Preparation And Application Of Polyurethane Foam Dressing For Nasal Packing

Chronic sinusitis is one of the most common chronic diseases,and its important treatment method is functional endoscopic surgery.Good nasal packing materials can greatly reduce postoperative bleeding,inflammation,infection and other complications.However,the high-quality packing materials used in clinical practice in China are mainly foreign products.In this thesis,degradable polyurethane foam(PUF)with good mechanical properties and liquid absorption capacity was prepared.Then,natural chitosan(CS)and quaternized chitosan(QCS)were used to replace the traditional small molecule chain extender,glycerin,and a degradable polyurethane foam dressing with antibacterial and biocompatible functions was successfully developed for nasal packing1.Biodegradable hydrophilic polyurethane foam PUF was successfully prepared from polyvinyl alcohol(PVA),polycaprolactone diol(PCL-diol)and aliphatic hexamethylene diisocyanate(HDI)by prepolymer method.The formula of the foam sample PUF-control optimized by orthogonal design was:30 g polyurethane prepolymer,10 g water,0.6 g glycerin,0.12 g DBTDL,0.05g TEDA and 0.6 g L-580.Under this formulation,polyurethane foam products had no defects and were characterized by low density(0.093 g/cm~3),high water absorption(17.34 g/g)and softness(compression strength at 30%strain was10.3 k Pa).2.Based on the formulation of PUF-control,PUF-CS foam was prepared by replacing glycerin with biodegradable natural polysaccharide CS.The results showed that the degradation performance of foam material was significantly improved,and the degradation rate of one week and five weeks were increased from 4.2%and 23.8%of PUF-control to 14.8%and 49.7%of PUF-CS foam,respectively.With the increase of CS content,the amount of tin catalyst could be reduced correspondingly,and the cellular toxicity of foam was significantly reduced while the foaming process performance was maintained.The cell survival rate could be increased from 39.37%to 84.96%.However,with the increase of CS,the water absorption capacity and flexibility of the foams deteriorated.3.PUF-QCS was prepared with QCS as chain extender,which not only solved the problem of poor physical properties of PUF-CS,but also endowed the material with antibacterial function.PUF-QCS had better physical properties than PUF-CS,and PUF-QCS4 with 0.6 g QCS addition was more ideal.Its apparent density was 0.133 g/cm~3,its water absorption was 19.44 g/g,and its wet and dry compressive strengths were 14.5 k Pa and 7.7 k Pa,respectively.The antibacterial experiments showed that PUF-QCS4 could kill97.35%S.aureus or 91.81%E.coli within six hours and its antibacterial effect lasted for at least seven days.The animal experiments showed that PUF-QCS4had a good hemostatic effect in nasal cavity packing.Compared with the commercially available PVA nasal packing sponge,the hemostatic time was shortened by nearly 50.0%,while the blood loss was reduced by 76.1%.Moreover,the antibacterial effect in nasal cavity was also significant.