RESUMEN
BACKGROUND:Bone transplantation is the only method for the repair of bone defects. However, traditional bone transplantation has some disadvantages. Bone tissue engineering, as a new treatment strategy, can achieve the desire therapeutic outcomes. OBJECTIVE:To fabricate a new tissue-engineered scaffold for improving bone repair effectively. METHODS:Hydroxyapatites (HA) with different Ca/P (1.50/1.67) ratios were synthesized by chemical precipitation method and microwave radiation method. Composite scaffolds of palygorskite (APC)/HA/polycaprolactone (PCL)/col agen (COL), APC/calcium deficiency HA (CDHA)/PCL/COL, and APC/PCL/COL (control group) were prepared by solution perfusion-solvent evaporation and ion leaching method. The material characterization, active ingredients, hydrophilic property, and mechanical properties were evaluated by scanning electron microscope, infrared spectrometer, surface contact measuring instrument and universal mechanics, respectively. The histocompatibility of the implant with the host was assessed through animal experiments. RESULTS AND CONCLUSION:By precise control of pH range, HA with different Ca/P ratios could be synthesized. The mechanical properties, air permeability, hydrophilic property of the APC/HA/PCL/COL and APC/CDHA/PCL/COL composite materials were significantly increased compared with the APC/PCL/COL composite material (P<0.05), while the porosity, water absorption expansion rate were significantly decreased (P<0.05). Results from our animal experiments showed that no immune inflammatory reaction was observed suggesting that the composite materials hold good histocompatibility. To conclude, the APC/HA (1.50/1.67)/PCL/COL composite materials are promising bone substitutes in bone tissue repair.
RESUMEN
Through comparing students' achievements of one-teacher-responsible teaching and multi-teacher-responsible teaching,we found that students' achievements of one-teacher-responsible teaching were significantly higher than those of multi-teacher-responsible teaching(P