Abstract: Hollow polyurethane (PU) nanofiber was prepared by co-axial electrospinning with glycerol containing certain content of water and PU dissolved in organic solvent as internal and external phase electrospinning solutions, respectively. The effects of the solution composition and flow rate, and diameter of co-axial spinneret on the morphology, mechanical strength and surface wetability of the nanofiber were investigated. The results showed that uniform hollow PU nanofiber was successfully fabricated by co-axial electrospinning glycerol containing 5%(j) water and N,N-dimethylacetamide solution of 30%(w) PU as internal and external phase electrospinning solution under the conditions of the solution flow rates of 0.07 and 0.5 mL/h, voltage 17 kV, distance between spinneret and collector 25 cm, temperature 25℃, and humility 10%. Hollow PU nanofiber prepared under above conditions had membrane tensile strength of 3.9 MPa and elongation at break of 332.8%, and contact angle with water of 100.2o. By dissolving definite amount of horseradish peroxidase (HRP) in the internal phase electrospinning solution, the enzyme was in-situ encapsulated inside the hollow channel of PU nanofiber. The kinetic biocatalytic activity of encapsulated HRP showed that an activity recovery rate of 80% was obtained, and similar Michaelis-Menten constant, Km, was observed for the free and encapsulated HRP. Thermal stability of HRP showed that the half-life of HRP at 60℃ was prolonged about 17 times after encapsulation.

Key words: co-axial electrospinning, polyurethane, hollow nanofiber, mechanical strength, enzyme immobilization

摘要： 利用同轴共纺技术，以含水甘油和溶解于有机溶剂中的聚氨酯(PU)溶液作为内、外相电纺液，制备中空PU纳米纤维，研究了电纺液组成及流速、同轴喷丝头尺寸对其结构、机械强度及表面亲疏水性的影响. 结果表明，以含水量5%(j)的甘油溶液为内相电纺液、以溶解于N,N-二甲基乙酰胺的30%(w) PU溶液为外相电纺液、内外相电纺液流速分别为0.07和0.5 mL/h、电压17 kV、针头到接收板距离为25 cm、温度25℃、湿度10%条件下，可制备出结构均一的中空纳米纤维，纤维膜的拉伸强度为3.9 MPa，最大拉伸率为332.8%，与水表面接触角为100.2o. 将辣根过氧化物酶(HRP)溶解于内相电纺液中，实现了酶在中空纳米纤维腔室内的原位包埋. 在上述电纺条件下，固定化HRP的活性收率为游离酶的80%，米氏常数Km几乎与游离酶相同，固定化酶在60℃下的半衰期比游离酶提高17倍.

关键词: 同轴共纺, 聚氨酯, 中空纳米纤维, 机械性能, 固定化酶