Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, West Bengal, India.
Colloids Surf B Biointerfaces. 2020 Apr;188:110822. doi: 10.1016/j.colsurfb.2020.110822. Epub 2020 Jan 22.
Investigating the role of molecular size and interfacial potential dependent antimicrobial propensity of nanoparticles (NPs) against bacteria is the important goal for secure usage of NPs to any living systems. In this study, crude silk sericin protein of Antheraea mylitta cocoon was fractionated into three different molecular size-ranges fractions such as fraction-1 (50-300 kDa), fraction-2 (30-50 kDa) and fraction-3 (10-30 kDa), and used to prepare crude sericin nanoparticles (CRSNPs), as well as fraction specific negative surface potential nanoparticles : n-SNP1, n-SNP2 and n-SNP3, respectively. SNPs were coated with poly-l-lysine to make the surface potential positive (p-SNPs) and confirmed through UV-vis spectroscopy, FTIR, zeta sizer and zeta potential measurement. The shape and sizes of all SNPs were determined by electron microscopy and found spherical in shape having diameter ranging from 110-165 nm (CRSNPs), 66-85 nm (SNP1), 33-49 nm (SNP2) and 14-24 nm (SNP3) for n-SNPs and p-SNPs, respectively. Evaluation of antibacterial activity using different concentrations (50, 100, 200 μg/mL) of all these SNPs showed significantly more activity of p-SNPs than n-SNPs against Staphylococcus aureus and Escherichia coli. Among these, SNP2 showed the strongest antibacterial activity followed by SNP3, SNP1 and CRSNPs. Relatively higher amounts of reactive oxygen species (ROS) generation were observed after treatment of bacteria with p-SNP2 (50 μg/mL) which is non-toxic to human cells. FE-SEM analysis showed more disruption of bacterial cell membrane after treatment with p-SNPs than n-SNPs. All these data suggested that molecular size and interfacial potential of SNPs enhance ROS generation to exert their antibacterial activity.
研究纳米粒子（NPs）的分子大小和界面电位依赖性抗菌倾向在将 NPs 安全应用于任何生命系统方面是一个重要目标。在这项研究中，将 Antheraea mylitta 茧的粗丝素蛋白分成三个不同的分子大小范围的级分，如级分 1（50-300 kDa）、级分 2（30-50 kDa）和级分 3（10-30 kDa），并用于制备粗丝素纳米粒子（CRSNPs），以及具有特定负表面电位的级分特异性纳米粒子：n-SNP1、n-SNP2 和 n-SNP3。通过紫外可见光谱、傅里叶变换红外光谱、Zeta 粒径仪和 Zeta 电位测量，用聚-L-赖氨酸对 SNPs 进行涂层，使表面电位呈正（p-SNPs），并通过这些方法进行了确认。通过电子显微镜确定了所有 SNPs 的形状和大小，发现它们均为球形，直径分别为 110-165nm（CRSNPs）、66-85nm（SNP1）、33-49nm（SNP2）和 14-24nm（SNP3），对于 n-SNPs 和 p-SNPs 分别为 110-165nm（CRSNPs）、66-85nm（SNP1）、33-49nm（SNP2）和 14-24nm（SNP3）。使用不同浓度（50、100、200μg/mL）的所有这些 SNPs 评估抗菌活性表明，与 n-SNPs 相比，p-SNPs 对金黄色葡萄球菌和大肠杆菌具有更强的活性。其中，SNP2 的抗菌活性最强，其次是 SNP3、SNP1 和 CRSNPs。在用 p-SNP2（50μg/mL）处理细菌后观察到相对较高量的活性氧（ROS）生成，而 p-SNP2 对人细胞无毒。FE-SEM 分析表明，在用 p-SNPs 处理后，细菌细胞膜的破坏程度高于 n-SNPs。所有这些数据表明，NPs 的分子大小和界面电位增强了 ROS 的产生，从而发挥其抗菌活性。
