【作者】 徐雄立；

【导师】 周美华；

【作者基本信息】 东华大学 ， 环境工程， 2009， 博士

【摘要】 医用敷料是一种一次性使用的医疗护理用品,使用后的敷料是一种具有高度危险性的医疗废物,容易造成交叉感染和环境污染,需要进行集中处理。我国每年产生大量的敷料废物,给处理工作和环境保护造成巨大的压力,如何对这种危险医疗废物进行减量化已引起人们的高度重视。因此,研究设计高性能的新型敷料,提高治疗效果,从源头上减少敷料用量,达到节约资源,减少废物排放量,成为一项紧迫的任务。本文在利用静电纺丝技术制备抗菌型医用敷料方面进行了尝试,为开拓纳米纤维应用及新的敷料制备方法提供有益的参考。本文从生态环境材料的角度出发,选用可生物降解的环保型天然高分子材料——明胶和壳聚糖作为主要原料,采用静电纺丝的方法制备了含有纳米银的明胶基纳米纤维凝胶,用来制备抗菌型水凝胶敷料,以提高治愈效果,减少换药次数,达到减少危险废物产生量的目的。文中系统地研究了静电纺丝工艺条件对纳米纤维及纳米银形态的影响,找到了合适的纺丝条件,并对这种凝胶纤维的交联和溶胀进行了探讨,同时对这两种纤维膜中银离子的释放,以及对金黄色葡萄球菌和绿脓杆菌的抑菌性能进行了初步的研究,取得了以下主要研究结果:采用静电纺丝技术制备了一类新型含纳米银颗粒的明胶纳米纤维,纤维平均直径91～145 nm,纤维表面银纳米颗粒平均直径9～20 nm。研究了明胶质量分数和硝酸银加入量对溶液可纺性的影响,并研究了纺丝工艺参数如纺丝电压、接收距离对纺丝性能的影响,发现在可纺性方面,纺丝体系中硝酸银的加入量存在一个极限值,并结合纺丝理论进行了分析,认为硝酸银加入量达到8%时,电导率增长幅度减小引起射流的电势发生变化,纺丝不稳定性提前发生。经过静电纺丝和紫外光照后,在明胶纳米纤维表面均匀地分布着类似球形的银纳米颗粒,在紫外光照3 h后纳米银颗粒平均直径不变,根据Scherrer方程估算的纳米银颗粒平均直径与采用透射电镜观测结果相吻合。对纳米银形成机理进行了探讨,提出了纤维中银离子的光还原反应式。通过在明胶/硝酸银纺丝体系中添加壳聚糖,制备了新型的含纳米银颗料的明胶/壳聚糖纳米纤维,纤维平均直径101～167nm,纤维表面银纳米颗粒的平均直径8～17 nm。壳聚糖的加入增大了纳米纤维的平均直径,并提高了明胶体系中硝酸银加入量的极限值,使极限值达到了14%,分析认为这与壳聚糖的加入改变了纺丝溶液的电导率增长幅度有关。研究发现,加入壳聚糖后用紫外光照还原时4 h后纳米银颗粒的平均直径不变,添加相同量的硝酸银时,与明胶/银纳米纤维相比,在明胶/壳聚糖/银纳米纤维表面所形成的纳米银颗粒平均直径减小,但数超增多。采用戊二醛蒸汽对两种含纳米银的纳米纤维膜进行了交联,交联后的纳米纤维膜是一种凝胶材料,抗张强度达到12.06 MPa,弹性模量达到437.8 MPa。纳米纤维凝胶在磷酸盐缓冲溶液中发生溶胀形成水凝胶,并在5～10 min接近溶胀平衡,溶胀度达到5 g/g。研究了两种纳米纤维水凝胶的溶胀动力学。交联剂的浓度和交联时间对纤维膜的溶胀性具有显著的影响。同时还发现,在溶胀24 h后纤维膜仍可以保持纤维的基本形态及孔隙结构。研究了两种含纳米银的纳米纤维膜在磷酸盐溶液中银离子的释放性能,结果表明经紫外光照射后的含银纳米纤维膜可以达到缓慢释放出银离子的效果。两种含纳米银的纳米纤维对金黄色葡萄球菌和绿脓杆菌具有较好的抑菌性能,发现仅添加1%硝酸银制得的纤维膜对两种病原菌均具有99%以上的抑菌率。纤维膜不仅具有较好的吸水性,可吸收大量的伤口渗出液并形成有利于创面愈合的湿润环境,同时可将银离子缓慢释放出来,用在创面上起到持续消炎抑菌的效果,可加快伤口愈合,因此这两种纳米纤维膜是较为理想的医用敷料材料。分析了新型医用敷料对环境的影响,通过对产品生命周期内对环境的影响和经济性分析认为,与目前我国大量使用的传统纱布敷料相比,制得的新型敷料具有更好的环境性能,可以从源头上减少了敷料的用量,并节约资源和能源,减轻我国危险医疗废物处理的压力和对环境的污染,同时经济上也具有一定的优势,因此无论在伤口护理方面还是保护环境方面都具有较好的应用价值。更多还原

