2+ ions over other common metal ions, leading to prominent fluorescence enhancement due to the coordination of ZQMA with Zn2+. At a polymer concentration of 0.2 g/L, the Zn2+ detection limit can be down to similar to 3.0 nM. PEG-b-P(MEO(2)MA-co-ZQMA) self-assembles into micelles possessing P(MEO(2)MA-co-ZQMA) cores and well-solvated PEG coronas upon heating to above the LCST, and the fluorescence intensity exhibit similar to 6.0-fold increase due to the fact that ZQMA moieties are now located in a more hydrophobic microenvironment. Compared to the unimer state at 20 degrees C, although PEG-b-P(MEO(2)MA-co-ZQMA) micelles possess a slightly decreased detection limit for Zn2+ (similar to 14 nM), reversible binding between ZQMA moieties and Zn2+ ions at 37 degrees C can be achieved, as evidenced by the on/off switching of fluorescence emission via the sequential addition of Zn2+ and EDTA. In vitro fluorescence imaging studies suggested that the micelles can effectively enter into living cells and sensitively respond to Zn2+ ions. This work represents the first example of a purely aqueous-based polymeric Zn2+ sensing system by integrating the well-developed small molecule Zn2+-sensing moieties with stimuli-responsive DHBCs.