| Core-shell structure nanoparticles are attracting considerable attention because of their applications in drug delivery,catalysis carrier,and nanomedicine.In this thesis,SiO2@SiO2 core-shell structure with tunable void and shell thickness was successfully prepared for the first time using SiO2-poly?buty acrylate??PBA?-poly?2-?dimethylamino?ethyl methacrylate??PDMAEMA??SiO2-PBA-b-PDMAEMA?as the template and tetraethoxysilane?TEOS?as the silica source.An amphiphilic copolymer PBA-b-PDMAEMA was first grafted onto the SiO2 nanosphere surface through activators regenerated by electron transfer for atom transfer radical polymerization.TEOS was hydrolyzed along with the PDMAEMA chain through hydrogen bonding,and the core-shell structure of SiO2@SiO2 was obtained through calcination to remove the copolymer.The gradient hydrophilicity of the PBA-b-PDMAEMA copolymer template facilitated the hydrolysis of TEOS molecules along the PDMAEMA to PBA segments,thereby tuning the voids between the SiO2 core and SiO2 shell,as well as the SiO2 shell thickness.A series of characterizations?1H NMR,TG,FT-IR,TEM/SEM?indicated that the amphiphilic block copolymer PBA-b-PDMAEMA were grafted onto SiO2 nanoparticle surfaces.The thickness of PBA polymer layer was about 13 nm.TEM and the nitrogen adsorption-desorption indicated the obtained SiO2@SiO2 core-shell structure had hierarchically nanoporous structures.The voids were about 10-15 nm and the shell thicknesses were about 4-11 nm when added different amounts of DMAEMA monomer.In addition,the space was about 11 nm when the DMAEMA molar was 10.08,the space was about 12 nm when the DMAEMA molar was 15.42,and the space was about 14 nm when the DMAEMA molar was 20.48.SiO2@SiO2 core-shell structures with tunable void and shell thickness were employed as supports for the loading and release of doxorubicin hydrochloride?DOX?.The DOX loading content of SiO2@SiO2-1,SiO2@SiO2-2 and SiO2@SiO2-3 are approximately 19.37%,19.51% and 21.03%,respectively.The entrapment efficiencies of SiO2@SiO2-1,SiO2@SiO2-2 and SiO2@SiO2-3 are approximately 71.04%,71.52% and 77.21%.The DOX released from SiO2@SiO2-1-D?SiO2@SiO2-2-D and SiO2@SiO2-3-D are approximately 42.0?42.7 and 44.0 wt.% at p H 7.4 in 60 h.Through the comparison,we find that the samples demonstrated good loading capacity and controlled release rate of DOX.The method and mechanism for preparing SiO2-PBA-PDMAEMA and SiO2@SiO2 can be extended to other tunable inter-lamellar voids of core-shell structure and provided an improved method,thereby expanding its application scope. |
PDF Full Text Request