title: Synergistic effect of static magnetic field and HA-Fe3O4 magnetic composites on viability of S. aureus and E. coli bacteria.
abstract: In addressing the issue of prosthetic infection, this work demonstrated the synergistic effect of the application of static magnetic field (SMF) and ferrimagnetic substrate properties on the bactericidal property in vitro. This aspect was studied using hydroxyapatite (HA)-xFe3 O4 (x=10, 20, and 40 wt.%) substrates, which have different saturation magnetization properties. During bacteria culture experiments, 100 mT SMF was applied to growth medium (with HA-xFe3 O4 substrate) in vitro for 30, 120, and 240 min. A combination of MTT assay, membrane rupture assays, live/dead assay, and fluorescence microscopic analysis showed that the bactericidal effect of SMF increases with the exposure duration as well as increasing Fe3 O4 content in biomaterial substrates. Importantly, the synergistic bactericidal effect was found to be independent of bacterial cell type, as similar qualitative trend is measured with both gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus) strains. The reduction in E. coli viability was 83% higher on HA-40 Wt % Fe3 O4 composite after 4 h exposure to SMF as compared to nonexposed control. Interestingly, any statistically significant difference in ROS was not observed in bacterial growth medium after magnetic field exposure, indicating the absence of ROS enhancement due to magnetic field. Overall, this study illustrates significant role being played by magnetic substrate compositions towards bactericidal property than by magnetic field exposure alone.
authors.affiliation: Department of Materials Science and Engineering, Laboratory for Biomaterials, Indian Institute of Technology, Kanpur, 208016, Uttar Pradesh, India.
authors.forename: Indu
authors.initials: I
authors.lastname: Bajpai
authors.forename: Kantesh
authors.initials: K
authors.lastname: Balani
authors.forename: Bikramjit
authors.initials: B
authors.lastname: Basu
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D001672:Biocompatible Materials / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000528:radiation effects; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000528:radiation effects; D004396:Coloring Agents; D017886:Durapatite / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000528:radiation effects*; D005290:Ferric Compounds / Q000494:pharmacology*; D060526:Magnetic Fields; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D017382:Reactive Oxygen Species / Q000528:radiation effects; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development / Q000528:radiation effects*; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D000900:Anti-Bacterial Agents; D001672:Biocompatible Materials; D004396:Coloring Agents; D005290:Ferric Compounds; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; C000499:ferric oxide; D017886:Durapatite; C022616:thiazolyl blue
keywords: bactericidal effect; magnetic biocomposites; static magnetic field