| Mesoporous materials are outstanding due to their nign thermal stability, mechanical strength and non-toxic characteristics, so they are widely used in separation, catalysis and medical fields. Drug sustained-release with the sufficient amount and long time is a challenge to drive the development of mesoporous material. In order to achieve a long-term sustained release of drug molecule, it is crucial to build a suitable micro-environment in vessel where drug molecule can be stably trapped to retain the original conformation and biological activity. In this paper, SBA-15 and MCM-41 mesoporous silica were selected to optimize pore structures and modified with functional group for sustained release of heparin.1. First SBA-15 samples of different morphologies were examined to see their performances on heparin release, including the common one,3D net-linked one, superfine one and one with interconnected channels. In situ carbonization of template in SBA-15 sample resulted in silica-carbon composites. Apart from the advantage of omitting energy and time required for removal of template, the surface curvature of channel has been changed to optimize the adsorption performance. The content of remaining template was controlled by varying the carbonized temperature in 427-573 K, the resulted composites were tested to find their performance of immobilization. In addition, APTES was modified by one-pot synthesis into the channels of SBA-15 sample, thus offers channels positive charge to attract heparin through electro-static interaction. The optimal amine-loaded amount was also examined. All the samples were assessed with XRD, N2 adsorption-desorption, SEM, TEM and EA techniques, and their performance was evaluated in adsorption and release of heparin. Finally, the mechanism of heparin release on mesoporous material was tentatively studied by fitting the release profiles to some equations.2. Considering that heparin is a biomacromolecule with special long chain structure, unitary pore structure will not be favourable for its adsorption:The channel in zeolite is too narrow and will confine the diffusion procedure, while the mesoporous channel is too wide for a stable immobilization. This paper tried to synthesize mesoporous zeolite with hierarchical channel that combine both advantages. To transform amorphous silica in SBA-15 sample into zeolite crystal by dry-gel conversion method, and improve the adsorption performance by the electrostatic attraction between heparin and the cation site in zeolite. The crystallisation degree was controlled by adjusting the time of hydrothermal treatment, in order to possess zeolite channel and also remains relatively ordered meso-structure. In addition, Al-containing sample could provide more active cation site, so MCM-41 and SBA-15 samples modified with aluminum were also treated with crystallization procedure. All the mesoporous zeolite samples were investigated by use of XRD, BET and SEM, the immobilization and release of heparin were utilized to assess the actual function of these composites.3. This paper had a preliminary research of the mesoporous alumina and the graphene oxide on the adsorption performance. Mesoporous alumina was synthesized using the nonionic surfactant as the template, and was examined by TEM, BET. Graphene oxide has a high stability and is suitable for modification with other functional group, thus it is been widely used for the adsorption field. Subsequently, Graphene oxide can adsorb 6.4 times more than active carbon, and release more heparin than any mesoporous materials that ever been reported, exhibiting outstanding performance in release properties and can be further explored in future. |
PDF Full Text Request