title: Characterization and optimization of mTHPP nanoparticles for photodynamic therapy of head and neck cancer.
abstract: OBJECTIVE
  To characterize the properties of polymeric micelles containing different loading percentages of mTHPP, a photosensitizer for photodynamic therapy (PDT), with respect to fluorescence, singlet oxygen ((1)O(2)) yield, and in vitro cytotoxicity in head and neck cancer cells.
  
  
  METHODS
  Laboratory study.
  
  
  METHODS
  Polymer chemistry laboratory.
  
  
  METHODS
  Absorption and emission spectroscopy was used to characterize the mTHPP-loaded micelles. The (1)O(2) yield was measured to determine the efficiency of reactive oxygen species (ROS) generation. In vitro studies were conducted using the HN5 cells and confirmed with H2009 cells to determine the photodynamic efficacy. DNA assay and confocal microscopy was used to measure intracellular fluorescence.
  
  
  RESULTS
  The mTHPP micelles demonstrated the highest fluorescence intensity at 0.5% loading. The (1)O(2) generation of the micelles in solution peaked at 2% loading. Phototoxicity and dark toxicity experiments in HN5 and H2009 cells demonstrated that the best therapeutic index was achieved with the 2% loaded micelles with 100% cell cytotoxicity at a micelle concentration of 10 µg/mL and less than 10% dark cytotoxicity. In comparison, 10% loaded micelles demonstrated 100% cell cytotoxicity at a concentration of 20 µg/mL under both light and dark conditions. Confocal microscopy demonstrated increasing intracellular fluorescence with higher loading.
  
  
  CONCLUSIONS
  The 2% mTHPP-loaded micelles generated greater (1)O(2), and 0.5% loading led to the most efficient generation of fluorescence in solution. Higher mTHPP loading density led to increased cellular fluorescence and dark cytotoxicity. Overall, 2% mTHPP-loaded micelles provided the optimal composition for photodynamic therapy with the largest therapeutic window.
authors: Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA.
authors: Huiying
authors: H
authors: Ding
authors: Ruben
authors: R
authors: Mora
authors: Jinming
authors: J
authors: Gao
authors: Baran D
authors: BD
authors: Sumer
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000188:drug therapy*; D008823:Micelles; D018613:Microscopy, Confocal; D053758:Nanoparticles; D016877:Oxidants / Q000378:metabolism; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D011166:Porphyrins / Q000008:administration & dosage*; D026082:Singlet Oxygen / Q000378:metabolism; D013057:Spectrum Analysis; D014407:Tumor Cells, Cultured
chemical_list: D008823:Micelles; D016877:Oxidants; D017319:Photosensitizing Agents; D011166:Porphyrins; C437342:tetra(3-hydroxyphenyl)porphine; D026082:Singlet Oxygen