Faculty of Physics - University of Bucharest

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FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2014 Meeting

Section: Optics, Spectroscopy, Plasma and Lasers

Title:

Spectroscopic and optical studies of antibiotic foams generated by laser irradiation

Authors:

Andra DINACHE(1), M.BONI(1,2), Angela STAICU(1), Tatiana ALEXANDRU(1,2), V. NASTASA(1), A.STOICU(1), I.R.ANDREI(1), V.DAMIAN(1), M.L.Pascu(1,2)

Affiliation:

1) National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania

2) Faculty of Physics, University of Bucharest, Magurele, Romania

E-mail

andra.dinache@inflpr.ro

Keywords:

foam, Vancomycin, laser irradiation, spectroscopy

Abstract:

Foams have complex properties which make them suitable for a number of applications, industrial processes included. In medical applications foams are used in sclerotherapy and may also serve as models for biological tissues. If a Vancomycin (a highly toxic antibiotic) solution in ultrapure de-ionized water is exposed to laser radiation, foam may be generated in specific experimental conditions. This foam contains Vancomycin (VCM) molecules and/or photoproducts generated by the interaction of the VCM and solvent molecules with the laser radiation. The exposure of VCM was made using a pulsed laser beam emitted as the fourth harmonic of a Nd:YAG laser fascicle (λ=266nm), the average beam energy varying within the interval 1–40mJ. The exposure time was chosen function of several parameters such as: volume of the solution, laser beam characteristics (energy, focus waist and place, beam divergence) and irradiation geometry. The UV-Vis absorption and FTIR spectra of VCM solutions recorded before and after exposure to laser beams were employed to detect the modification of VCM molecules and the formation of photoproducts that appear during/as a consequence of the irradiation. Surface tension of a droplet containing VCM solution was measured before and after irradiation. The laser induced fluorescence (LIF) spectra yielded real-time information about the modifications of VCM molecules while exposing the medicines solutions to the laser beam. Optical microscopy was employed to characterize the dimensions of the gas bubbles in the VCM foams. Foams generation in VCM solutions during laser irradiation requires a bubble nucleation, most probably generated by the transient acoustic waves induced by the laser pulse. The foam produces modifications of the VCM molecules, especially to the tyrosine radicals in the glycopeptide, as indicated by the absorption spectra. Acknowledgements: The authors acknowledge the financial support of project number PN-II-ID-PCE-2011-3-0922, MEN-CDI Nucleu project: PN0939/2009 and COST Action MP1106.