Synthesis And Properties Of Inorganic Mesostructured Biomaterials

Inorganic biomaterials have been the subject of considerable attention due to their good stability in body, high mechanical strength, biocompatibity and hydrophilicity, acid or alkali resist, and innoxiousness. Winter has investigated the relationship between bioactivity in vitro and component, porous structure of inorganic biomaterials, the result implies that component and porous structure are important. The bioactivity in vitro would improve obviously when increasing the surface area and pore volume. Moreover, with porocity, a sharp fall of the rigidity of materials would happen, this is beneficial to the interface stress conduction and necessity achieving the stabile interface of materials. Ordered mesoporous materials are of great interest because of their periodic ordered regular channels, extremely high surface areas and pore volume, high thermal and hydrothermal stability, controllable morphology, and easily functionalized surface. After the addition of luminescent, magnetic substances or organic functional molecule, the mesoporous materials can be applied in target-drug delivery or selective adsorption/ separation of protein etc.. Recently, according to the designed strategy and synthetic method of mesoporous materials, large numbers of novel inorganic biomaterials were synthesized, such as mesoporous hydroxyapatite, mesoporous calcium carbonate, and mesoporous bioactive glass. These porous biomaterials offer an ideal platform for the main potential application in biology field such as remedy, therapy and bone repair.In this thesis, we prepared several mesostructured biomaterials as following:(1) synthesis and characterization of multi-lamellar mesostructured hydroxyapatites; (2) exploiting a simple, rapid and green route to fabricate hollow mesoporous silica; (3) synthesis of hollow calcium carbonate; (4) synthesis and characterization of a luminescent europium-doped inorganic porous bioglass sphere; (5) synthesis of magnetic particle-calcium phosphates. The obtained hollow mesoporous silica and europium-doped inorganic porous bioglass sphere were used as drug carriers to investigate the drug storage/release properties using ibuprofen (IBU) as a model drug.Learning from the study of Liang etc., there is meaningful relation between lamellar structure and mechanical property. Lamellar materials have an advantage of application in biology. Many researchers have paid attention to synthesize lamellar hydroxyapatite with innoxious surfactants as directing agents. To date, fatty acids have rarely been applied to produce mesostructured hydroxyapatite. Five familiar natural fatty acids were employed to prepare five lamellar mesostructured hydroxyapatites in alcohol/water mixed solvent. The results indicates that the interlayer spacing of HAs can be controlled and HAs with suitable interlayer spacing can be provided to accommodate functional molecules for further applications.Calcium carbonate is friendly to environment and organism because of the biocompatibility and biodegradability. There have been several reports on synthesizing hollow porous silica with calcium carbonate as hard template. However, most of the preparations require many tedious and time consuming synthetic steps, usually the hard template should be prapared firstly, following the centrifugation. washing and dispersion repeatly. A facile and rapid approach was exploited to synthesize hollow mesoporous silica materials. Ca(OAc)2 and NaHCO3 solution were mixed rapidly, then TEOS was dropped into the reaction mixture immediately, CTAB was used as second template to form prous structure in the silica shells. After the remove of inoranic CaCO3 and organic CTAB at alcohol/acid solution with ultrasonic assistant, a hollow mesoporous silica was obtained. A great of -OH were maintained by this template removing method, which performed an ideal platform for the adsorption of ibuprofen. This composite showed sustained release profile with ibuprofen as the model drug.Hollow calcium carbonate can be effectively used in the carry of large molecules owing to its biodegradable and large hollow structure. A series of hollow calcium carbonate have been reported, only a few hollow calcium carbonate with the particle size less than 500 nm were fabricated, of which the amount of product usually low. In view of these findings, we prepared hollow calcium carbonate (250nm-450nm) in the water/ glycol emulsion system. The morphology of products transformed from sphere to ellipsoid with the increase of amount of glycol.Mesoporous bioactive glass has been applied to repair bone defective and lost bone for decades. These days, researchers have paid attention to the synthesis of materials with specifical morphology and property. Mesoporous europium-doped bioactive glass spheres were successfully synthesized by a two-step acid-catalyzed selfassembly process in an inorganic-organic system. The results revealed that the IBU-loaded samples still showed red luminescence of Eu3+ under UV irradiation, and the emission intensities of Eu3+ in the drug carrier system varied with the released amount of IBU. The system demonstrates a great potential in the drug delivery and disease therapy fields.Calcium phosphate system has attracted significant interest for the good biodegradable. Many investigations displayed the original structure and functional property, however, there was few research focusing on porous-magnetic calcium phophate. Two Fe3O4 particles were prepared as magnetic core to react with Ca2+ and PO43-, giving the magnetic materials covering with calcium phosphate shell. Interestly, there are nanopores in both of the samples which can been separated easily at magnetic field. It is anticipated that the porous-magnetic calcium phophates may find advanced applications in target-drug delivery or selective adsorption/ separation of drugs etc.