Significant Fluorescence Enhancement of Spiropyran in Colloidal Dispersion and Its Light-Induced Size Tunability for Release Control

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• 作者：Yinan Xue ; Jintao Tian ; Weiguo Tian ; Peizhen Gong ; Jinhui Dai ; Xin Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：September 3, 2015
• 年：2015
• 卷：119
• 期：35
• 页码：20762-20772
• 全文大小：1042K
• ISSN：1932-7455

文摘

The spiropyran-contained nanomicelles with excellent fluorescence emission in colloidal dispersion are fabricated by grafting spiropyran onto a PAA鈥揚S diblock copolymer followed by self-assembling under ultraviolet irradiation in nonpolar solvent of toluene. The spiropyran species is embedded in interior high polar cores of the micelles that can promote the concentration of the merocyanine form of spiropyran. Meanwhile, the embedding of spiropyran inside the micelles produces effects of conformational constraint and uncontact to solvent. The synergy of the above three effects significantly enhances the fluorescence emission of the micelles in colloidal dispersion whereas in the case of the pure spiropyran it shows virtually no emission in toluene. With the aid of ultraviolet and daylight, the fluorescent micelles dramatically shows light-induced size tunability and excellent recyclability, corresponding to the significant change in polarity of the copolymer chain that is caused by the reversible transformation between weak polar spiropyran and zwitterionic merocyanine. Loading and controlled release of rhodamine 6G as a typical polar drug substance is successfully achieved with the micelles. These experimental results may bring about more promising applications of spiropyran species beyond their photochromic properties in microscopic fields such as nanocarrier for drug delivery or micro detector for biosensor.