Novel Drug Carrier Systems Based On Nano Hydroxyapatite Materials

With the development of modern medical technology and materials science development, especially, the emerging area of inorganic nanoparticles entrapping biomolecules has already exhibited its diversity and potential applications in many frontiers of modern material science. Some of the novel inorganic carriers for gene drug delivery have been a hot spot in the field of medicine transportation in recent years such as gold nanoparticles, silica nanoparticles, calcium phosphate nanoparticles, manganous phosphate nanoparticles and other inorganic phosphate nanoparticles. The calcium phosphate nanoparticles could translocated into cells because it had good biocompatibility, bioabsorbability and biodegradability, lack toxicity and stable chemical properties, on the other hand, it also could be exploited to deliver a broad range of therapeutics including proteins, antibodies, oligonucleotides, imaging agents and liposomes in a variety of situations and biological systems. Calcium ions of calcium phosphate carrier can form chemical bond with phosphate backbone groups of antisense oligonucleotides (ASODNs), it's one of the efficient methods for protecting ASODNs transfer into cell lines, drug carrier loaded antisense drugs can be selectively concentrated in cancerous site to reduce drug degradation and losses, reduce drug cytotoxicity to normal cells or tissue and improve drug availability.In this study, we used the double reverse emulsion approach to prepare the ASODNs loaded into calcium phosphate nanoparticles as gene delivery system for achieving high efficiency transfection in HeLa cell lines. it provided a main research direction for structure new antitumor drug carriers and improved the efficiency of drug utilization. For further study, it considered magnetic contrast agent composite with hydroxyapatite to prepare fluorescent marker and magnetic imaging function of multifunctional nanoparticles, this provides a research direction for the developmentof multifunctional drug nanoparticles. This paper includes three part contents as follows:1. The first part content mainly discusses preparation of nanometer hydroxyapatite with aqueous phase method. The results show that it has succeed for preparing nanoscale spherical hydroxyapatite nanoparticles. In vitro cytotoxicity studies of hydroxyapatite nanoparticles using the MTT assay with HeLa cells to cytotoxicity, the results show hydroxyapatite have a good biological safety in a certain concentration range of concentration.2. The second part content mainly discusses calcium phosphate nanoparticles as carriers for efficient cellular delivery of antisense oligodeoxynuclecotides. In this study, we used the double reverse emulsion approach to prepare the ASODNs loaded into calcium phosphate nanoparticles as gene delivery system. Calcium phosphate coprecipitation is one of the most common methods for successful preparation of ASODNs-CP nanoparticles, because divalent metal cation Ca2+ can bind phosphate backbone groups of antisense oligodeoxynucleotide. We successfully preparation ASODNs-CP nanoparticles and this drug carrier system have a high loading efficiency and improve transfection and anti-cancer efficiency by the characterizations of uv-vis spectra, fluorescence spectrum, TEM, MTT method and flow cytometry. ASODNs-CP nanoparticles can be truly effective promote HeLa cells apoptosis by using laser confocal microscopy, biological microscope.3. The third part preliminary exploration of researching the manganese contrast agent- ASODNs-hydroxyapatite composites preparation and characterization, it was charactered by TEM, LSCM and vibrating sample magnetometer, the results showed that we successfully prepared dispersible multifunction contrast magnetic agent imaging nanoparticles which have a certain relaxation rate and fluorescence effect. This study for the development of new-type multifunctional magnetic agent imaging provides a new method and idea.