Photodynamic properties and photoantimicrobial action of electropolymeric films composed of porphyrins

MATÍAS D. FUNES; DANIEL A. CAMINOS; M. GABRIELA ALVAREZ; FERNANDO FUNGO; LUIS A. OTERO; EDGARDO N. DURANTINI

Enviromental Science & Technology

American Chemical Society

Año: 2009 vol. 43 p. 902 - 908

Spectroscopic and photodynamic properties of polymericfilms bearing porphyrin units have been studied in both solutioncontaining photooxidizable substrates and in vitro onEscherichia coli and Candida albicans microorganisms. Thefilms were formed by electrochemical polymerization of5,10,15,20-tetra(4-N,N-diphenylaminophenyl)porphyrin (H2P-film)and its complex with Pd(II) (PdP-film) on optically transparentindium tin oxide (ITO) electrodes. Absorption spectroscopic studiesshow the characteristic Soret and Q bands of the porphyrinin the visible region and a band at ∼350 nm corresponding tothe tetraphenylbenzidine units. Upon excitation, the H2P-filmexhibits two bands of fluorescence emission from porphyrin,while it is not detected using PdP-film. The singlet molecularoxygen, O2(1Δg), productions of these surfaces were evaluatedusing 9,10-dimethylanthracene in N,N-dimethylformamide.Also, the photodynamic activity was compared in solutions ofL-tryptophan. Under these conditions, oxidation of thesesubstrates takes place indicating an efficient photodynamicaction of both polymeric films. In vitro investigations show thatthese films produce photosensitized inactivation of microbialcellsinaqueoussuspensions.Thesefilmsexhibitaphotosensitizingactivity causing a ∼3 log decrease of E. coli and ∼2.5 logof C. albicans cellular survival after 30 min of irradiation withvisible light. The photodynamic effect of the surfaces wasalso tested by growth delay experiments. The results indicatethat porphyrins immobilized on electropolymeric films areinteresting and versatile photodynamic surfaces to inactivatemicroorganisms in liquid suspensions.