Synthesis Of Functional Calcium Phosphate Nanocomposites And Its Drug Controlled Release Properties

The ideal drug controlled delivery system requires not only good biocompatibility and high loading rate, but also the characteristic of zero release of drug molecules in the blood circulation. Nano-biomaterials are the very promising and popular candidates because of their biocompatible and nanometer properties. which have been widely used in biomedical applications. Due to its outstanding biocompatibility and high stability, synthetic hydroxyapatite (HAP) has been considered as excellent candidates for biomedical applications. Biomineralization principles can guide us to construct artificial multifunctional materials with mesoscopic to macroscopic hierarchically ordered structures. In the present work, amphiphilic phosphoproteins-controlled formation of hydroxyapatite and it’s application in drug release will be investigated. This will contribute to not only understanding the biomineralization mechanism deeply, but also providing new theoretical guidance and design basis for nano-biomaterials synthesis. The following are some main results from our work:(1) HAP/casein nanocomposite was synthesized through coprecipitation method under the control of casein. The products were characterized by transmission electron microscopy (TEM). X-ray diffraction (XRD). Fourier Transform infrared spectroscopy (FTIR). and thermogravimetric (TG) measurements. The results show that HAP@Casein composite nanoparticles exhibit spherical porous structure. Casein not only has a stabilizing effect on nanoparticles but also provide the hydrophobic region for nanoparticles. The loading characteristics of hydrophobic drug, morin. to nanocomposites were further investigated by infrared spectroscopy. UV-Vis spectroscopy and fluorescence quenching methods. The experimental results reveal that the HAP/casein nanocomposites have a high morin loading capacity and pH-controlled drug release function. Thus, the as-prepared HAP/casein nanocomposites are promising for hydrophobic drug adsorption and pH-controlled drug release applications.(2) Protein with both phosphate groups and acid amino acid residues can control the mineralization of hydroxyapatite more specially. In the presence of casein stabilized Fe3O4 casein and urea can control the formation of flower like HAP@casein(?)Fe3O4 nanocomposite cooperatively. By changing the synthesis conditions, such as reaction temperature, ion concentration, urea concentration, casein concentration and reaction time, the crystallization of hydroxyapatite was investigated deeply. The interaction between phosphate group of casein and calcium ions, the amphiphilic property of protein and the cooperative interaction of casein and urea play critical roles in the formation of flower like HAP(?)casein(?)Fe3O4 on the microscopic level. The further experimental results reveal that the HAP(?)casein(?)Fe3O4 nanocomposites have a high DOX loading capacity and pH-controlled drug release function.(3) Tumor therapy has been a difficult problem in medicine. The drug loading system with double drug loading can enhance the therapeutic effect, and become a hot spot in cancer therapy. The presence of both casein and protamine can control the formation of sponge like HAP(?)casein nanocomposite cooperatively. By changing the synthesis conditions. such as reaction temperature. ion concentration. urea concentration. casein concentration and reaction time, the crystallization of hydroxyapatite was investigated to obtain the formation mechanism. The interaction between phosphate group of casein and calcium ions. the amphiphilic property of protein and the cooperative interaction of casein and protamine play critical roles in the formation of flower like HAP@casein on the microscopic level. Using DOX and morin as model drugs, the loading characteristics of two different drugs to nanocomposites and the release properties were further investigated. It was found that the HAP@casein nanocomposites have high loading capacities towards the two drugs and pH-controlled drug release function. These results indicated that the HAP@casein could be used as a promising drug controlled delivery system and may find great potential applications in biomedicine area.