title: Modulation of the sensitive temperature range of fluorescent molecular thermometers based on thermoresponsive polymers.
abstract: Fluorescent molecular thermometers based on polymers showing a temperature-induced phase transition and labeled with polarity-sensitive fluorescent benzofurazans are the most sensitive known. Here we show a simple and effective method for modulating the sensitive temperature ranges of fluorescent molecular thermometers based on such temperature-responsive polymers. 4-N-(2-acryloyloxyethyl)-N-methylamino-7-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole was adopted as a polarity-sensitive fluorescent benzofurazan, and nine copolymers of two kinds of acrylamide derivative (N-n-propylacrylamide, N-isopropylacrylamide, and/or N-isopropylmethacrylamide) with a small amount of DBD-AE were obtained. The fluorescence intensities of these copolymers in aqueous solution sharply increased with increasing temperature over a small range (6-7 degrees C). In contrast, these fluorescent molecular thermometers differed from one another in the sensitive temperature range (between 20 and 49 degrees C). Moreover, the sensitive temperature ranges were well related to the acrylamide ratios in feed. In addition, the responses from these fluorescent molecular thermometers to the change in temperature were reversible and exactly repeatable during 10 cycles of heating and cooling (relative standard deviation of the fluorescence intensity, 0.44-1.0%).
authors.affiliation: Department of Chemistry, Faculty of Science, Nara Women's University, Kitauoya-Nishimachi, Nara 630-8506, Japan. S.Uchiyama@qub.ac.uk
authors.forename: Seiichi
authors.initials: S
authors.lastname: Uchiyama
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Matsumura
authors.forename: A Prasanna
authors.initials: AP
authors.lastname: de Silva
authors.forename: Kaoru
authors.initials: K
authors.lastname: Iwai
mesh_terms: D001583:Benzoxazoles / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D015394:Molecular Structure; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D013696:Temperature; D013821:Thermometers
chemical_list: D001583:Benzoxazoles; D005456:Fluorescent Dyes; D011108:Polymers; C020160:benzofurazan