Advanced materials Department, Jožef Stefan Institute, Ljubljana, Slovenia.
Jožef Stefan International Postgraduate School, Ljubljana, Slovenia.
Biomater Sci. 2022 Aug 24;10(17):4933-4948. doi: 10.1039/d2bm00644h.
Cell stimulation using piezoelectric polymers, which is known as piezostimulation, is an innovative approach for designing antimicrobial protection. As an antibiotic-free and inorganic nanoparticle-free approach, it uses physical stimuli to target bacterial cells in a non-specific manner, which may be of great importance, particularly in the context of avoiding resistant bacterial strains. In this study, we prepared fully organic piezoelectric biodegradable films composed of poly-L-lactide (PLLA) and demonstrated their antimicrobial effect on as a model of Gram-positive and as a model of Gram-negative bacteria. The PLLA films were either smooth and fabricated using simple melt- drawing or nanotextured, as self-standing nanotubes formed using the template-assisted method. The morphological differences between nanotextured and smooth films resulted in a larger surface area and better surface contact in nanotextured films, together with improved structural properties and better crystallinity, which were the main reasons for their better piezoelectric properties, and consequently stronger bactericidal effect. The comparison between the nanotextured surfaces with and without piezoelectric nature excluded the main role of morphology and directly confirmed piezoelectricity as the main reason for the observed antimicrobial affect. We also confirmed that piezo-stimulation using the antibacterial nanotextured film could damage the bacterial membrane as the main mechanism of action, while the contribution of pH changes and ROS generation was negligible. More importantly, the effect was selective toward the bacterial membrane and the same damage was not observed in human red blood cells, making the therapeutic use of these films possible.
利用压电聚合物进行细胞刺激，即压电刺激，是设计抗菌保护的一种创新方法。作为一种无抗生素和无机纳米颗粒的方法，它利用物理刺激以非特异性方式靶向细菌细胞，这可能非常重要，特别是在避免耐药菌的情况下。在这项研究中，我们制备了完全由聚 L-乳酸（PLLA）组成的有机压电可生物降解薄膜，并以革兰氏阳性菌 和革兰氏阴性菌 为模型，展示了它们对这些细菌的抗菌效果。PLLA 薄膜要么是光滑的，通过简单的熔融拉伸制备，要么是纳米结构的，通过模板辅助方法形成自支撑纳米管。纳米结构和光滑薄膜之间的形态差异导致纳米结构薄膜具有更大的表面积和更好的表面接触，以及改进的结构特性和更好的结晶度，这是它们具有更好的压电性能的主要原因，从而具有更强的杀菌效果。具有和不具有压电性质的纳米结构化表面之间的比较排除了形态的主要作用，并直接证实了压电性是观察到的抗菌作用的主要原因。我们还证实，使用抗菌纳米结构化薄膜进行的压电刺激可以破坏细菌膜，作为主要作用机制，而 pH 值变化和 ROS 生成的贡献可以忽略不计。更重要的是，这种效应是针对细菌膜的，在人红细胞中没有观察到相同的损伤，这使得这些薄膜的治疗应用成为可能。
