| Spiropyran derivatives are typical light-responsive molecules.The spiropyran-based photoresponsive materials have photoisomerization properties and the spiropyran groups would exhibit different hydrophilic-hydrophobic structures under different light irradiation.Spiropyran molecules have two states:closed-loop state(SP,spiropyran structure)and open-loop state(MC,merocyanine structure).The spiropyran molecules are in hydrophobic SP structures under dark or visible light(Vis)irradiation and in hydrophilic MC structure under ultraviolet(UV)irradiation.In addition to light stimulation,pH stimulation can also induce protonation or deprotonation process of spiropyran molecules,resulting in structural changes.Utilizing the change of molecular structure and the photochemical properties of spiropyran before and after irradiation,it can be widely used in the fields of optical recording materials,optical devices,chemical sensing,drug controlled release.In this paper,spiropyran-based photoresponsive polymer nanoparticles synthetization and released properties are investigated under different external stimulus.The research is divided into four parts:The first part is the preparation and properties of UV light,pH and temperature triple-responsive spiropyran-based polymer micellar nanoparticles.The amphiphilic polymers were prepared by using photoresponsive spiropyran group and temperature responsive group N-isopropylacrylamide under the random copolymerization.The amphiphilic polymers can form micelles nanoparticles with hydrophobic core and hydrophilic shell by self-assembly process in aqueous solution.Through the self-assembly process of amphiphilic polymer in aqueous solution,the hydrophobic dye coumarin 102 has been loaded into the micellar nanoparticles.The effects of temperature,pH and synergistic effect on the morphology and properties of the nanoparticles are studied.The regularity between the different stimuli and the molecular release rate was revealed,the efficient release of the model molecular coumarin 102 was achieved and in the gentle field coordination to achieve the nanoparticles effective controlled release the object molecules.The results show that the nanoparticles can be used as an intelligent release system with excellent performance.The second part is the preparation and properties of near infrared light and pH dual-responsive spiropyran-based UCNPs@polymer composite nanoparticles.The amphiphilic spiropyran-based polymers can form micelles nanoparticles,in which spiropyran-based hydrophobic parts form the core and poly(N-isopropylacrylamide)hydrophilic parts form the shell by self-assembly process in aqueous solution.With the self-assembly process of the polymer,hydrophobic upconversion nanoparticles(UCNPs)and guest molecules can be loaded into core of the micelles nanoparticles and formed UCNPs@Polymer composite nanoparticles.Under near infrared light irradiation,UCNPs can emit UV light and visible light.The emitted UV light can cause the hydrophobic SP isomerized to hydrophilic MC.The effects of temperature,pH and synergistic effect on the morphology and properties of the composite nanoparticles were studied.The regularity between the different stimuli and the molecular release rate was revealed,and the efficient release of the model molecular coumarin 102 was achieved and in the gentle field coordination to achieve the nanoparticles on the object of the effective control of the release of molecules.The results of in vitro activity experiments show that nanocomposites could effectively controlled release the loaded drugs and successfully kill cancer cells under combined stimulation,which indicated that the nanocomposites could be used as an excellent drug release system with excellent performance.The third part is the preparation and properties of triple-responsive spiropyran-based polymer nano gel.The new light,pH and redox triple-responsive nanogel was obtained through emulsion polymerization with light responsive group spiropyran,pH responsive group acrylic acid and redox responsive crosslinker.The effects of different stimuli on the morphology and properties of nanogel were systematically studied:under UV irradiation,the nanogels could be swelled;under pH stimulation,the nanogels could be quickly swelled due to the protonation process of the AA groups;under DTT stimulation,the nanogels would be disassociated due to the disrupted crosslinking state on the nanogels.The effect of combined stimulation on the morphology and properties of nanogel was further studied,and the theory of the molecular release rate rules was revealed.The effective release of guest molecules achieved under mild conditions.The results of in vitro activity experiments showed that nanocomposites could effectively controlled release the loaded drugs and successfully kill cancer cells under combined stimulation,which indicated that the nanogels could be used as an excellent drug release system with excellent performance.The fourth part is the preparation and properties of near infrared(NIR)light,pH and redox triple-responsive UCNPs@spiropyran-based polymer composite nanogels.The new NIR light,pH and redox triple-responsive UCNPs@polymer composite nanogels are prepared through emulsion polymerization with light responsive group spiropyran,pH responsive group acrylic acid,redox responsive crosslinker and composite with UCNPs.The loaded UCNPs could absorb near infrared light and convert it into ultraviolet(UV)light,so that the SP group on the composite nanogels can be isomerized to MC group under the stimulation of the near infrared light.The effects of near infrared light,pH,redox substances and synergistic stimuli on the morphology and properties of the nanogels were studied.The regularity between the different stimuli and the molecular release rate was revealed,and in the synergistic stimulation,to achieve a mild condition of nanogels on the effective control of drug release.The results show that the nanoparticles can be used as an intelligent release system with excellent performance. |
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