Investigating the Effects of Commercial Antimicrobial Agents on Human Corneal Epithelial Cell Membranes
Poster Feb 27, 2015
Ian J. Horner, Jerod J. Hurst, Nadine D. Kraut, Alyssa A. Rook, Crystal M. Collado, G Ekin-Atilla Gokcumen, and Frank V. Bright
Multi-purpose solutions (MPS) are a single solution that functions to simultaneously rinse, disinfect, clean and store soft contact lenses. Several commercial MPS products contain polyhexamethylene biguanide (PHMB) and/or polyquaternium-1 (PQ-1) as antimicrobial agents. In this proster we report the effects of PHMB and PQ-1 on small unilamellar vesicles (SUV) that we have designed to mimic the average human corneal epithelial cell membrane. Specifically, we assessed the interactions of PHMB and PQ-1 on the biomembrane by using fluorescence spectroscopy, dynamic light scattering (DLS), and liquid chromatography/mass spectrometry (LC-MS). Fluorescence assessed the membrane surface polarity and stability through the temperature-dependent generalized polarization (GP), the gel-to-liquid transition temperature (Tm) and the associated van’t Hoff enthalpy (ΔHVH) as a function of PHMB and PQ-1 concentration. DLS evaluated SUV aggregation as a function of PHMB and PQ-1 concentration and SUV composition. LC-MS determined the composition of any precipitates that formed. PHMB association with the mimic SUV bilayer leads to: (i) a decrease in surface polarity, (ii) an increase in (Tm), (iii) an increase in phospholipid-phospholipid cooperativity, and (iv) an increase in SUV size on a nanometer scale. PQ-1 association with the mimic SUV bilayer leads to: (i) an increase in surface polarity (ii) no change in (Tm), (iii) no change in phospholipid-phospholipid cooperativity, and (iv) an increase in SUV size on a micron scale due to SUV aggregate formation. The aggregates exhibited a phospholipid composition equivalent to the SUV prior to the addition of PQ-1. These results are consistent with PHMB adsorbing onto and PQ-1 intercalating into the mimic SUV bilayer structures.