Bacterial biofilms tolerate extreme levels of antibiotics. Treatment of biofilm infections therefore requires the development of new or modified antimicrobials that can penetrate biofilms and are effective against dormant persistent cells. One such new approach uses the biodegradable biopolymer chitosan and its derivatives as antimicrobials. In this study, we performed synthetic modification of chitosan to selectively introduce different cationic and hydrophobic moieties at varying ratios on chitosan. This improved its aqueous solubility and antimicrobial activity toward bacterial biofilms. Initial evaluation of the chitosan derivatives showed increased activity toward planktonic Staphylococcus aureus. The effect of the quaternary ammoniumyl chitosan derivatives against Staphylococcus aureus biofilms was more variable. The most effective derivatives contained hydrophobic groups, and their efficacy against biofilms depended on the ratio and length of the alkyl chains. Three-dimensional imaging of biofilms confirmed the accessibility and antimicrobial effect of chitosan derivatives with alkyl chains in the full depth of the biofilms.

中文翻译：

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季铵基壳聚糖衍生物消除金黄色葡萄球菌生物膜

细菌生物膜可耐受极端水平的抗生素。因此，生物膜感染的治疗需要开发能够穿透生物膜并有效对抗休眠的持久性细胞的新的或改良的抗菌剂。一种这样的新方法使用可生物降解的生物聚合物壳聚糖及其衍生物作为抗微生物剂。在这项研究中，我们进行了壳聚糖的合成修饰，以选择性地在壳聚糖上以不同比例引入不同的阳离子和疏水部分。这改善了其对细菌生物膜的水溶性和抗微生物活性。壳聚糖衍生物的初步评估显示对浮游金黄色葡萄球菌的活性增加。季铵基壳聚糖衍生物对金黄色葡萄球菌的作用生物膜的变化更大。最有效的衍生物包含疏水基团，其对生物膜的功效取决于烷基链的比例和长度。生物膜的三维成像证实了在生物膜的整个深度中具有烷基链的壳聚糖衍生物的可及性和抗菌作用。