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A microscopy method for scanning transmission electron microscopy imaging of the antibacterial activity of polymeric nanoparticles on a biofilm with an ionic liquid
Author(s) -
Takahashi Chisato,
Muto Shunsuke,
Yamamoto Hiromitsu
Publication year - 2017
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.33680
Subject(s) - transmission electron microscopy , scanning electron microscope , ionic bonding , microscopy , materials science , biofilm , nanoparticle , scanning confocal electron microscopy , nanotechnology , ionic liquid , polymer characterization , chemical engineering , scanning transmission electron microscopy , chemistry , optics , energy filtered transmission electron microscopy , bacteria , composite material , organic chemistry , ion , physics , biology , engineering , genetics , catalysis
In this study, we developed a scanning transmission electron microscopy (STEM) method for imaging the antibacterial activity of organic polymeric nanoparticles (NPs) toward biofilms formed by Staphylococcus epidermidis bacterial cells, for optimizing NPs to treat biofilm infections. The combination of sample preparation method using a hydrophilic ionic liquid (IL) and STEM observation using the cooling holder eliminates the need for specialized equipment and techniques for biological sample preparation. The annular dark‐field STEM results indicated that the two types of biodegradable poly‐(DL‐lactide‐co‐glycolide) (PLGA) NPs: PLGA modified with chitosan (CS), and clarithromycin (CAM)‐loaded + CS‐modified PLGA, prepared by emulsion solvent diffusion exhibited different antibacterial activities in nanoscale. To confirm damage to the sample during STEM observation, we observed the PLGA NPs and the biofilm treated with PLGA NPs by both the conventional method and the newly developed method. The optimized method allows microstructure of the biofilm treated with PLGA NPs to be maintained for 25 min at a current flow of 40 pA. The developed simple sample preparation method would be helpful to understand the interaction of drugs with target materials. In addition, this technique could contribute to the visualization of other deformable composite materials at the nanoscale level. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1432–1437, 2017.