title: Photosensitization of Staphylococcus aureus with malachite green isothiocyanate: inactivation efficiency and spectroscopic analysis.
abstract: The potential of malachite green isothiocyanate as a photosensitizer for the inactivation of bacteria has been evaluated. Samples of Staphylococcus aureus are treated with the dye and exposed to continuous-wave red light from a filtered xenon lamp. Reduction in cell viability is seen to increase with radiation dose, whilst non-photosensitized samples are largely unaffected with exposure. The mechanism of photosensitization and the subsequent inactivation is addressed. UV-Vis and Fourier-transform infrared absorption spectrometry have been applied to this biological system, revealing the rapid hydrolysis of the isothiocyanate group of the dye and the transition to the colourless carbinol base when in solution. On binding to Staphylococcus aureus via a complexation mechanism, the dye is seen to be stabilized in its cationic form. Involvement of the excited triplet state of the photosensitizer is suggested and identification of reduced dye photoproducts is made following irradiation.
authors: Department of Physics and Astronomy, University of Manchester, UK. paul@fs4.ph.man.ac.uk
authors: P S
authors: PS
authors: Golding
authors: T A
authors: TA
authors: King
authors: L
authors: L
authors: Maddocks
authors: D B
authors: DB
authors: Drucker
authors: A S
authors: AS
authors: Blinkhorn
mesh_terms: D000042:Absorption; D015394:Molecular Structure; D010100:Oxygen / Q000502:physiology; D010787:Photosensitivity Disorders; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D012394:Rosaniline Dyes / Q000737:chemistry / Q000494:pharmacology*; D017550:Spectroscopy, Fourier Transform Infrared; D013211:Staphylococcus aureus / Q000187:drug effects*; D014466:Ultraviolet Rays
chemical_list: D017319:Photosensitizing Agents; D012394:Rosaniline Dyes; C005095:malachite green; D010100:Oxygen