NIR light and enzyme dual stimuli-responsive amphiphilic diblock copolymer assemblies

Using atom transfer radical polymerization (ATRP) and macromolecular azo coupling reaction, both o-nitrobenzyl (ONB) group and azobenzene group were efficiently incorporated into the center of the amphiphilic diblock copolymer chain. The prepared diblock copolymer was well characterized by UV-vis, H-1 NMR, and GPC methods. Self-assembly of the amphiphilic copolymer in selected solvents can result in uniform self-assembly aggregates. In the presence of external stimuli [upconversion nanoparticles (UCNPs)/NIR light or enzyme], the amphiphilic diblock copolymer chain could be broken by the cleavage of ONB or azobenzene group, which would lead to the disruption of the self-assembly aggregates. This photo- and enzyme-triggered disruption process was proved by using transmission electron microscopy (TEM) and GPC method. Fluorescence emission spectra measurements indicated that the release of Nile red, a hydrophobic dye, encapsulated by the self-assembly aggregates, could be successfully realized under the NIR light and enzyme stimuli. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2450-2457