Preparation And Properties Of Polyurethane Composites Reinforced By Antibacterial Nanodiamonds

Biomaterials in the form of implants are widely used to replace and/or restore the wounded and damaged tissues and organs,thereby improving the quality of life of patients,especially bone tissue repairing implants.However,the use of implants presents a number of problems,including bacterial infections,high cytotoxicity,and significant mechanical differences between the implant and the host organ.Biodegradable polyurethanes are widely used in the bone tissue-repairing field due to their excellent physical and chemical properties.With the development of nanotechnology,nanodiamonds with super hardness,surface modification and biocompatibility are also widely used in biomedical fields.In this paper,polyurethane composites reinforced by antibacterial nanodiamonds were prepared,which had the characteristics of resisting bacterial infection,mechanical property and suitable degradation rate.1.In this paper,different proportions of cationic polymer functionalized nanodiamonds(QND)were added to the polyurethanes to prepare polyurethane composites(APU,APU/0.5%QND,APU/1%QND,APU/1.5%QND).Then,the thermal stability,crystallinity,mechanical properties,antibacterial properties,hydrophilicity,degradability and biocompatibility of the polyurethane composites were evaluated comprehensively.The results showed that 1% amount of functionalized nanodiamonds can be uniformly dispersed in the polymer,and 1.5% of the modified nanodiamonds showed agglomeration in the polymer.The prepared composites had excellent thermal stability.The crystallization behavior,mechanical properties,hydrophilicity and degradation rate of the polyurethane composites can be improved by addition of the dispersed nanoparticles into the polyurethanes.Therefore,the overall performances of the polyurethane composites were excellent with the addition of 1% QND.Not only the mechanical properties were improved,but also the bacterial adhesion was reduced.At this concentration,the cytotoxicity of the composites met clinical application requirements.2.In order to improve the hydrophilicity and antibacterial property of the polyurethane composites,the experimental process has been improved.First,the starting material poly(?-caprolactone)diol in the preparation of polyurethanes was replaced with mixed diol(poly(?-caprolactone)diol and polyethylene glycol,molar ratio of 9:1).Silver/polycation-modified nanodiamonds(QND-Ag)were used as reinforcing particles.Using the same method,polyurethane composites(APU(10%PEG),APU(10%PEG)/QND,APU(10%PEG)/QND-Ag)were prepared respectively.The results showed that the crystallinity and mechanical properties of APU(10%PEG)were reduced correspondingly with the addition of PEG.But due to the combined effect of PEG and QND-Ag,the mechanical properties of APU(10%PEG)/QND-Ag were improved.The degradation rate of the composites were enhanced by the addition of PEG and QND-Ag,which tailored the healing rate of bone tissue.Compared with APU/QND,antibacterial abilities of APU(10%PEG)/QND-Ag were improved significantly,which possessed dual-antibacterial abilities of contact and release.The cytotoxicity test showed that the cell survival rates of the osteoblasts that cultured on the surface of the composites were more than 80% after 7 days,showing good biocompatibility.Therefore,the prepared APU(10%PEG)/QND-Ag has more excellent mechanical properties and antibacterial properties,which is more promising for use in the field of bone repairing.