title: Photodynamic inactivation of chlorin e6-loaded CTAB-liposomes against Candida albicans.
abstract: OBJECTIVE
  Antimicrobial photodynamic inactivation (PDI) is a promising therapeutic modality for the treatment of local infections. To increase the efficacy of PDI, chlorine e6 (Ce6) was encapsulated in cationic CTAB-liposomes composed of various ratios of dimyristoyl-sn-glycero-phosphatidylcholine (DMPC) and the cationic surfactant, cetyltrimethyl ammonium bromide (CTAB). The PDI efficacy of the liposomal-Ce6 was assessed in vitro against susceptible and drug-resistant clinical isolates of Candida albicans (C. albicans) as well as in infected burn wounds.
  
  
  METHODS
  Ce6 was encapsulated in CTAB-liposomes by the film hydration method. Particle size distribution and zeta potential of the cationic liposomes were measured using a Zetasizer Nano-ZS. UV-visible spectra were used to measure lipid/Ce6 (L/C) ratio and drug entrapment efficiency while differential scanning calorimetry (DSC) was used to study the thermotropic behavior of DMPC liposomes upon CTAB addition. In vivo PDI efficacy was carried out in an infected burn wound using a rat model.
  
  
  RESULTS
  The increase in zeta potential and a shift in the phase transition temperature (Tm ) upon CTAB addition confirmed its entrapment within the lipid bilayers of the liposome. Meanwhile, the CTAB addition did not affect the Ce6 entrapment efficiency and physical attributes of the liposomes. In vitro studies showed that the PDI effect of the Ce6-loaded CTAB-liposomes was dependent on the lipid to Ce6 molar ratio (L/C), particle size and the concentration of CTAB in the liposomes. The lower L/C ratio and smaller liposomes exerted significantly higher PDI effects. In addition, an increase in the CTAB to lipid ratio led to a significant increase in the PDI effect of Ce6 against susceptible and drug-resistant clinical isolates of C. albicans after light illumination.
  
  
  CONCLUSIONS
  Our results indicate that a low L/C ratio, high positive charge, and small particle size of CTAB-liposomes significantly enhances their PDI efficacy against C. albicans.
authors.affiliation: Department of Biochemical Science and Technology, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Yu-Tsai
authors.initials: YT
authors.lastname: Yang
authors.forename: Hsiung-Fei
authors.initials: HF
authors.lastname: Chien
authors.forename: Po-Han
authors.initials: PH
authors.lastname: Chang
authors.forename: Yee-Chun
authors.initials: YC
authors.lastname: Chen
authors.forename: Michael
authors.initials: M
authors.lastname: Jay
authors.forename: Tsuimin
authors.initials: T
authors.lastname: Tsai
authors.forename: Chin-Tin
authors.initials: CT
authors.lastname: Chen
mesh_terms: D000818:Animals; D000891:Anti-Infective Agents, Local / Q000008:administration & dosage* / Q000627:therapeutic use; D002056:Burns / Q000150:complications; D002176:Candida albicans / Q000187:drug effects*; D002177:Candidiasis / Q000188:drug therapy* / Q000209:etiology; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000008:administration & dosage* / Q000627:therapeutic use; D002735:Chlorophyllides; D008081:Liposomes; D008297:Male; D008856:Microscopy, Fluorescence; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D011166:Porphyrins / Q000008:administration & dosage* / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D016896:Treatment Outcome
chemical_list: D000891:Anti-Infective Agents, Local; D002593:Cetrimonium Compounds; D002735:Chlorophyllides; D008081:Liposomes; D017319:Photosensitizing Agents; D011166:Porphyrins; C062985:phytochlorin; D000077286:Cetrimonium