动态多孔海绵结构多层膜负载溶菌酶用于抗菌涂层的研究

Dynamic Spongy Microporous Films to Load Lysozyme for Antibacterial Coating

以聚丙烯酸(PAA)和聚乙烯亚胺(PEI)为构筑单元,运用层层自组装技术制备了聚电解质多层膜.该多层膜具有独特的动态特点——经酸处理后膜内部形成海绵状通孔结构,该海绵结构在饱和水蒸气的处理下,多孔结构能够闭合,重新回到致密的膜结构.借助该种动态多层膜平台,能够简单有效地通过毛细作用力将溶菌酶负载并固定于多层膜中,为制备基于抗菌蛋白的抗菌涂层提供了新的方法.扫描电镜表征了多层膜动态变化过程,激光共聚焦显微镜表征了溶菌酶在膜内的分布情况,并测定了溶菌酶载入量及其释放动力学.进一步的抗菌测试表明该种抗菌涂层在溶菌酶和PEI的共同作用下可以有效地抑制金黄色葡萄球菌.将多层膜同时负载溶菌酶和乳铁蛋白,提升了涂层对大肠杆菌的杀菌效果.

Polyelectrolyte multilayer films were fabricated by layer-by-layer deposition of polyacrylic acid （PAA） and polyethyleneimine （PE1）. The （PAA/PEI） films showed unique dynamic properties owning to the high mobility of the polymer molecules： the spongy microporous structure was formed through an acid treatment for 60 rain; and the porous structure disappeared under a 100% relative humidity treatment, back to a solid film. Based on this （PAA/PEI） platform, lysozyme was easily loaded into the film via a wicking action in 5 s, and then easily immobilized into the film after 8 h conservation in humid atmosphere, providing therefore a novel approach to prepare antibacterial coating without any specific requirement for the characteristic of the agents. Scanning electron microscope was employed to show the dynamic transformation of film structures, from the original film with 9.5 nm of thickness to spongy sporous film with 68 nm of thickness and back to the solid film of 12 nm after the conservation process. Confocal scanning laser microscope image showed an even distribution of lysozyme in the film with lysozyme labelled by FITC. Loading quantity and the release dynamics of lysozyme were tested utilizing ultraviolet-visible spectrophotometer. Further, gram positive bacteria S. aureus and gram negative bacteria E. coli were tested in the antibacterial assay. The result illustrated that the coating was able to kill S. aureus efficiently, and the antibacterial activity of lysozyme was not affected by such loading and releasing process. To further enhance the bactericidal effect of the coating against gram negative bacteria, lysozyme and lactoferrin, which have synergistic killing effect on gram negative bacteria, were immobilized into the film at the same time and performed a distinct higher antibacterial efficiency against E. coli in comparison with the （PEI/PAA）~5-1ysozyme coating, revealing the attractive potential of this film as antibacterial coatings for medical devices to prevent the hospital-associated infections.