Wang Shiwei, Hou Yi, Zhang Shurong, Li Jing, Chen Qian, Yu Mingan, Li Wei
Department of Medicinal Chemistry, School of Pharmacy, Chongqing Medical University, Chongqing 400016, P. R. China.
J Mater Chem B. 2018 Aug 14;6(30):4972-4984. doi: 10.1039/c8tb01018h. Epub 2018 Jul 18.
The environmental risk from antibiotics is an issue of increasing concern. So, carboxymethyl β-cyclodextrin-functionalized montmorillonite nanosheets were for the first time successfully synthesized through a cheap, environmentally friendly and scalable approach and confirmed by FTIR, XRD and TGA. FE-SEM investigation showed that the resulting functional material could be further self-assembled into dense supramolecular organoclay networks (D-networks). The antibacterial properties of the D-networks loaded with natural berberine hydrochloride (BBH) were investigated toward E. coli and S. aureus by using colony growth on agar plates, bacterial growth curves based on optical densities, and confocal and fluorescence microscopy. Our studies demonstrated that the BBH loaded D-network antibacterial activity was concentration dependent and significantly exceeded that of free BBH. FE-SEM observation confirmed that E. coli and S. aureus can directly contact the D-networks and confocal and fluorescence microscopy showed that free BBH was only very poorly internalized, while the BBH released from the BBH-loaded D-network could be internalized efficiently into bacterial cells, resulting in an increment of the intracellular BBH level compared with the free BBH group. Time-dependent antibacterial activity was observed and it was found that the BBH-loaded D-network dispersion at the BBH dosage of 600 μg mL almost completely suppressed the growth of E. coli, leading to a viability loss of up to 98.45 ± 1.22%, while the BBH-loaded D-network dispersion at the BBH concentration of 250 μg mL exhibited a growth inhibition of 97.81 ± 0.83% toward S. aureus over three days. Our results suggest that supramolecular organoclay networks, in the future, may function as promising antibacterial drug carrier systems to promote BBH delivery in E. coli and S. aureus, which can reduce the environmental risk of antibiotics.
抗生素带来的环境风险是一个日益受到关注的问题。因此，首次通过一种廉价、环保且可扩展的方法成功合成了羧甲基β-环糊精功能化蒙脱石纳米片，并通过傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）和热重分析（TGA）进行了表征。场发射扫描电子显微镜（FE-SEM）研究表明，所得功能材料可进一步自组装成致密的超分子有机粘土网络（D-网络）。通过琼脂平板上的菌落生长、基于光密度的细菌生长曲线以及共聚焦和荧光显微镜，研究了负载天然盐酸小檗碱（BBH）的D-网络对大肠杆菌和金黄色葡萄球菌的抗菌性能。我们的研究表明，负载BBH的D-网络抗菌活性具有浓度依赖性，且显著超过游离BBH。FE-SEM观察证实大肠杆菌和金黄色葡萄球菌可直接接触D-网络，共聚焦和荧光显微镜显示游离BBH的内化程度很低，而从负载BBH的D-网络释放的BBH可有效内化到细菌细胞中，与游离BBH组相比，导致细胞内BBH水平升高。观察到了时间依赖性抗菌活性，发现当BBH剂量为600 μg/mL时，负载BBH的D-网络分散液几乎完全抑制了大肠杆菌的生长，导致存活率损失高达98.45±1.22%，而当BBH浓度为250 μg/mL时，负载BBH的D-网络分散液在三天内对金黄色葡萄球菌的生长抑制率为97.81±0.83%。我们的结果表明，超分子有机粘土网络未来可能成为有前景的抗菌药物载体系统，以促进BBH在大肠杆菌和金黄色葡萄球菌中的递送，从而降低抗生素的环境风险。
