Abstract：
As we step into the post-antibiotic era, the accelerated emergence of antibiotic-resistant pathogenic bacteria poses an increasingly serious threat to public health. The formation of antibiotic-resistant biofilms further challenges currently available drugs and treatment options, calling for novel strategies for effective ablation of such biofilm with minimal concern on safety and development of resistance. Herein, we report a novel type of photodynamic nanoagent, composed of chlorin e6 (Ce6)-loaded water-soluble chitosan-coated iron oxide nanoparticles (named Ce6@WCS-IONP), for drug-resistant bacteria killing and biofilm eradication. The fabricated Ce6@WCS-IONP has negligible toxicity to mammalian cells and exhibited equivalent singlet oxygen generation capacity to free Ce6; however, its association with methicillin-resistant Staphylococcus aureus (MRSA) was greatly enhanced, as evidenced by flow cytometry analysis and transmission electron microscope. In vitro studies verified that Ce6@WCS-IONP has superior photodynamic bactericidal effect against planktonic MRSA. Furthermore, with the aid of the cationic nature and small size, Ce6@WCS-IONP could effectively penetrate into MRSA biofilm, revealed by 3D fluorescence imaging. Both biomass analysis and viable bacteria counting demonstrated that Ce6@WCS-IONP showed potent biofilm ablation efficacy, averagely 7.1 log unit lower than that in free Ce6 group upon identical light irradiation. In addition, local treatment of MRSA-infected mice with Ce6@WCS-IONP plus light irradiation resulted in significant antibacterial and wound healing effect, accompanied by good biocompatibility in vivo. Collectively, photosensitizer-loaded cationic IONP with effective biofilm penetration and photodynamic eradication potential might be a promising nano platform in fighting against antibiotic-resistant microbial pathogen and biofilm.
摘要：
当我们进入后抗生素时代时，抗生素抗性致病菌的加速出现对公众健康构成了日益严重的威胁。抗生素抗性生物膜的形成进一步挑战了目前可用的药物和治疗方案。呼吁采取新的策略来有效地消融这种生物膜，而对安全性和耐药性的发展却一无所知。在这里，我们报道了一种新型的光动力纳米剂，由负载氯e6（Ce6）的水溶性壳聚糖包覆的氧化铁纳米颗粒（命名为Ce6@WCS-IONP）组成，用于杀灭耐药细菌和根除生物膜。制造的Ce6@WCS-IONP对哺乳动物细胞的毒性可忽略不计，并且表现出与游离Ce6相当的单线态氧生成能力；然而，它与耐甲氧西林金黄色葡萄球菌（MRSA）的相关性大大增强，流式细胞术分析和透射电子显微镜证明。体外研究证实Ce6@WCS-IONP对浮游MRSA具有优越的光动力杀菌作用。此外，借助阳离子性质和小尺寸，Ce6@WCS-IONP可以有效地穿透MRSA生物膜，通过3D荧光成像显示。生物量分析和活菌计数均表明Ce6@WCS-IONP显示出有效的生物膜消融功效，在相同的光照下，平均比游离Ce6组低7.1个对数单位。此外,用Ce6@WCS-IONP加光照射对MRSA感染的小鼠进行局部治疗，可产生显着的抗菌和伤口愈合效果，体内生物相容性良好。总的来说，具有有效生物膜渗透和光动力根除潜力的光敏剂负载的阳离子IONP可能是对抗抗生素抗性微生物病原体和生物膜的有前途的纳米平台。
