Nanostructured Metal Phosphates:Controllable Synthesis And Biological Property

Metal phosphates have received much research attention due to their properties useful for catalysis, ion exchange, proton conductivity, intercalation chemistry, photochemistry and bioresearch. Controllable synthesis of metal phosphates, however, is rarely reported, presumably due to their rather complicated crystal structure and easy crystallization in solution. Metal phosphates in nanoscale, such as hydroxyapatite nanotubes, aluminophosphate nanorolls, copper hydroxyphosphate nanotubes, crystalline mesoporous nickel phosphates with nanotubular structure, etc. have been synthesized by chemical precipitation method:using mixed organoamines with long-chain to precipitate metal phosphates and control their morphologies. By characterization techniques of Powder X-ray diffraction (XRD), Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM), Scanning electron microscopy (SEM), nitrogen sorption, thermogravimetric analysis (TG/DSC or TG/DTA), inductively coupled plasma atomic emission spectrometer (ICP), UV-Vis diffuse reflectance spectra (UV-vis), FT-IR spectra(FTIR), etc. their morphologies, sizes, structures and compositions were well characterized. The main results are summarized as follows:1. High quality hydroxyapatite nanotubes:synthesis and their enhancement for osteoblast proliferationSingle crystalline hydroxyapatite nanotubes have been synthesized by a hydrothermal method from calcium dihydrogen phosphate, calcium chloride and mixed organoamines of dodecylamine and hexadecylamine. The synthetic mechanism for the nanotubes was followed by careful observation on the evolution of the morphology and crystal phases of products in the synthetic process. A mechanism accounting for two step phase transformations among the calcium phosphates family has been revealed:Firstly, rectangular plates of dicalcium phosphate dihydrate (CaHPO4·2H2O) formed by the slow liquid reactions disintegrated to nanorods or nanofibers of dicalcium phosphate (CaHPO4). Secondly, the nanofibrillar DCP transformed to hydroxyapatite nanotubes. It is discovered that the nanotubes can boost osteoblast proliferation in vitro, which is important to significantly reduce the bone repair time.2. Biomimetic synthesis of aluminophosphate nanorolls induced by mixed organoaminesAluminophosphate nanorolls have been synthesized by a biomimetic synthesis method in principle. In the synthetic process, mixed organoamines of dodecylamine and hexadecylamine are used as mineralizer and template to mineralize and control aluminum chloride and sodium dihydrogenphosphate to form aluminophosphate nanorolls. By TEM and XRD analysis, it is revealed that the inorganic-organic hybrid nanorolls have layered structures consisted of kingite and organoamines. The formation of aluminophosphate nanorolls is a scrolling formation mechanism.3. A simple and general approach for the synthesis of multicomponent Cu2(OH)PO4 nanotubesNanotubes of multicomponent Cu2(OH)PO4 have been synthesized by a hydrothermal method from ammonium dihydrogenphosphate, copper chloride and mixed organoamines of dodecylamine and hexadecylamine. The synthetic mechanism for the nanotubes was followed by careful observation on the evolution of the morphology and crystal phases of products in the synthetic process. A mechanism has been revealed:from vesicles to tube-like structures like those organic aggregations behaving in solutions.4. Synthesis of crystalline mesoporous nickel phosphates with nanotubular structureCrystalline mesoporous nickel phosphates with nanotubular structure have been synthesized by a hydrothermal method from ammonium dihydrogenphosphate, nickel chloride and mixed organoamines of dodecylamine and hexadecylamine. By TEM, XRD and BET analysis, it is revealed that crystalline nanodomains disperse in the walls of the tubular pores in the nickel phosphates. By careful observation on the evolution of the morphology and crystal phases of products in the synthetic process, it is discovered the mesostructures are transformed from lamellar structures composed of mixed organoamines and nickel phosphates. At the same time, the amorphous walls transform crystalline walls.5. Controllable synthesis of nano-Metal phosphates (Ce, Nb, V, Sc and LiFe)A series of metal phosphates in nanoscale, such as crystalline mesoporous cerium phosphate, crystalline mesoporous niobium phosphate, lamellar vanadium phosphate, scandium phosphate nanocubes and lamellar lithium iron phosphate, etc. have been synthesized by a hydrothermal method from ammonium dihydrogenphosphate, soluble salts of matal and mixed organoamines of dodecylamine and hexadecylamine. Their morphologies, sizes, structures and compositions were well characterized by characterization techniques of XRD, TEM and BET, etc.