Preparation And Properties Of Rare Earth/Chitin Composite Bone Implant Material

Good bone implant materials need to meet the requirements of mechanical support,biodegradability,bone conductivity,no cytotoxicity and biological activity.Natural polymer based bone implant materials are a kind of biomaterials with three-dimensional network structure,which are mainly composed of natural polymers and formed by physical/chemical crosslinking or polymerization.They have good biocompatibility and bioactivity.However,a single polymer material has some disadvantages,such as mechanical mismatch and limited functionality,which limits its application in clinical bone repair.Therefore,how to prepare more ideal bone implant materials through condition optimization and material composite,and comprehensively improve its mechanical support,traceability and biological activity is a difficult problem faced by orthopaedic implant devices.Firstly,this paper takes ?-Chitin bone scaffolds were prepared by low temperature freeze-thaw method with chitin powder as raw material and 12 wt% Na OH/4 wt% urea aqueous solution as solvent.The preparation conditions with better mechanical properties were determined by exploring the preparation conditions,such as chitin content and particle size,ultrasonic time/power,freeze-thaw time and so on.The preparation conditions were determined as follows: the content of chitin was 10 wt%,the particle size was 200 mesh,the ultrasonic time and power were 30 minutes and 80 W respectively,the freeze-thaw days were5 days,and the compressive strength was about 2.6 MPa.Secondly,the effects of natural polymer materials(sodium alginate,silk fibroin,gelatin,microcrystalline cellulose,starch,etc.)or rare earth micro nano materials on the mechanical properties of chitin scaffolds were studied.Among the natural polymers selected,the composite material was gelatin with the addition amount of 1.5 wt%,the compressive strength of the composite scaffolds could reach 4.3 MPa and the water absorption was 198%.When gadolinium phosphate is added,the amount of gadolinium phosphate is 0.1 wt%,the compressive strength of the composite scaffold can reach 3.9 MPa and the water absorption is 191%.In order to further increase the mechanical properties of the scaffold,we compounded0.1 wt% gadolinium phosphate and 1.5 wt% gelatin with chitin at the same time,soaked the composite scaffold in 45 wt% glycerol solution and washed it to neutral with deionized water.It was found that after compounding the three substances,the compressive strength of the scaffold tested by universal testing machine could be increased to 6.2 MPa.At the same time,the crystal structure of the scaffold was analyzed by X-ray diffraction(XRD),the chemical groups of the scaffold were analyzed by Fourier infrared spectroscopy,the surface morphology of the scaffold was observed by scanning electron microscope(SEM),and the thermal stability of rare earth/gelatin/chitin composite bone scaffold was studied by thermogravimetry differential thermal analysis(TG-DTA).Finally,we explored the effects of different drying methods on the mechanical properties of chitin scaffolds.The chitin scaffolds soaked in absolute ethanol were soaked in deionized water after vacuum drying or freeze-drying;The former is of little help to improve the mechanical properties of the support,while the latter will decline.The mechanical properties of scaffolds treated with 45 wt% glycerol solution were significantly improved after drying and then soaking in deionized water.The mechanical properties of gadolinium phosphate/gelatin/chitin composite scaffolds were significantly improved,up to 17.3 MPa.The support is vacuum dried at the temperature of-0.1 MPa(37 ?-45 ?),and the shape of the support is uniform,which can form a central macropore structure.