A Controlled Release Of Drug Molecules By Assembly And Self-Assembly Drug In Mesoporous Silica

In 1992, the Mobil Scientists reported the synthesis of mesoporous materials bythe use of self-assembled surfactant molecular aggregates as the structure-directingagents. This kind of materials have attracted much attention due to its novel features,such as high regular and unique tunable nanometer pore sizes, high surface area,large pore volume, and tailorable surface chemical properties. The main contents ofmesoporous molecular sieves range from synthesis, morphology, modification, andassembly, and it have made great progress in the field of catalysis, adsorption,separation, purification, optics, preparation of nano-materials et al. during the pastyears. Self-assembly chemistry plays a key role all along the process of study anddevelopment of mesoporous molecular sieves. Scientists proposed variable synthesismechanisms and routines to describe the formation of mesoporous molecular sievesby investigating van der wals, h-bond, hydrophilic and hydrophobic interaction andweak static interaction. While the proposition of new synthesis mechanisms androutines undoubtedly create a lot of chances to prepare novel materials. The novelroutine of S-N+～I-proposed by che et al. has brought new chance to synthesize newmesoporous materials. Meanwhile, the study of mesoporous silica materials haspromoted the development of host-guest chemistry. Mesoporous material can havevariable properties and capabilities by means of modification and assembly. Recently,hierarchically porous material with complicated morphology and ordered porositieshave been prepared by using nature bi-materials with lower cost and environmentfriendly,which further broaden the study of mesoporous materials.In this paper, based on the unique self-assembly process of mesoporous molecularsieves and host-guest chemistry. In order to prepare sustained/controlled releasesystem, drugs have been incorporated inside of mesoporous silica by self-assemblyand assembly process. Meanwhile, hierarchically porous materials have beensynthesized by using nature plants.Controlled release technologies are becoming more and more important in modernmedication and pharmaceuticals. Amorphous colloidal and porous silica are used asdrug carrier and tissue stuffing in pharmaceutical technology. A new application ofmesoporous silica as drug delivery system has been explored since 2003, and nowthere has been growing interest in the use of mesoporous silica assustained/controlled drug delivery system.In order to control release water-soluble drug, Captopril has been incorporated inthe channel of MCM-41, and the drug loading and release profiles had been studied.It was found that the largest drug loading occurred in 0.1 M drug solution in 2 h.Meanwhile, this drug can be sustained release from MCM-41, which confirmedmesoporous silica can be served as water-soluble drug carrier. The influence ofmorphology of mesoporous silica on drug loading and release profiles wasextensively studied for the first time. It was found that the loading and releasekinetics (in vitro in simulated stomach fluid) showed that both of them were affectedby not only the pore diameter but also the morphologies (pathway) of mesoporoussilica materials. A rapid drug loading could be achieved by either enlarging pore sizeor reducing particle size. And CapH2/SBA-15 delivery system with the largest porediameter of 7.39 nm exhibited the fastest release rate. While CapH2/MCM-4112system with the smallest pore diameter of 1.65 nm and sphere morphology (120～250 nm in size) had a faster release rate than that of CapH2/MCM-4116 system with2.17 nm pore diameter and rodlike morphology (ca. 20 μm in length). So awell-controlled and economical system for delivery of CapH2 can be achieved byadjusting appropriate pore size and suitable morphology of mesoporous silicamaterials. The amount of the drug loading is directly related to the BET surface area.Higher surface area usually has larger drug loading amount. Meanwhile, an attemptwas made to control release Captopril by tailoring the surface properties ofmesoporous silica via stepwise silylation. This study shows that drug release profilescan be controlled by tailoring the surface properties and pore size. And awell-defined drug controlled release could be achieved by tailoring the surfaceproperties of mesoporous silica materials via regulating the degree of silylation.Therefore, it could be concluded that the surface characteristics of mesoporouscarrier system play an important role in drug delivery profiles.In addition, we have achieved a novel and effective method using drug as templateto synthesize Ibu/mesoporous silica system by a one-step process. The reportedIbu/MS system possesses ordered hexagonal mesopore structure, and gives awell-sustained release profiles. And the release mechanism follows an anomalousnon-Fickˊs transport. Additionally, a series of mesoporous silica materials withsimilar pore sizes, variable morphologies, and pore geometries have been employedto control Ibuprofen drug delivery under in vitro conditions. It has been revealed thatthe amount of drug-loading is directly related to the BET surface area, pore geometry,and pore volume of mesoporous silica. Large BET surface area of hexagonalsymmetry mesoporous silica carriers usually have large drug-loading amount. Thedelivery profiles show that the drug release profiles are related to the particle sizes(pathways) induced by their morphologies in the case of the pore diameter in therange of 1.96-2.45 nm. It was also found that the pore geometry affects drugdelivery profiles as well. Therefore, this study indicates that the morphology must betaken into account while the drug delivery profiles of mesoporous silica carriers areinvestigated. And the drug release profiles could be regulated by tailoring themorphology of the mesoporous silica. 3D interconnected pore system of MCM-48-Efacilitates fast drug release due to well-massed transportation.The mesoporous silica and drug-loaded samples were characterized by X-raydiffraction, Fourier transform IR, N2 adsorption and desorption, Scanning electronmicroscopy (SEM) and transmission electron microscopy (TEM), 29Si/MAS NMR,and 13C/MAS NMR, elemental analysis, UV-VIS, respectively. This study confirmedmesoporous silica can be served as a well-defined drug controlled release system.Finally, a series of plants with ordered macroporous have been explored tosynthesize hierarchically porous materials using dual-templet method. Thesynthesized hierarchically porous materials can sustained release drug molecules, andmay be used as new tissue repaired materials.