title: Potential effect of cationic liposomes on interactions with oral bacterial cells and biofilms.
abstract: BACKGROUND
  Although oral infectious diseases have been attributed to bacteria, drug treatments remain ineffective because bacteria and their products exist as biofilms. Cationic liposomes have been suggested to electrostatically interact with the negative charge on the bacterial surface, thereby improving the effects of conventional drug therapies. However, the electrostatic interaction between oral bacteria and cationic liposomes has not yet been examined in detail.
  
  
  OBJECTIVE
  The aim of the present study was to examine the behavior of cationic liposomes and Streptococcus mutans in planktonic cells and biofilms.
  
  
  METHODS
  Liposomes with or without cationic lipid were prepared using a reverse-phase evaporation method. The zeta potentials of conventional liposomes (without cationic lipid) and cationic liposomes were -13 and 8 mV, respectively, and both had a mean particle size of approximately 180 nm. We first assessed the interaction between liposomes and planktonic bacterial cells with a flow cytometer. We then used a surface plasmon resonance method to examine the binding of liposomes to biofilms. We confirmed the binding behavior of liposomes with biofilms using confocal laser scanning microscopy.
  
  
  RESULTS
  The interactions between cationic liposomes and S. mutans cells and biofilms were stronger than those of conventional liposomes. Microscopic observations revealed that many cationic liposomes interacted with the bacterial mass and penetrated the deep layers of biofilms.
  
  
  CONCLUSIONS
  In this study, we demonstrated that cationic liposomes had higher affinity not only to oral bacterial cells, but also biofilms than conventional liposomes. This electrostatic interaction may be useful as a potential drug delivery system to biofilms.
authors.affiliation: a Division of Biomaterials & Engineering , Department of Conservative Dentistry, Showa University School of Dentistry , Shinagawa-ku, Tokyo , Japan .|b Department of Periodontology , Showa University School of Dentistry , Ohta-ku, Tokyo , Japan .|c Japan Society for the Promotion of Science (JSPS) , Chiyoda-ku, Tokyo , Japan .
authors.forename: Marika
authors.initials: M
authors.lastname: Sugano
authors.affiliation: d Department of Oral Microbiology , Showa University School of Dentistry , Shinagawa-ku, Tokyo , Japan , and.
authors.forename: Hirobumi
authors.initials: H
authors.lastname: Morisaki
authors.affiliation: e Department of Drug Delivery and Molecular Biopharmaceutics , School of Pharmacy, Tokyo University of Pharmacy and Life Sciences , Hachioji , Tokyo , Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Negishi
authors.affiliation: e Department of Drug Delivery and Molecular Biopharmaceutics , School of Pharmacy, Tokyo University of Pharmacy and Life Sciences , Hachioji , Tokyo , Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Endo-Takahashi
authors.affiliation: d Department of Oral Microbiology , Showa University School of Dentistry , Shinagawa-ku, Tokyo , Japan , and.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kuwata
authors.affiliation: a Division of Biomaterials & Engineering , Department of Conservative Dentistry, Showa University School of Dentistry , Shinagawa-ku, Tokyo , Japan .
authors.forename: Takashi
authors.initials: T
authors.lastname: Miyazaki
authors.affiliation: b Department of Periodontology , Showa University School of Dentistry , Ohta-ku, Tokyo , Japan .
authors.forename: Matsuo
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D018441:Biofilms; D002412:Cations / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D013295:Streptococcus mutans / Q000166:cytology* / Q000378:metabolism*
chemical_list: D002412:Cations; D008081:Liposomes
keywords: Cationic liposomes; dental biofilms; electrostatic interaction; surface plasmon resonance method; zeta potential