Experimental Study Of Nano-bone Adhesive

【Objective】As the development of traffic and bungee construction, the incidence of serious extremities fracture is increasing gradually, in which the treatment of grievous comminuted fractured is still the field of orthopeadics to be one of challenges at present. The traditional internal fixation that could lead to non-union,delayed union and malunion of bone, even permanent disability to patients is hard to satisfy. Nowadays, the difficult and hot spots are histological engineering combined with nanotechnology to research the internal fixation materials in clinic to crue the stress communited fracture. Our project is based on the modified synthetic technology ofα-Butyl cyanoacrylate, by nanotechnology, mixed with nanometercatalyst and nCS. Researched from adhesive strength and biodegradation rate, these features of bone glue are improved. Recombined with osteoinductived icartin, the absorbable and osteoinductived macromolecule nano-bone adhesive with both characters-fixation and osteoinduction has been manufactured. This task could resolve the critical technical issues of existing bone adhesive, such as low viscosity, weak mechanical property, less easily absorbtion and without osteoinduction. Fixation bone fragments with this mighty glue will be a new method of comminuted fracture and bring some grand social effect and economic benefit.【Methods】1. Glue prescription(1) Observed that the glue mixed with nCS powder congeal instantly or not;(2) Texted the agglutinate character using animal bone and compared with the adhesive strength of some kinds of glue with different concentration;(3) Choosed the best bone glue by statistical analysis for experiment in vivo and vitro. 2. The cytotoxicity experiment Rabbit bone marrow stromal stem cells were directly implanted with nano-bone adhesive and common medical glue, the growth of these cells on the surface of the two glues was observed by inverted microscope and scanning electron microscope. The extracting solution of the two glues was collected to culture cells. At 0, 6, 12, 18, 24 hours (short-term assay, viability) and 1-7 days (long-term assay, survival), the cells were examined everyday. Standard polyvinyl chloride tubes were cohered by the two glues respectively, to compare their adhesive strength. Their consolidation time on different contract surfaces was also accounted.(1) Glue planked and cells implanted;(2) Monitored the concentration of some substance delivered from the glue at different time spot by HPLC;(3) The extracting solution of the two glues was collected to culture cells. At 0, 6, 12, 18, 24 hours (short-term assay, viability) and 1-7 days (long-term assay, survival), the cells were examined everyday;(4) Observed the growth of these cells on the surface of the two glues by SEM;(5) Tested the adhesive strength and compared the consolidation time.3.Animal experiment(1) Divided into five groups according to different constituents of the glue (two kinds of additive mixed with pure glue):(2) Operated 50 rabbits to make the models of bilateral ulnas fracture and fixed with 5 groups glue respectively.(3) At afteroperation, X-ray performed every 2 weeks in 2-12 weeks and put the rabbits to death at 2nd week, 6th week, 8th week and 12th week to carry out biomechanical analysis, microCT scanning and histopathology study.【Results】1. Glue prescription(1) Blended nCS and pure glue could lead to a well-distributed auspended matter. The nCS powders will not concrete and with the concentration increasing, the mixture was still liquid state and viscosity didn't change;(2) Agglutinate character: the consolidation time of adhesive of different glues were not significant difference, and the biomechanical presents a parabola with the nCS increasing. When the concentration was 10%, the most average adhesive strength took on.2. The cytotoxicity experiment(1) After three times of culture medium replacement, the cells can be grow on the surface of nano-bone adhesive and medical glue. Both had some cytotoxicity that was not significant difference.(2) The mechanical strength of nano-bone adhesive was stronger than the medical glue, and the consolidation time of the former was also faster than the latter.3.Animal experiment(1) X-Ray, histopathology showed that at 12th week, unlas fracture of GⅠand GⅤhave healed and medullary cavity have been unobstructed, however, GⅢand GⅣhave not healed completely, inferior than GⅠand GⅤ. The delayed union took placed in GⅢ.(2) At 6th week, microCT took on that bony callus around fractures of GⅠand GⅤis at most, inferior in GⅢand GⅣ, least in GⅡ.(3) Biomechanical strength of GⅠand GⅤis not significant difference at 12th week, but stronger than GⅢand GⅣand GⅡis the weakest. 【Conclusion】1. The strongest adhesive strength is that the concentration of nCS in nano-bond is 10%.2. The cytotoxicity of modified nano-bone adhesive is not higher than the medical glue, but the mechanical strength and consolidation are more superior. The former also can stimulate the ossification.3. The nano-bone adhesive can't lead to fractures delayed union; Compared with traditional medical glue, its mechanical strength is stronger and it will promote fracture healing. So, the nano-bone adhesive is expected to become an ideal material for repairing bone fracture, and get extensive application in clinic.