柔性壳聚糖抗菌膜的制备及性能研究

Preparation and Properties of Antibacterial Chitosan-based Composite Films with Good Flexibility

目的获得具有优异柔性与抗菌活性的壳聚糖复合膜。方法以明胶为增强聚合物,甘油为增塑剂,采用流延成型法构筑柔性壳聚糖薄膜,并通过浸泡硝酸铜/氢氧化钠溶液原位负载纳米氧化铜,以提高薄膜的抗菌性。研究壳聚糖同明胶的质量比及甘油添加量对复合膜力学性能的影响,考察硝酸铜浓度对复合膜水蒸气透过率、透光率、抗菌性的影响。通过红外光谱(FT-IR)和X-射线衍射(XRD)对薄膜结构进行表征。结果当壳聚糖与明胶的质量比为5∶5,甘油质量分数为20%时,复合膜拉伸强度为(3.23±0.31)MPa,断裂伸长率为(159.88±4.14)%。增加硝酸铜浓度,壳聚糖/明胶/氧化铜复合膜的水蒸气透过率先降低后增加,透光率逐渐降低,对金黄色葡萄球菌与大肠杆菌的抗菌活性逐渐增强。当硝酸铜浓度为0.05 mol/L时,复合膜的最佳水蒸气透过率为(30.60±4.02)g·mm/(m^2·s·kPa),最佳透光率为(72.61±8.13)%;当硝酸铜浓度为0.25 mol/L时,复合膜对大肠杆菌的最大抑菌圈直径为(27.0±3.0)mm;当硝酸铜浓度为0.30mol/L时,复合膜对金黄色葡萄球菌的最大抑菌圈直径为(26.1±3.1)mm。结论制备得到的壳聚糖/明胶复合膜具有优异的柔性和抗菌活性,在食品包装保鲜领域具有潜在的应用前景。

The work aims to obtain chitosan-based composite films with good flexibility and antibacterial ability.Chitosan was firstly reinforced by gelatin and then was plasticized by glycerol to prepare chitosan-based films with good flexibility by means of tape casting.After that,the films were soaked in copper nitrate/sodium hydroxide solution to improve their antibacterial property by in-situ loading nano-CuO particles.The effects of the mass ratio of chitosan to gelatin and the dosage of glycerol on the mechanical properties of the composite films were investigated.Also,the effects of the concentration of copper nitrate on the water vapor permeability(WVP),transmittance and antibacterial property of the composite films were studied.FT-IR and XRD were used to characterize the structure of films.The results indicated that,with the mass ratio of chitosan to gelatin of 5∶5 and the mass fraction of glycerin of 20%,the tensile strength and elongation at break of the composite film were(3.23±0.31)MPa and(159.88±4.14)%,respectively.The concentration of copper nitrate increased,the WVP of chitosan/gelatin/copper nitrate films decreased and then increased,while the transmittance gradually decreased.Moreover,the antibacterial activity of composite films against staphylococcus aureus and escherichia coli was gradually enhanced.With the concentration of copper nitrate of 0.05 mol/L,the optimum WVP and transmittance values of composite films were(30.60±4.02)g·mm/(m^2·s·kPa)and(72.61±8.13)%,respectively.When the concentration of copper nitrate was 0.25 mol/L,the film showed good antibacterial ability with the diameter of the inhibition zone for escherichia coli of(27.0±3.0)mm.With the concentration of copper nitrate of 0.30 mol/L,the maximum inhibition zone diameter of the film for the staphylococcus aureus was(26.1±3.1)mm.The chitosan/gelatin films obtained herein have good flexibility and antibacterial property,broadening its potential application in the field of food packaging preservation.