Department of Pharmacy, Uppsala University, SE-75123 Uppsala, Sweden.
Department of Pharmacy, Uppsala University, SE-75123 Uppsala, Sweden.
J Colloid Interface Sci. 2018 Mar 1;513:141-150. doi: 10.1016/j.jcis.2017.11.014. Epub 2017 Nov 6.
Microgels are interesting as potential delivery systems for antimicrobial peptides. In order to elucidate membrane interactions of such systems, we here investigate effects of microgel charge density on antimicrobial peptide loading and release, as well as consequences of this for membrane interactions and antimicrobial effects, using ellipsometry, circular dichroism spectroscopy, nanoparticle tracking analysis, dynamic light scattering and z-potential measurements. Anionic poly(ethyl acrylate-co-methacrylic acid) microgels were found to incorporate considerable amounts of the cationic antimicrobial peptides LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) and DPK-060 (GKHKNKGKKNGKHNGWKWWW) and to protect incorporated peptides from degradation by infection-related proteases at high microgel charge density. As a result of their net negative z-potential also at high peptide loading, neither empty nor peptide-loaded microgels adsorb at supported bacteria-mimicking membranes. Instead, membrane disruption is mediated almost exclusively by peptide release. Mirroring this, antimicrobial effects against several clinically relevant bacteria (methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa) were found to be promoted by factors facilitating peptide release, such as decreasing peptide length and decreasing microgel charge density. Microgels were further demonstrated to display low toxicity towards erythrocytes. Taken together, the results demonstrate some interesting opportunities for the use of microgels as delivery systems for antimicrobial peptides, but also highlight several key factors which need to be controlled for their successful use.
微凝胶作为抗菌肽的潜在递药系统具有重要意义。为了阐明此类系统的膜相互作用，我们在这里研究了微凝胶的电荷密度对抗菌肽负载和释放的影响，以及这对抗菌肽与膜相互作用和抗菌效果的影响，采用了椭圆测量法、圆二色光谱法、纳米颗粒跟踪分析、动态光散射和 Zeta 电位测量。发现阴离子聚（丙烯酸乙酯-共-甲基丙烯酸）微凝胶可以大量负载阳离子抗菌肽 LL-37（LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES）和 DPK-060（GKHKNKGKKNGKHNGWKWWW），并在高微凝胶电荷密度下保护负载的肽免受感染相关蛋白酶的降解。由于其净负 Zeta 电位在高肽负载时也存在，空微凝胶和负载肽的微凝胶都不会吸附在模拟支持细菌的膜上。相反，膜破坏几乎完全是由肽释放介导的。与之类似，抗菌肽对几种临床相关细菌（耐甲氧西林金黄色葡萄球菌（MRSA）、大肠杆菌和铜绿假单胞菌）的抗菌效果被发现受到促进肽释放的因素的促进，如肽长度的缩短和微凝胶电荷密度的降低。进一步证明微凝胶对红细胞的毒性较低。综上所述，这些结果表明了微凝胶作为抗菌肽递药系统的一些有趣的应用机会，但也强调了成功应用时需要控制的几个关键因素。
