| Due to their excellent biocompatibility, modifiable Si-OH on surface, goodmonodispersity, innate ability of sustained drug release, adjustability of particle and poresize, large specific surface area and high drug loading capacity, hollow mesoporous silicananoparticles (HMS) have received much attention in biomaterials. However, in thepractical application of drug delivery, there are still some defects in satisfying therequirements of “zero” release before carrier reaching target goals and controlled release.To solve the problem above, three part works were discussed below：(1) We modified the Hollow mesoporous silica nanoparticles with the pH-sensitiveamphiphilic diblock copolymer to achieve the controlled drug release of carrier in cancercells. Firstly, hollow mesoporous silica nanoparticles were synthesized by model method,and an acid-sensitive amphiphilic polymer poly(PDM-b-PEGMEM) was grafted on thesurface of the nanoparticles by atom transfer radical polymerization (ATRP), the preparednanocomposites can achieve controlled drug releaas in acid enviroment of cancer cells. Weuse Nile Red and DOX with red fluorescence as model drugs and use fluorescencespectrophotometry to test the abilities of drug loading and release. The results showed thatthe nanocomposites possess high drug loading efficient about80%and good capacity ofcontrolled-release. Normal human liver cells L02and human lung cancer cells7402wereused as target cells, the results showed that the nanocomposites only release drug in cancercells.(2) We modified the hollow mesoporous silica nanoparticles with fluorescencerare-earth and self-assemble with pH-sensitive amphiphilic diblock copolymer, thismaterials not only can achieve controlled drug release, but also can used foe cells imaging.Firstly, Fluorescence hollow mesoporous silica nanoparticles were synthesized bymodifying rare-earth via sol-gel process, then the fluorescence nanoparticles weremodified by long alkyl chains and coated with acid-sensitive amphiphilic polymer PMD through hydrophobic van der waals interactions. The results of characterization such asTEM and DLS reveal that the material shows excellent monodisperse sphericalmorphology and narrow size distribution (180nm) withhollow-core@mesoporous-silica-shell@thin-polymer-film structure. We use IBU as themodel drug and the drug loading content of the system is as high as834mg/g(drug/carrier). The time of releasing about80%drug was prolonged from50h to150h bythe effect of modified C18. The loaded drug is selectively released in mildly acidicenvironment by coating pH-sensitive polymer film. Besides, the nanocomposites wassuitable for cell imaging by modify the rare-earth.(3) Hollow mesoporous silica nanoparticles were modified by β-cyclodextrin andself-assemble with amphiphilic polymers contained azobenzene groups, and this carrierscan release drugs in a control manner under UV-irradiation. β-Cyclodextrin (β-CD) wasmodified on the surface of hollow mesoporous silica nanoparticles by “click” reaction, andan amphiphilic polymer poly(PPHM-co-PEGMEM)(PPP) contain azobenzene groups wassynthesized. The azobenzene groups with lower energy state trans-structure can enter thecavity of β-CD under easily. After UV-irradiation, the structure of PPP would change intohigh energy state cis-structure and emerge from the β-CD cavity. This progress wasreversible and can be used in light-triggered drug release. The results of characterizationsuch as TEM and DLS reveal that the material shows excellent monodisperse sphericalmorphology and narrow size distribution. UV spectrophotometry comfirmed the carrieronly release drug under UV-irradiation. The nanocomposites have the performance withartificial control of drug release. |
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