Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Langmuir. 2010 Jun 1;26(11):8829-35. doi: 10.1021/la904589p.
Magnetite and metallic cobalt-based nanoparticles with sizes ranging from 10 to 300 nm and surface-functionalized with poly(hexamethylene biguanide) (PHMBG) are introduced as capable lipopolysaccharide (LPS)-sequestering agents. The nanoparticles efficiently bind to whole E. coli cells and can be used to separate the cells effectively from suspension using a magnet. A fluorescence dye displacement assay shows strong affinities of the nanoparticles for lipid A, the glycolipid component of LPS responsible for septic shock. The particle-lipid A affinity is of the same order of magnitude or higher than that of polymyxin B. The affinity of smaller (< 50 nm) magnetite particles modified with PHMBG to lipid A is several-fold higher than that of their larger counterparts (> 100 nm) due to their higher surface area to volume ratio. The nanoparticles possess high saturation capacity for double-stranded lambdaDNA from E. coli, with which particle-polyelectrolyte complexes are formed. The PHMBG-modified nanoparticles are potent bactericides, inhibiting E. coli viability and growth at concentrations at < or = 10 microg/mL.
粒径为 10 至 300nm 的磁性四氧化三铁和金属钴纳米颗粒经聚六亚甲基双胍（PHMBG）表面功能化后，可作为有效的脂多糖（LPS）螯合剂。这些纳米颗粒可有效地与大肠杆菌细胞结合，并可使用磁铁从悬浮液中有效分离细胞。荧光染料置换实验表明，纳米颗粒与脂多糖的糖脂成分脂磷壁酸具有很强的亲和力，脂磷壁酸是导致败血症休克的原因。纳米颗粒与脂磷壁酸的亲和力与多粘菌素 B 的亲和力相当或更高。由于其具有更高的表面积与体积比，经 PHMBG 修饰的粒径小于 50nm 的小磁铁颗粒对脂磷壁酸的亲和力要比粒径大于 100nm 的同类颗粒高几倍。这些纳米颗粒对来自大肠杆菌的双链 lambdaDNA 具有高饱和容量，并与颗粒-聚电解质复合物形成。经 PHMBG 修饰的纳米颗粒是有效的杀菌剂，在浓度为 <或= 10μg/mL 时可抑制大肠杆菌的活力和生长。
