Preparation And Properties Of Calcium Phosphate Composites

Due to its excellent biocompatibility,osteoconductivity and similar to inorganic components of natural bone,calcium phosphate materials(Ca Ps)have been taken great attention in recent years.Most of Ca Ps are widely used as biomedical materials,including bone fillers,bone tissue engineering scaffolds,bioactive coatings and composites.Furthermore,Ca Ps are potential carriers for drug/protein/gene delivery,and also can be used as cell targeting,fluorescent labeling,imaging and diagnostic materials.In addition,in mimic biomineralization processes they were used as model compounds.However,the disadvantages of easy aggregation and poor mechanical properties limit Ca Ps for further applied.Studies shown that these defects can be compensated by combining Ca Ps with various inorganic/organic materials.Here,a composite material with spherical structure and uniform surface crystal dispersion which use liquid paraffin(LP)and Ca Ps as raw material was prepared in a emulsion-coprecipitation method;a composite material with special structure and good dispersion of Ca Ps crystals was prepared by liquid paraffin,polyethylene glycol(PEG)and Ca Ps by emulsion-template-coprecipitation method;a composite with temperature and p H sensitivity was prepared by hydroxypropyl cellulose(HPC),sodium alginate(SA)and Ca Ps.Several kinds of characterization methods were used to analyze the structure,morphology and element distribution of the above products,such as Fourier Transform Infrared Spectrometer(FT-IR),Thermogravimetric Analysis(TG),Scanning Electron Microscope(SEM),and X-ray diffraction(XRD).The best method to prepare composite materials was also investigated.In addition,the properties of the prepared materials for drug loading and release,temperature and p H responsiveness were also investigated.This paper mainly includes the following parts:1.Firstly,the meaning and characteristics,their role in human body,and the current application of Ca Ps materials in different fields was introduced.Secondly,according to the Ca/P ratio,the structure and properties of different types of Ca Ps were described respectively.The third,advantages and disadvantages of different synthetic methods of Ca Ps were summarized.Finally,hydroxyapatite(HA)was used as an example to briefly summary the preparation and properties of composite products that prepared by Ca Ps and different types of inorganic/organic materials,the disadvantages such as poor dispersibility and poor mechanical properties can be improved by Ca Ps combined with different materials which can provide Ca Ps broad application prospects.2.HA is one of the most important Ca Ps.In this chapter,HA was selected to prepare composite by emulsion and coprecipitation method.Firstly,Liquid paraffin was used as raw material,and a liquid paraffin microemulsion was prepared whichcan provided micro droplets.Subsequently,HA crystals were deposited on the surface of liquid paraffin droplets by in-situ precipitation to prepare HA composite paraffin material(HA/LP).Using IR,TG,XRD and SEM to characterize the structure and microstructure of the composites.It was found that the HA/LP have a regular spherical structure,and the HA crystals were evenly distributed on the surface,which can effectively improve the shortcomings of HA aggregation.The loading and release properties of HA/LP on the RB were tested.The results shown that the composite provided with sustained release property and p H response to the drug.3.Based on the emulsion-precipitation method,the synthetic polymer material PEG was added as a co-emulsifier and template to prepare microemulsion,and HA crystals was formed on the PEG template by a precipitation method.As a result,composite material(HA/PEG/LP)were prepared by HA,PEG and LP.The composition,microstructure and element distribution of HA/PEG/LP were characterized by IR,TG,XRD,SEM and EDS.It was found that the HA/PEG/LP shown a regular special structure,and the crystals are evenly distributed on the surface of HA/PEG/LP.The loading and release properties of the composite to RB were tested,and the results shown that HA/PEG/LP provide a certain sustained release property and p H responsiveness to the drug.4.Ca P was deposited on the polymer chain of hydroxypropyl cellulose(HPC)to prepare Ca P@HPC by in-situ precipitation,HPC is a temperature sensitivity material and used as a framework material in this chapter.Subsequently,dispersion of Ca P@HPC was added into the SA solution and being freeze-drying to prepare a composite material(Ca P/SA/HPC)which with responsiveness to temperature and p H.Composition,microstructure and elemental of Ca P/SA/HPC were characterized by IR,TG,XRD,SEM and EDS.The product was looked like a sponge with a large number of white thin layers which cross-linked to each other,and there are a large number of nanoparticles in the fault.The mechanical properties,responsiveness of temperature and p H of the composite were also investigated.Results shown that the material have a certain elasticity and sensitive to temperature and p H.The loading and release properties of Ca P/SA/HPC to Tetracycline Hydrochloride were investigated.Results shown there is a high loading rate and release rate and a certain sustained release effect of Ca P/SA/HPC to drug.Furthermore,the release rate is response to temperature and p H.In summary,composite materials with different morphologies and structures were prepared by Ca P with different organic materials.The composite material prepared by the emulsion method have regular morphology,uniform crystal distribution,the disadvantage that Ca Ps are easy to aggregate was also improved.The composite materials can be used as a drug carrier with sustained release and controlled release properties.The composite that use Ca P as filler was provide properties of shape memory,temperature and p H responsiveness,and can be used as a smart material in biomedical fields such as tissue engineering and so on.