Protoporphyrin IX-loaded magnetoliposomes as a potential drug delivery system for photodynamic therapy: Fabrication, characterization and in vitro study

Background: Protoporphyrin IX (PpIX) is a well-known photosensitizer that has great potential for use in photodynamic therapy (PDT). However, aggregation behavior of PpIX in neutral water makes it inappropriate for physiological studies. PpIX-loaded magnetoliposomes (MLs) were fabricated to increase PpIX biocompatibility. PpIX-loaded ML physical properties were characterized, and PpIX-loaded ML drug release behavior was investigated under the influence of an external magnetic field and heat. Toxicity and photodynamic effects of the complex were also examined using in vitro experiments with MCF-7 human breast cancer cells. Methods: The magnetoliposomes were prepared with DPPC, DSPE-PEG2000 lipids and Fe3O4 nanoparticles. The toxicity and in vitro photodynamic effects of the PpIX-loaded MLs at various concentrations were studied using the MCF-7 cell line. Results: The produced PpIX-loaded MLs exhibited an average hydrodynamic diameter of 221 nm; however, TEM measurements indicated that the diameter of the PpIX-loaded MLs varied between 166 and 720 nm. The iron content of the MLs affected cell viability less than the content of the iron free liposomes. Cell viability was reduced to 66% when the concentration of the PpIX-loaded MLs was 350 nM, but when white light was applied for 5 min, all of the cells that were exposed to concentrations of 250 nM and higher PpIX died within 24 h. Conclusion: The results of this study demonstrated the effective application of PpIX-loaded MLs for in vitro photodynamic therapy at nanomolar concentrations. The results also indicated that an LED light source provided sufficient energy to stimulate the PpIX molecules. (C) 2015 Elsevier B.V. All rights reserved.