Reversible photoswitching aggregation and dissolution of spiropyran-functionalized copolymer and light-responsive FRET process

Well-defined, reversibly light-responsive amphiphilic diblock copolymer grafted with spiropyran, was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. The copolymer self-assembles into polymeric micelles in water and exhibits reversible dissolution and re-aggregation characteristics upon ultraviolet (UV) and visible (Vis)-light irradiation. The fluorescence response of spiropyran immobilized onto the copolymer was light switchable. When nitrobenzoxadiazolyl derivative (NBD) dyes are encapsulated into the core of the micelles, a reversible, light-responsive, dual-color fluorescence resonance energy transfer (FRET) system is constructed and processed, which is well regulated by alternatively UV/vis irradiation. We anticipate these photoswitchable and FRET lighting up nanoparticles will be useful in drug delivery and cell imaging or tracking synchronously. (C) 2013 Si-Chong Chen and Yu-Zhong Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.