Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, School of Life Science, Jilin University, Changchun 130012, Jilin, People's Republic of China.
Scientific Research Center, China-Japan Union Hospital, Jilin University, Changchun 130033, Jilin, People's Republic of China.
Int J Nanomedicine. 2019 Oct 4;14:8047-8058. doi: 10.2147/IJN.S212750. eCollection 2019.
Treatment strategies to eliminate bacterial infections have long emphasized bacterial killing as a goal. However, bacteria secrete toxins that sustain chronic disease and dead cells release DNA that can promote the spread of antibiotic resistance even when viable cells are eradicated. Meanwhile, biofilms regulated by quorum-sensing system, protect bacteria and promote the development of antibiotic resistance. Thus, all of these factors underscore the need for novel antimicrobial therapeutic treatments as alternatives to traditional antibiotics. Here, a smart material was developed that incorporated gold nanorods and an adsorbed protease (protease-conjugated gold nanorods, PGs). When illuminated with near-infrared (NIR) light, PGs functioned to physically damage bacteria, prevent biofilm and exotoxin production, eliminate pre-existing biofilm and exotoxin, and inhibit bacterial quorum-sensing systems.
PGs were incubated with suspensions of Gram-negative () and Gram-positive () bacteria followed by exposure to 808-nm NIR laser irradiation. Bacterial viability was determined using a colony-forming unit assay followed by an exploration of cell-damage mechanisms using transmission electron microscopy, scanning electron microscopy, agarose gel electrophoresis, and SDS-PAGE. Quantification of biofilm mass was performed using crystal violet staining. A commercial enterotoxin ELISA kit was used to test inhibitory and degradative effects of PGs on secreted exotoxin.
Use of the remote-controlled antibacterial system reduced surviving bacterial populations to 3.2% and 2.1% of untreated control numbers for and , respectively, and inhibited biofilm formation and exotoxin secretion even in the absence of NIR radiation. However, enhanced degradation of existing biofilm and exotoxin was observed when PGs were used with NIR laser irradiation.
This promising new strategy achieved both the reduction of viable microorganisms and elimination of biofilm and exotoxin. Thus, this strategy addresses the long-ignored issue of persistence of bacterial residues that perpetuate chronic illness in patients even after viable bacteria have been eradicated.
长期以来，消除细菌感染的治疗策略一直强调以杀菌为目标。然而，细菌会分泌毒素来维持慢性疾病，而死细胞释放的 DNA 即使在消灭了有活力的细胞后，也可以促进抗生素耐药性的传播。同时，由群体感应系统调节的生物膜可以保护细菌并促进抗生素耐药性的发展。因此，所有这些因素都强调需要新型的抗菌治疗方法来替代传统的抗生素。在这里，开发了一种智能材料，它结合了金纳米棒和吸附的蛋白酶（与蛋白酶结合的金纳米棒，PGs）。当用近红外（NIR）光照射时，PGs 可以物理损伤细菌，防止生物膜和外毒素的产生，消除现有的生物膜和外毒素，并抑制细菌群体感应系统。
将 PGs 与革兰氏阴性菌（）和革兰氏阳性菌（）的悬浮液孵育，然后用 808nm 的 NIR 激光照射。通过平板计数法测定细菌活力，然后通过透射电子显微镜、扫描电子显微镜、琼脂糖凝胶电泳和 SDS-PAGE 探索细胞损伤机制。使用结晶紫染色法定量生物膜质量。使用商业肠毒素 ELISA 试剂盒测试 PGs 对分泌的外毒素的抑制和降解作用。
使用遥控抗菌系统可将未处理对照组的存活细菌数量减少到 和 的 3.2%和 2.1%，即使没有 NIR 辐射，也能抑制生物膜形成和外毒素分泌。然而，当使用 NIR 激光照射时，观察到现有的生物膜和外毒素的降解增强。
这种有前景的新策略实现了减少活微生物和消除生物膜和外毒素的双重目标。因此，该策略解决了长期以来被忽视的问题，即即使有活力的细菌已经被消灭，细菌残留也会持续存在，从而使患者的慢性疾病持续存在。
