Department of Chemistry and College of Engineering and ‡New Materials Institute, University of Georgia , Athens, Georgia 30602, United States.
ACS Appl Mater Interfaces. 2017 Mar 1;9(8):7745-7751. doi: 10.1021/acsami.6b14940. Epub 2017 Feb 13.
Poly quaternary "-oniums" derived from polyethylenimine (PEI), poly(vinyl-N-alkylpyridinium), or chitosan belong to a class of cationic polymers that are efficient antimicrobial agents. When dissolved in solution, the positively charged polycations are able to displace the divalent cations of the cellular phospholipid bilayer and disrupt the ionic cross-links and structural integrity of the membrane. However, when immobilized to a surface where confinement limits diffusion, poly -oniums still show excellent antimicrobial activity, which implies a different biocidal mode of action. Recently, a proposed mechanism, named phospholipid sponge effect, suggested that surface-bound polycationic networks are capable of recruiting negatively charged phospholipids out of the bacterial cell membrane and sequestering them within the polymer matrix.1 However, there has been insufficient evidence to support this hypothesis. In this study, a surface-bound N,N-dodecyl methyl-co-N,N-methylbenzophenone methyl quaternary PEI (DMBQPEI) was prepared to verify the phospholipid sponge effect. By tuning the irradiation time, the cross-linking densities of surface-bound DMBQPEI films were mediated. The modulus of films was measured by PeakForce Quantitative Nanomechanical Mapping (QNM) to indicate the cross-linking density variation with increasing irradiation time. A negative correlation between the film cross-linking density and the absorption of a negatively charged phospholipid (DPhPG) was observed, but no such correlations were observed with a neutral phospholipid (DPhPC), which strongly supported the action of anionic phospholipid suction proposed in the lipid sponge effect. Moreover, the killing efficiency toward S. aureus and E. coli was inversely affected by the cross-linking density of the films, providing evidence for the phospholipid sponge effect. The relationship between killing efficiency and film cross-linking density is discussed.
聚季铵盐 "-onium" 衍生自聚乙烯亚胺 (PEI)、聚 (乙烯基-N-烷基吡啶𬭩) 或壳聚糖，属于一类阳离子聚合物，具有高效的抗菌性能。当溶解在溶液中时，带正电荷的聚阳离子能够取代细胞磷脂双层的二价阳离子，并破坏膜的离子交联和结构完整性。然而，当固定在限制扩散的表面上时，聚 -onium 仍然表现出出色的抗菌活性，这意味着存在不同的杀菌作用模式。最近，提出了一种名为磷脂海绵效应的机制，该机制表明，表面结合的聚阳离子网络能够从细菌细胞膜中招募带负电荷的磷脂，并将其隔离在聚合物基质内。1 然而，目前还没有足够的证据支持这一假设。在这项研究中，制备了表面结合的 N,N-十二烷基甲基-co-N,N-甲基二苯甲酮甲基季铵化聚乙烯亚胺 (DMBQPEI) 以验证磷脂海绵效应。通过调整辐照时间，调节表面结合的 DMBQPEI 膜的交联密度。通过 PeakForce 定量纳米力学映射 (QNM) 测量薄膜的模量，以指示随辐照时间增加的交联密度变化。观察到薄膜交联密度与带负电荷的磷脂 (DPhPG) 吸收之间存在负相关，但与中性磷脂 (DPhPC) 之间没有这种相关性，这强烈支持了在脂质海绵效应中提出的阴离子磷脂抽吸作用。此外，金黄色葡萄球菌和大肠杆菌的杀伤效率与薄膜的交联密度呈负相关，为磷脂海绵效应提供了证据。讨论了杀伤效率与薄膜交联密度之间的关系。