【Abstract】 Wound dressing is a kind of disposable medical articles which becomes hazardous medical waste after usage.The wound dressing waste must be concentrated and treated.The wound dressing wastes which have not been treated effectively can cause intersectional infection and environmental pollution.The huge amount of hazardous wound dressing waste leads to a burden to the treatment departments and environmental protection in China.Now the treatment ratio of wound dressing waste is low and the incinerating disposal method always leads to the secondary pollution.Many countries have focused on the quantity-reducing method of hazardous medical waste.So it is urgent to develop new high-efficient wound dressing products to decrease the using quantity and discharged waste quantity by improving healing effect.In this article,we attempted to prepare new antibacterial wound dressing product by electrospinning,which can provide reference for the application of nanofibers and developing new type of wound dressing.By focusing on eco-environmental material,the degradable natural polymer gelatin and chitosan were chosen as the main raw material to prepare nanofiber hydrogel containing silver nanoparticles by electrospiinning.The as-spun nanofibers can be used to prepare antimicrobial wound dressing product to improve healing effects and reduce dressing-change times.So the new type of wound dressing can reduce the amount of hazardous waste.The influence of electrospinning process conditions to the morphology of the nanofibers and silver nanoparticles was investigated and the proper electrospining conditions were obtained.The crosslinking and swelling of nanofiber hydrogel were studied.The nanofibers can release silver ions and show strong antibacterial activity to Staphylococcus aureas and Pseudomonas aeruginosa.The main results obtained are as following.A new kind of gelatin nanofibers containing silver was prepared by electrospinning technique. The average diameter of gelatin/Ag nanofibers is 91～145 nm,and the average size of silver nanoparticles is 9～20 nm.The influence of gelatin concentration and the amount of AgNO₃ added to the spinnability of solution and the influence of electrospinning conditions such as electrospinning voltage and collection distance to the morphology of nanofibers was investigated. It was found that there is a critical amount value of added AgNO₃ during electrospinning.The behaviors were investigated in details with electrospinning theory.When the content of AgNO₃ attained 8%,the conductivity increasing ratio decreased which caused the change of electrical potential energy of spinning jet.So the jet instability occurs earlier.The morphology of nanofibers and silver nanoparticles was studied also.It was found that silver nanoparticles present quasi-sphere shaped and distributed homogenously on the surface of nanofibers after ultra-violet irradiation.The average diameter of silver nanoparticles did not change after irradiated for three hours.The average diameter values of silver nanoparticles estimated by Scherrer equation are similar to the results measured with transmission electron microscopy.The formation mechanism of silver nanoparticles was discussed and the photo-reduction reaction equation of silver ions was proposed.The new type of gelatin/chtosan nanofibers containing silver nanolparticels was prepared by adding chitosan into gelatin-AgNO₃ spinning solution.The average diameter of gelatin/chitosan/Ag nanofibers is 101～167 nm and the average size of silver nanoparticles is 8～17 nm.The average diameter of nanofibers and the critical amount value of AgNO₃ increased with adding chitosan into gelatin/AgNO₃ solution.The phenomenon was related with the increasing ratio of conductivity of spinning solution caused by adding chitosan.It is found that the average diameter of silver nanoparticles did not change after irradiated for four hours.By fixing the amount of AgNO₃ added,the average diameter of silver nanoparticles decrease and the quantity increase,compared with gelatin/Ag nanofibers.The nanofibers were cosslinked with saturated glutaraldehyde vapor to prepare nanofiber hydrogels.The crosslinked nanofibrous film’s tensile strength and Young’s modulus can attain 12.06 MPa and 437.8 MPa,respectively.The nanofiber can swell in phosphate buffer solution to form hydrogel and the swelling equillium can be attained during 10～15 min.The swelling degree can attain 5 g/g.The dissolution ratio and welling kinetics of nanofibrous films was studied.The influence of crosslinking time to the mechanical strength and swelling properties of nanofibber was distinct.The scanning electron microscopy photographs of nanofibers showed that the nanofibers can keep fibrous shape after immerged in phosphate buffer solution for 24 h.The release of silver ions of gelatin/Ag nanofiber and gelatin/chitosan/Ag was investigated.It was shown that controlled release of silver ions can be attained.The antibacterial tests against Staphylococcus aureas and Pseudomonas aeruginosa showed the inhibition ratios were more than 99%when 1.0 wt%AgNO₃ was added into spinning solution during electrospinning process.The nanofiber wound dressing can not only absorb a large amount of wound liquid to create a moist environment but also release silver ions to provide sustained antibacterial activity to avoid infection.The new wound dressing can improve wound healing effect remarkably.So the two kinds of nanofibrous films can be used as ideal wound dressing materials.The environmental impact of the new type of wound dressing made from gelatin-based nanofiber hydrogel was analyzed.Through environmental impact and economical analysis, compared with the traditional gauze wound dressing,the new wound dressing can reduce the usage amount of wound dressing and decrease consuming of resource and energy,and alleviate the treatment burden of hazardous medical waste and pollution to the environment.So this type of product is economical and highly valuable in both wound care and environmental protection.更多还原