Preparation Of Spiropyran-containing Light-responsive Polymer Composite Materials

Spiropyran and its derivatives are a class of common photochromic organic compounds. Owing to its molecular structure, both of physical and chemical properties will change evidently after light irradiation, it has been introduced to a variety of light-responsive materials applied in the fields of biomedical, photoelectron devices.Polymeric micelles based on spiropyran have been developed as drugcarrier and applied in biomedical field for light-controlled drug delivery. However, such kind of polymeric micelles were still inadequate in drug loading performance, biomedical imaging, active tumor targeting, etc., To improve these shortages in practical application, we designed and fabricated two drug delivery systems based on the composite of spiropyran-containing polymer micelles and inorganic nanoparticles:(1) we designed and prepared a light-responsive drugcarrier based on spiropyran-containing light-responsive copolymer(PRMS-FA) coated on hollow mesoporous silica(HMS) nanoparticles via a facile self-assembly process. With good biocompatibility and drug capability, HMS that modified with hydrophobic octadecyltrimethoxysilane(C18) was considered as an ideal base material. The amphiphilic copolymer containing spiropyran moieties could shift hydrophilic-hydrophobic balance to be hydrophilic upon UV light(λ=365 nm) irradiation,resulting in the polymer layer breaking away from the hydrophobic surface of HMS core and the uncaging and release of the pre-loaded model drugs. Simultaneously, the fluorescence resonance energy transfer(FRET) process based on the structure transition of PRMS-FA could be observed, which was considered to act as a real-time monitor for the process of light-triggered drug release. The model experiments in vitro were used to test and verify the properties of composite nanocarrier and the results showed it has good biocompatibility, along with active tumor targeting performance to folate receptor over-expressed tumour cells, safe to normal cells and light-triggered drug release with real-time monitoring.(2) lanthanide upconversion nanoparticles(UCNPs) co-doped with Yb3+ and Tm3+were introduced into the nanocarrier with the photo-responsive polymeric shell containing spiropyran groups which is utilized as the photo trigger in our previous work. With the introduction of the caged UCNPs, the drug release of the nanocomposite could be controlled by NIR light directly as well as the bioimaging based on upconversion luminescence(UCL). lanthanide UCNPs co-doped with Yb3+and Tm3+were prepared and then caged with mesoporous silica layer(MUCNP) for drug loading. After modified with long hydrophobic alkyl chains(C18), MUCNPs were coated by the amphiphilic polymer PSMN-FA through hydrophobic van der Waals interaction via a self-assembly process to obtain the nanocarrier MUCNP@C18@PSMN-FA. With the near-infrared(NIR) light(λ=980 nm)irradiation, the caged UCNPs emitted luminescence at UV region, which could result in the structure transition of amphiphilic copolymer and separating from MUCNPs,immediately following the release of the pre-loaded drugs after targeted in cancer cells.The model experiments in vitro were used to verify the performance of the nanocarrier MUCNPs@C18@PSMN-FA. The results suggested that it could provide active tumor targeting to folate receptor over-expressed(FR+) tumor cells. Both in vitro and in vivo studies confirmed the feasibility of NIR-triggered drug release and suggested a potential application of this multifunctional nanocarrier in biomedical field.Based on the light-responsive properties which were studied above, we introduced spiropyran to sponge absorbent material for hydrophobic surface modification and controlled desorption:(3) we demonstrated a facile method to fabricate robust and superhydrophobic material through the commercial melamine-formaldehyde(MF) sponges and light-responsive spiropyran derivative(SPMA) through a surface radical copolymerization process. The MF sponges were first modified with vinyl for the copolymerization via a facile solution-immersion process. Afterwards, light-responsive spiropyran methacrylate monomers were copolymerized with vinyl-modified MF sponges to fabricate polymer-MF sponges composites(denoted SP-MF sponges). This surface copolymerization process resulted in the sponge-like material from being amphiphilic to superhydrophobic with a water contact angle(CA) of 155.5o. The superhydrophobic SP-MF sponge exhibited high selectivity and excellent adsorption performance for a range of normal oils and organic solvents from 70 to 154 times its own weight. Since the hydrophobic polymer of theSP-MF sponge could transform to be hydrophilic with UV irradiation, the SP-MF sponge would change to be hydrophilic which resulted in a light-controlled oil desorption process.These findings offer a new responsive adsorbent material and a new approach for oil recovery which have a potential application in the filed of environmental science.