| Bone cancer is one of the serious diseases.Chemotherapy has been extensively utilized for killing bone cancer.However,the anti-cancer drugs not only kill the cancer cells,but also kill the normal cells.Photo-thermal therapy has been considered as a novel approach to kill the cancer cells.It is a minimally invasive treatment that induces tumor cells to overheat and kill it.Gold nanorod(GNR)is one type of typical photo-thermal materials and could effectively convert the near-infrared light to heat energy.However,GNR is also susceptible to agglomeration and the residual cetyltrimethyl ammonium bromide(CTAB)on the surface of GNR is cytotoxic.To overcome these disadvantages,immobilization of GNR on the material substrate would be advantageous for reducing their agglomeration and cytotoxicity.The ideal substrate should well mimic the structure and composite of bone extracellular matrix which is the nanocomposite of hydroxyapatite(HAp)and collagen.Gelatin is the degraded product of collagen and shows excellent biocompatibility and biodegradability.Compared with collagen,gelatin is much cheaper and easily available in a large-scale.Therefore,HAp/gelatin composites have been extensively utilized as bone regenerative materials.Especially,HAp/gelatin composite spheres are spherical in shape and present large specific surface area.They not only serve as the drug delivery system to control the release of anti-cancer drugs in chemotherapy,but also maximally fill in the irregular bone defects without morphological limitation and serve as bone regenerative materials to stimulate bone regeneration.Taking the advantages of GNR and HAp/gelatin composite spheres into account,in this thesis,the novel HAp/gelatin/GNR composite spheres were for the first time synthesized and their microstructure and NIR-sensitive photothermal property were evaluated.The main content of this thesis was described as below:(1)Firstly,HAp/gelatin composite spheres were synthesized by means of water/oil(W/O)emulsion method.The effects of HAp/gelatin mass ratio,the rotation speed,and the amount of emulsifier on the shape and size of the composite spheres were evaluated.The resultant composite spheres were characterized with an optical microscopy and scanning electron microscopy.The results showed that the size of the microspheres gradually increased.Most of the spheres were broken as the mass ratio was more than 5:1.Also,the size of the microspheres gradually decreases as the rotation speed was increased from 600 rpm to 1000 rpm.In addition,the addition of the emulsifier resulted in the decrease in size of microspheres from 100 ~500 μm to 40 ~ 50 μm.(2)Next,the drug delivery property and degradation of the HAp/gelatin microspheres were studied.The doxorubicin hydrochloride was used as a model drug and incubated with the composite spheres.The results showed that the HAp/gelatin composite microspheres supported the adsorption and release of doxorubicin hydrochloride with a controlled release profile.Also,the composite microspheres showed a good in vitro degradability.The degradation rate of the composite microspheres was dependent on the pH value of the solution and was higher at pH 4.5 than that at pH 7.4.(3)Finally,the HAp/gelatin/GNR composite microspheres were synthesized and their microstructure and NIR-sensitive photo-thermal property were evaluated.The composite microspheres were characterized by Fourier transform infrared spectroscopy,X-ray diffraction,transmission electron microscopy and scanning electron microscopy.The results showed that the HAp/gelatin/GNR composite microspheres were successfully synthesized and presented excellent NIR-sensitive photo-thermal property.With the increase of the irradiation time of near-infrared light,the temperature increased gradually within 12 min.The concentration of the rod also has a significant effect on the heating effect.With the increase of the concentration,the temperature difference of the temperature changes after the 12-minute irradiation process. |
