Controllable Synthesis and Application of Flexible Hollow Periodic Mesoporous Organosilica Nanocapsule
Author:Zuo Shi Yong
Supervisor:jie ren guo
Hollow periodic mesoporous organosilica(HPMO)has been widely used in chemistry,energy,biomedicine,and other fields.However,there are still some limitations in the controllable synthesis and surface properties regulation of HPMO.(1)It is difficult to regulate the inner surface properties of HPMO cavity and realize the high drug loading capacity;(2)It is difficult to regulate the thickness and mechanical properties of HPMO shell and control the drug loading and releasing process.(3)It is challenging to realize the large-scale synthesis of HPMO due to their complicated and tedious functionalization process.In this thesis,the synthesis,properties,and application of flexible hollow periodic mesoporous organosilica(HPMOs)were studied.Firstly,ultra-thin flexible HPMO nanocapsules were synthesized in large-scale by one-step oil/water microemulsion approach.Secondly,the synthesis mechanism of nanocapsules was studied.It was found that the shell thickness,surface properties and mechanical properties of nanocapsules could be precisely regulated by changing reaction variables,such as silane dosage,p H value,and alkane chain length.Finally,the resulted nanocapsules successfully achieved super-high loading of hydrophobic drugs and high-efficiency conjugation of oil-soluble nanoparticles because of their hydrophobic inner surface.The contents mainly make up of three parts:1.Flexible HPMO nanocapsule with ultra-thin shell was synthesized by a one-step method in O/W microemulsion system,using alkane microemulsion as the oil phase template,BTSE as the precursor,and Na OH as the catalyst.The as-prepared nanocapsules have ultra-thin shell thickness(4 nm),large internal cavity(about 300 nm),large mesoporous(4.2 nm)and high surface area(1139 m2g-1).The shell thickness of the hollow capsule can be adjusted between 4-38 nm,and Young’s modulus can be adjusted between 36.9-65.1 Mpa through changing the amount of organosilica precursor.Zeta potential,infrared spectroscopy,and oleic acid adsorbing-swelling experiments confirmed that the hollow nanocapsule had a hydrophilic outer surface and a lipophilic inner surface,which provided new opportunities for drug loading and further functionalization.2.HPMO nanocapsules successfully realized high loading capacity of hydrophobic drugs due to their lipophilic property of the inner surface.Firstly,the adsorption capacity of nanocapsules with different shell thickness for various solvents was studied.It was found that nanocapsules had high adsorption capacity for dichloromethane,oleic acid,toluene,hexane,and other organic solvents.Secondly,it is found that the loading capacity is related to the thickness of the shell.The thinner the shell,the stronger the adsorption capacity.Furthermore,the loading capacity of hydrophobic drugs including paclitaxel,bupivacaine free base and ibuprofen could reach up to 104%,98.6%,and 44.3%,respectively(Loading capacity=mass of drug-loaded/mass of nanocarriers).Finally,the drug-releasing and cytotoxicity studies showed that the hollow nanocapsules had low cytotoxicity,and the paclitaxel-loaded nanocapsules improved drug-releasing properties and chemotherapeutic efficacy compared with free paclitaxel.3.The further functionalization of flexible HPMO nanocapsules was studied.Firstly,oleophilic Fe3O4 and Cu S were directly added into the reaction system of HPMO,as a result of magnetic Fe3O4@HPMO nanocomposite and photothermal Cu S@HPMO nanocomposite by one-step reaction.Additionally,Ag@HPMO composites were prepared by introducing oleylamine coordination Ag+ into the oleophilic cavity of HPMO nanocapsules.It is found that they have excellent heterogeneous catalytic properties.These results demonstrated that this reaction system provides a new way for the preparation of flexible hollow periodic mesoporous organosilica nanocapsules and their multi-functionalization.