title: Photokinetic Drug Delivery: Light-Enhanced Permeation in an In Vitro Eye Model.
abstract: OBJECTIVE
  To investigate light-enhanced molecular movement as a potential technology for drug delivery. To do this, we developed an in vitro eye model while representing similar concentration gradient conditions and compositions found in the eye.
  
  
  METHODS
  The eye model unit was fabricated by inserting a cross-linked type I collagen membrane in a spectrophotometer cuvette with 1% hyaluronic acid as the drug recipient medium. Photokinetic delivery was studied by illuminating 1 mg/mL methotrexate (MTX) placed in the drug donor compartment on top of the membrane, with noncoherent 450 nm light at 8.2 mW from an LED source pulsed at 25 cycles per second, placed in contact with the solution. A modified UV-visual spectrophotometer was employed to rapidly determine the concentration of MTX, at progressive 1 mm distances away from the membrane, within the viscous recipient medium of the model eye after 1 h.
  
  
  RESULTS
  A defined, progressive concentration gradient was observed within the nonagitated drug recipient media, diminishing with greater distances from the membrane. Transport of MTX through the membrane was significantly enhanced (ranging from 2 to 3 times, P < 0.05 to P ≤ 0.001) by photokinetic methods compared with control conditions by determining drug concentrations at 4 defined distances from the membrane. According to scanning electron microscopy images, no structural damage or shunts were created on the surface of the cross-linked gelatin membrane.
  
  
  CONCLUSIONS
  The application of pulsed noncoherent visible light significantly enhances the permeation of MTX through a cross-linked collagen membrane and hyaluronic acid recipient medium without causing structural damage to the membrane.
authors: 1 Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch , Galveston, Texas.
authors: Bernard F
authors: BF
authors: Godley
authors: 1 Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch , Galveston, Texas.
authors: Edward R
authors: ER
authors: Kraft
authors: 1 Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch , Galveston, Texas.
authors: Steven A
authors: SA
authors: Giannos
authors: 1 Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch , Galveston, Texas.
authors: Zhen-Yang
authors: ZY
authors: Zhao
authors: 2 Biomolecular Resource Facility, University of Texas Medical Branch , Galveston, Texas.
authors: Anthony M
authors: AM
authors: Haag
authors: 3 Electron Microscopy Laboratory, University of Texas Medical Branch , Galveston, Texas.
authors: Julie W
authors: JW
authors: Wen
mesh_terms: D001692:Biological Transport; D024042:Collagen Type I / Q000378:metabolism; D016503:Drug Delivery Systems; D005123:Eye / Q000378:metabolism*; D005780:Gelatin / Q000378:metabolism; D006820:Hyaluronic Acid / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D007700:Kinetics; D008027:Light; D008727:Methotrexate / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008855:Microscopy, Electron, Scanning; D010539:Permeability; D010777:Photochemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D024042:Collagen Type I; D007166:Immunosuppressive Agents; D005780:Gelatin; D006820:Hyaluronic Acid; D008727:Methotrexate