Construction Of Multilevel Microsphere Scaffold Which Load And Control Release Anti-tuberculosis Drug

Bone tuberculosis is a purulent and destructive lesions, caused by the tubercle bacillus invading into the osseous tissue. At present the clinical treatment is generally surgical excision of the lesion necrotic tissue and then sprays with drugs to clear the residual tubercle bacillus. But the drug spraying within the organization will soon be washed away by body fluids, so the patients need several operations to spray the drugs, which will increase the suffering to the patients. The shortcomings of oral medication are the useful capacity of drugs is very few, and the drug exploitation degree is very low and causes the first pass effect of hepar and resistance, etc. The leading anti-tuberculosis drugs are rifampin, isoniazid, ethambutal, pyrazinamide, and streptomycin. Because each drug has different damage effects to the tubercle bacillus, they are used together on clinic, which have better pesticide effect to kill the tubercle bacillus.In recent years, drug delivery system (DDS) slow system remediation and bone tissue engineering scaffolds are focus research at home and abroad. Combining both DDS and the TE, which is implanting DDS into the TE, the drug in the carrier can be control released sustainly, stably and efficiently, so as to repair the bone defect and drug therapy. Therefore we have to design a multi-stage microspheres stents for the resistance of osseous tuberculosis and control release drugs. The fist carrier medicine is made of hydroxyapatite, mesoporous silica, the outside coated by poly lactic acid, poly hydroxyl ethanol acid (PLGA). The second control-released carrier is composite microspheres both organic polymer and inorganic powder. Then through the sintering, the microspheres were bonded together to form three dimensional connected duct scaffold materials, which is the third level of control-released carrier.The paper is divided two parts to construct microspheres scaffold for the resistance of osseous tuberculosis. On one hand, from the point of bone repair, four microspheres were prepared: PLGA, HA-PLGA, HMS-PLGA and (HA: HMS = 1:1-PLGA), and four stents were also prepared. The [(HA: HMS = 1:1)-PLGA] microspheres scaffold has the best mechanical properties in three scaffolds, whose compressive strength can approach 7.2 MPa; while HA-PLGA microsphere scaffold isonly 0.38 MPa. At the degradation process, the pH value of HA-PLGA microsphere scaffold falls at least, but the (HA: HMS= 1:1-PLGA) microsphere scaffold has the biggest decline, and it has the greatest quality loss. After six weeks degradation, all of the scaffolds had obviously volume expansion.On the other hand, from the point of controlled release of DDS, we prepared the first level controlled release system: HA-INH, INH-HMS and RFP-HMS, respectively prepared their corresponding drug loaded microspheres. We also investigated the drug release behavior in PBS, and found that all sorts of drug loaded microspheres, had a Cumulative release about 80% of the total explosive in 50 days, and the morphology of microspheres were entire sphere.