Experimental Study On The Biological Capability Of The Nano-hydroxyapatite/polyamide66 Composite And Repairing Bone Defect With The Porous Composite

It is well known that hydroxyapatite (HA) is a biocompatible material with good osteoconductivable properties. It has been known that HA can promote early bone ingrowth. However, this bone substitute is mechanically weak and its particles might migrate from the site of the implant .Recent development in nanotechnology provides new properties to medical biomaterials, which make it stronger mechanically. So does a new type of inorganic-organic biomimetic component including nano-hydroyapatite (n-HA) and polyamide66 (PA66) composite (n-HA/PA66). Results of the test and analytical studies indicated that the distribution of n-HA homogeneously in polyamide matrix nanograde needle-shape apatite crystals of n-HA was similar to bone apatite. Polyamide66 has long history of using in clinical field with a good compatibility. The purpose of our study is to evaluate the biocompatibility and biological security and bioactivity of the composite in vivo and in vitro; Study the osteoconductivity and the ability to repair bone defect with the porous composite. This study have three separate parts. (1)Study the biocompatibility and biological security of the n-HA/PA66 composite in vivo and in vitro. (2) Study the bioactivity of the n-HA/PA66 composite and the effects it would be to body's metabolism of calcium and phosphorus ion in vivo. (3) Study the osteo-conductivity and the ability to repair bone defect of the porous n-HA/PA66 composite and the feasibility use it as the scaffold of bone tissue engineering. Objects and Methods as follows: 1.To evaluate the biocompatability of nano-hydroxyapatite crystals and polyamide composite (n-HA/PA66) with the L929 cells.To proceed the morphological observation and take pictures of L929 cells after 1d,2d,4d,and 7d of co-cultured with extract of n-HA/PA66 ,and direct contact with n-HA/PA66.To determine light absorbtion value of every hole under 500 nm with enzyme linked immunity instrument after 1 d,2 d,4 d,and 7 d of contact of n-HA/PA66 extract with L929 cells,and direct contact with n-HA/PA66.In the meanwhile calculate the relative multiplication rate of cells,and evaluate them by six degree tests for cytotoxicity. To investigate the acute and chronic toxic reaction on the whole body induced by the new nano-hydroapatite crystals and polyamide composite(n-HA/PA66)after implanting in vivo and its effects on partial constitution of animal organs after implanting in vivo,and evaluate the potential and degree of subcuticular stimulation reaction.According to the evaluates criteria of medical implantted materials,biology and animal trial recommended in GB/T16 886.5-1997-ISO10 993-5:1992, The n-HA/PA66composite were implanted into the muscle and bone tissue of rabbit ,blood was drawn at different point .General and histochemical examanations of blood were performed at different points.The inflammation index,the biochemical index of blood and functional indexes of liver and kidney were tested by use of Beckman automatic biochemical analysis device,to evaluated the acute toxic on the whole body.On the other hand,the specimens were harvested at different point respectively and examined by histology ,to evaluate the tissue response to the composite , after implantation 6 months,the rabbit's liver and kidney were harvested examined by histology .Diffusion solution at different concentrations was added into the sample of animal blood to measure each absorbance with spectrophotometer and work out the corresponding rate of haemolysis .The primary irritation index (PII) was worked out after observing at the rate point by subcutaneous injection into the back of animal. Injected the extract of n-HA/PA66 in abdominal cavity to perform micronucleus test in marrow smear; Putting salmonella bacterium and the extract of n-HA/PA66 into culture vessels to perform Ames test. 2.To investigate the bioactivity of nano-hydroapatite crystals and polyamide composite (n-HA/PA66), and the effects it would be to body's metabolism of calcium and phosphorus ion .The n-HA/PA66 composite were implanted in rabbit?...