title: Thermo- and light-regulated formation and disintegration of double hydrophilic block copolymer assemblies with tunable fluorescence emissions.
abstract: We report on thermo- and light-regulated formation and disintegration of double hydrophilic block copolymer (DHBC) micelles associated with tunable fluorescence emissions by employing two types of DHBCs covalently labeled with fluorescence resonance energy transfer (FRET) donor and acceptor moieties, respectively, within the light and temperature dually responsive block. Both DHBCs are molecularly soluble at room temperature in their aqueous mixture, whereas, upon heating to above the critical micellization temperature (CMT, ~31 °C), they coassemble into mixed micelles possessing hydrophilic coronas and mixed cores containing FRET donors and acceptors. Accordingly, the closer spatial proximity between the FRET pair (NBDAE and RhBEA moieties) within micellar cores leads to substantially enhanced FRET efficiency, compared to that in the non-aggregated unimer state. Moreover, upon UV irradiation, the light-reactive moieties undergo light-cleavage reaction and transform into negatively charged carboxylate residues, leading to elevated CMT (∼46 °C). Thus, thermo-induced mixed micelles in the intermediate temperature range (31 °C < T < 46 °C) undergo light-triggered disintegration into unimers, accompanied with the decrease of FRET efficiency. Overall, the coassembly and disassembly occurring in the mixed DHBC solution can be dually regulated by temperature and UV irradiation, and most importantly, these processes can be facilely monitored via changes in FRET efficiency and distinct emission colors.
authors: CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors: Yonghao
authors: Y
authors: Wu
authors: Huamin
authors: H
authors: Hu
authors: Jinming
authors: J
authors: Hu
authors: Tao
authors: T
authors: Liu
authors: Guoying
authors: G
authors: Zhang
authors: Shiyong
authors: S
authors: Liu
mesh_terms: D003116:Color; D004396:Coloring Agents / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D057927:Hydrophobic and Hydrophilic Interactions; D008027:Light; D008823:Micelles; D011108:Polymers / Q000737:chemistry*; D013696:Temperature
chemical_list: D004396:Coloring Agents; D008823:Micelles; D011108:Polymers