Fluorescent Molecular Thermometers Based on Polymers Showing Temperature-Induced Phase Transitions and Labeled with Polarity-Responsive Benzofurazans
详细信息 查看全文
- 作者：Seiichi Uchiyama ; Yuriko Matsumura ; A. Prasanna de Silva ; and Kaoru Iwai
- 刊名：Analytical Chemistry
- 出版年：2003
- 出版时间：November 1, 2003
- 年：2003
- 卷：75
- 期：21
- 页码：5926 - 5935
- 全文大小：180K
- 年卷期：v.75,no.21(November 1, 2003)
- ISSN：1520-6882
文摘
Poly(N-isopropylacrylamide) in aqueous solution undergoes a phase transition at ~32 
deg.gif">C. The fluorescenceproperties of benzofurazans are affected by solvent polarity. We combine these two characteristics for the first timeto develop sensitive fluorescent molecular thermometers.Five fluorescent monomers having a benzofurazan skeleton were synthesized, and the copolymers of N-isopropylacrylamide (NIPAM) and a small quantity of thefluorescent monomer were obtained to investigate theirfluorescence properties. With increase in temperature, thecopolymers in water showed the temperature-inducedphase transition at ~32 deg.gif">C and the fluorescence intensities of the copolymers concurrently increased. Especially,for the copolymer of 4-N-(2-acryloyloxyethyl)-N-methylamino-7-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole and NIPAM, the fluorescence intensity at 37 deg.gif">C was13.3-fold that seen at 29 deg.gif">C. The sensitive range oftemperature of these fluorescent molecular thermometersis changed by the replacement of the NIPAM units byN-isopropylmethacrylamide or N-n-propylacrylamide unitsin the copolymers. The basis of these fluorescent molecular thermometers is the decrease in the microenvironmental polarities near the main chains of the copolymerswith increasing temperature, as confirmed from themaximum emission wavelengths of the benzofurazan unitsin the copolymers. The responses from the copolymersto the change in temperature are reversible and exactlyrepeatable during at least 10 cycles of heating and cooling.
deg.gif">C. The fluorescenceproperties of benzofurazans are affected by solvent polarity. We combine these two characteristics for the first timeto develop sensitive fluorescent molecular thermometers.Five fluorescent monomers having a benzofurazan skeleton were synthesized, and the copolymers of N-isopropylacrylamide (NIPAM) and a small quantity of thefluorescent monomer were obtained to investigate theirfluorescence properties. With increase in temperature, thecopolymers in water showed the temperature-inducedphase transition at ~32 deg.gif">C and the fluorescence intensities of the copolymers concurrently increased. Especially,for the copolymer of 4-N-(2-acryloyloxyethyl)-N-methylamino-7-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole and NIPAM, the fluorescence intensity at 37 deg.gif">C was13.3-fold that seen at 29 deg.gif">C. The sensitive range oftemperature of these fluorescent molecular thermometersis changed by the replacement of the NIPAM units byN-isopropylmethacrylamide or N-n-propylacrylamide unitsin the copolymers. The basis of these fluorescent molecular thermometers is the decrease in the microenvironmental polarities near the main chains of the copolymerswith increasing temperature, as confirmed from themaximum emission wavelengths of the benzofurazan unitsin the copolymers. The responses from the copolymersto the change in temperature are reversible and exactlyrepeatable during at least 10 cycles of heating and cooling.