The Design And Synthesis Of Mesoporous Silica Nanoparticles Based Photo-responsive Drug Delivery Systems

Mesoporous silica nanoparticles(MSNs) have proven to be ideal carriers for drug delivery systems(DDS),due to their unique mesoporous structure, large surface area, stable and rigid frameworks, ease of functionalization and biocompatible. Based on the above facts. In this thesis, using physically encapsulation of drug, a several novel photo-responsive DDS based on the modified MSNs were synthesized and their potential application in drug control-release were confirmed. Details are as follows:(1) The photo-responsive DDS based on MSNs with the7-aminocoumarin for light-control and β-cyclodextrin-dextran as snap-top was synthesized. The snap-top was achieved by the inclusion association between (3-cyclodextrins and adamantane,and blocked the pores. The encapsulation capacity of drug was successfully increased by changing the synthetic route.The controlled-release of camptothecin was confirmed by HPLC,70%of maximum release was obtained after120min under light irradiation, nearly50%higher than that in dark.(2) Series of photo-responsive amphiphilic diblock copolymers based on mPEG-PCL of different molecular weight with o-nitrophenyl were synthesized. To constitute a photo-responsive DDS, these copolymers were grafted on the surface of MSNs and blocked the pores by the self-assembled mPEG-PCL micelles due to their amphiphilic properties. Then we studied the encapsulation capacity of the micelles with different mPEG-PCL molecular weight, confirmed the control-release of doxorubicin and tested the capability of photo-induced charge reversal on surface for further cell experiments.Since the linear block polymer structure itself, the resulting system for the drug blocking was not very strict and the leakage was relatively high. So need to further improve and optimize the conditions.(3)By introduction of o-nitrobenzyl photosensitive groups and Michael addition reaction between maleimide and thiol,the photo-responsive microgels were formed on MSNs through layer by layer technique (LBL) to construct a new photo-responsive DDS.Then we studied the encapsulation capacity of the microgels of different LBL materials, and confirmed the control-release process of doxorubicin. This system is expected to achieve excellent biocompatibility and multiple drug loading or functionalization.