A photo, temperature, and pH responsive spiropyran-functionalized polymer: Synthesis, self-assembly and controlled release

Here we report a photo, temperature and pH responsive copolymer which was conveniently synthesized by quaternization between the spiropyran derivative (SPNeCl) and dimethylaminoethyl units of poly(dimethylaminoethyl methacrylate) (PDMAEMA). In aqueous solution, the synthesized copolymer P(DMAEMA-SP) could self-assemble into polymeric nanoparticles. The spiropyran-quaternized segments endow the system with UV and visible light responsiveness and un-quaternized segments of PDMAEMA endow the system with temperature and pH responsiveness. Multiple stimuli-triggered morphological changes of the polymeric nanoparticles were revealed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The controlled release of hydrophobic dyes from the polymeric nanoparticles under the stimulation of UV light, temperature and pH could be realized. When the stimuli such as pH and UV light were synergistically applied, the release efficiency of encapsulated molecules would be enhanced greatly. The multiple stimuli-responsive self-assembled polymeric nanoparticles show promising potential as new nanocarriers for precisely controlled release of encapsulated molecules. (C) 2015 Elsevier Ltd. All rights reserved.