| Tumor of bladder is the most common tumors of the urinary system, the vast majority of which come from epithelial tissue, and of which more than90%are transitional cell tumors. Tumor of bladder ranks fourth in men and tenth in women. The spread of the cancer heads to the bladder wall until involving the bladder tissue and adjacent organs. According to clinical habits, we refer Tis carcinoma in situ, papillary carcinoma of Ta non-infiltration and the lamina propria tumor of T1infiltration as superficial bladder cancers. General treatment of superficial bladder cancer is endoscopic laser or photodynamic therapy. To prevent the recurrence of tumor, intravesical infusion of drug can be used after treatment. The drugs commonly used are mitomycin, doxorubicin, HCPT, BCG and so on. Now it is generally considered that BCG works best. In infusion therapy process, due to the short duration of action, its efficacy is affect seriously, which result in multiple perfusion. High perfusion number and many other problems often bring patients a great deal of physical suffering and economic burden. Introducing of drug targeting adherent with sustained-release treatment bladder cancer treatment process, this study intends to design a new target sustained release integrated materials with BCG composite by freeze-dried BCG to make the BCG stay in the bladder more than48hours to attain effective solution to the above problem in a certain extent.Fe3O4belongs spinel ferrite, and its nanoparticles possess excellent superparamagnetic property. Firstly, Fe3O4nanoparticles were prepared by chemical coprecipitation. After aging treatment by heated in water bath, heated by microwave irradiation and hydrothermal, we analysis them with methods such as XRD, TEM, VSM. Using chemical coprecipitation method to prepare Fe3O4, Fe3+and Fe2+best ratio of1.75:1, the degree of crystallinity improve after curing Fe3O4grain, the grain size increases, the particle size of less than25nm; ratio of the saturation magnetization increases with the extension of the temperature or time of ripening; saturation magnetization and the degree of crystallinity of Fe3O4nanoparticles are higher after by hydrothermal aging treatment; after nano Fe3O4heat treatment at200℃water for4hours, Ms up to80.0emu/g. The He and Mr of Fe3O4treated with the microwave irradiation are small. And Ms, Hc, Mr were74.6emu/g,14.5Oe,2.02emu/g which irradiated for20min. Comparative data, we find that they have good superparamagnetic Fe3O4coprecipitation-prepared by microwave irradiation.Chitosan (CS) is deacetylated product of chitin. Because of its unique biological activity, biodegradability and biocompatibility, it has been widely used in industry, agriculture,medicine,and other fields.Chitosan-β-glycerophosphate(GP) thermosensitive hydrogel has good histocompatibility, non-toxic side effects in vivo biodegradable, which makes CS/GP temperature-sensitive hydrogels be widely applied to pharmacy, tissue engineering, and other fields. We put Chitosan-β-glycerophosphate thermo-sensitive gel as BCG and nano-magnetic ferrite carrier materials. We identified the preparation process parameters by study.90-100mg Chitosan with a deacetylation degree of95%was dissolved in4.5mL O.lmol/L of dilute hydrochloric acid, the400-500mg GP was dissolved in0.5mL of deionized water, and was added dropwise to the CS solution accompanied by stirring constantly. According to the different needs of adjusting the pH value in a37℃water bath, formation of a gel can be controlled within the time. Add the nano Fe3O4particles to the the chitosan in the thermosensitive gel preparation process, then dry and crush to get Fe3O4/chitosan thermosensitive hydrogel magnetic particles. SEM results show that, due to the gel viscosity and the hydrophobic interaction in the gelation process, Fe3O4produce more serious reunion, and the size of Fe3O4particle coated gel significantly increases. XRD and IR results show that Fe3O4didn’t react with gel matrix. Magnetic curves showed that the magnetic property of particles decline seriously, and Ms decreases by approximately80%, but the particles are still maintained a certain magnetic response characteristics and magnetic properties of the composite particles can be correspondingly increased with increasing the content of Fe3O4.Spectrophotometer method and the method of the tetrazolium salt (XTT sodium salt) are used to explore the detection method of BCG concentration. The freeze-dried BCG is white loose body powder, and uniform suspension after reconstituted. Its main components are the BCG, and its excipients include gelatin, sucrose, potassium chloride and monosodium glutamate. As the substrate of mitochondrial dehydrogenase, XTT is restored to the water-soluble orange formazan product by living cells. When XTT combines with the electronic coupling agent (such as PMS), the absorbance of water-soluble formazan product is proportional to the number of living cells. Experimental results show that simply detect BCG concentration by spectrophotometer, BCG solutions with different concentrations don’t have fixed absorption peaks. So the concentration of BCG can not be accurately measured. Due to its water-soluble color reaction, XTT sodium salt can reflect the vitality of cells, which can be applied to the vitality of detection of bacteria. The absorbance value and the BCG concentration of the solution showed a good linear proportional relationship. The XTT method will shorten the cycle of the detection of BCG concentration to24hours, which is simple.Adding Fe3O4and BCG to the chitosan thermosensitive gel in the the process of the preparation, and fully stirring to make the drug-loaded targeted sustained-release composite gel. We obtain BCG/Fe3O4/chitosan thermosensitive gel magnetic particles with high-speed mechanical crushing, and configure to release liquid perfusion. Then we explore the drug release properties of the BCG uploader magnetic composite particles. We take XTT method to detect the concentration of BCG release liquid. The results showed that in the early sustained release phase, a higher concentration can be achieved in a short period of time, and there is the "burst release" phenomenon. The concentration changes gradually stabilized after about12hours. And substantially maintaining a certain concentration to48hours, it has preferably sustained-release effect. Because of different drug loadings, the encapsulation efficiency of BCG drug first increased and then decreased with increasing drug content. When the drug content is10mg, the encapsulation efficiency is highest. Based on the diffusion theory, we modified the first class equation. And we put up with5parameters logarithmic slow-release model of targeted adherent integrated sustained release particles. For the5parameters logarithmic model as well as commonly used slow-release model, we conduct analysis and comparison from the simulation accuracy, variance, and forecast accuracy. The results show that the constructed function model can accurately reflect the release properties of the targeted drug particles.Using the same method, we prepared of BCG/Fe3O4/chitosan thermosensitive hydrogel target sustained release particles. Firstly, we conduct the vitro adherent experiments in the funnels. Inject the drug target sustained release particles suspension into the cone-shaped funnel, sway and shake. Putting NdFeB strong magnet close to the lateral wall of the funnel, we can find that the targeted magnetic drug-loaded particles can gather adherent to the side wall of the funnel. And there was clear solution in the funnel. After removed the external magnetic field, and shaked the funnel again, the targeted magnetic drug-loaded particles all discharged under the action of the flow. We take New Zealand white rabbits animal models to targeted release granules intravesical instillation, and detect by X-ray and CT. We can find that composite materials gathered in the bladder, and BCG/Fe3O4/chitosan thermosensitive hydrogel composite particles have good adherent effect. Every experimental group were put to death per24hours. Observing the BCG/Fe3O4/chitosan temperature-sensitive gel composite particles in the bladder, we can find that there are still a large number of composite material together after24hours, more material drain away with the urine after48hours, and there isn’t residual material in the bladder after72hours. The results show that the design of vitro strong magnet fixtures to ensure that the drug targeted sustained release composite particles in human bladder target adherent and maintain48hours is feasible and necessary. |
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