Photodynamic Properties and Photoantimicrobial Action of Electrochemically Generated Porphyrin Polymeric Films

Abstract

Spectroscopic and photodynamic properties of polymeric films bearing porphyrin units have been studied in both solution containing photooxidizable substrates and in vitro on Escherichia coli and Candida albicans microorganisms. The films were formed by electrochemical polymerization of 5,10,15,20-tetra(4-N,N-diphenylaminophenyl)porphyrin (H2P-film) and its complex with Pd(II) (PdP-film) on optically transparent indium tin oxide (ITO) electrodes. Absorption spectroscopic studies show the characteristic Soret and Q bands of the porphyrin in the visible region and a band at approximately 350 nm corresponding to the tetraphenylbenzidine units. Upon excitation, the H2P-film exhibits two bands of fluorescence emission from porphyrin, while it is not detected using PdP-film. The singlet molecular oxygen, O2(1Deltag), productions of these surfaces were evaluated using 9,10-dimethylanthracene in N,N-dimethylformamide. Also, the photodynamic activity was compared in solutions of L-tryptophan. Under these conditions, oxidation of these substrates takes place indicating an efficient photodynamic action of both polymeric films. In vitro investigations show that these films produce photosensitized inactivation of microbial cells in aqueous suspensions. These films exhibit a photosensitizing activity causing a approximately 3 log decrease of E. coil and approximately 2.5 log of C. albicans cellular survival after 30 min of irradiation with visible light. The photodynamic effect of the surfaces was also tested by growth delay experiments. The results indicate that porphyrins immobilized on electropolymeric films are interesting and versatile photodynamic surfaces to inactivate microorganisms in liquid suspensions.

Potential applications of porphyrins in photodynamic inactivation beyond the medical scope

“…They caused a photosensitizing activity of ≈2.5 log decrease of C. albicans survival after 60 min of irradiation (324 J cm −2 ) [61]. Comparatively to the results obtained by Funes et al [63], the main difference of the present SSO-PS films is their versatility as plastic flexible materials at room temperature, easy to obtain and ability to shape the surfaces. They also keep a higher antifungal activity against C. albicans.…”

“…The efficient photodynamic effect of other photoactive surfaces was demonstrated by Funes et al [63] The authors used two polymeric porphyrinated films formed by electrochemical polymerization of free-base 5,10,15,20-tetrakis(4-(N,N-diphenyl)aminophenyl)porphyrin (Tetra-N,N-DiPh-film) and its complex with Pd(II) (Pd(II)Tetra-N,N-DiPh-film) on optically transparent indium tin oxide (ITO) electrodes on microbial cell suspensions. The polymeric surfaces (0.7 × 3.0 × 2.1 cm 2 ) were placed inside of E. coli and Candida albicans suspensions (≈10 6 CFU mL −1 ) and irradiated with visible light (90 mW cm −2 ) for different time periods.…”

“…No [47] No [50,52,69] On filter paper [82] On cotton fabric [86,108] On polysilsesquioxane plastic films [61] On cotton fabric [87] On azide-modified cellulose nanocrystals [43,75] On chloroacetyl cellulose ester chlorides [78] On cellulose laurate esters plastic films [79] No [71] No [93] No [49,71,93,110] and Tri-Py + -Me-PF on silica coated Fe3O4 nanoparticles [70] and also on CoFe2O4 nanoparticles [111] No [81] No [105] No [36,37,71,74,81,105]; Tetra-Py + -Me was entrapped into microporous silica gels [88] and into three alkylene-bridged polysilsesquioxanes [89] On optically transparent indium tin oxide electrodes [63] On chitosan membranes [72] Pd(II) TetraTPPCO2H On a polyurethane matrix [83] No [105] In hydrophilic polycaprolactone and polyurethane (TecophilicH) nanofibers [60]; on electrospun polymeric nanofiber materials polyurethane Larithane TM , polystyrene, polycaprolactone, and polyamide 6 [76]; into three alkylene-bridged polysilsesquioxanes [89]; and in a silica-gel supported antimony porphyrin complex SbTPP [97,98] No [44,…”

“…Both Tetra-N,N-DiPh-and Pd(II)Tetra-N,N-DiPh-films exhibited a photosensitizing activity causing a ≈3 log decrease of E. coli survival after 30 min of irradiation and a ≈2 log decrease in C. albicans viability. The advantages of these electrodes are that they represent an appropriated surface to obtain mechanically stable electropolymeric films, they are optically transparent to visible light, and also that they can be easily and quickly removed from the media after cell inactivation, avoiding permanent photodynamic effects [63].…”

Photodynamic therapy based on 5‐aminolevulinic acid and its use as an antimicrobial Agent

“…Based on this antimicrobial capability, PDT has been extensively investigated for use in the clinical arena to treat local infections such as those of the oral cavity or the skin . However, the technique has also been applied to a number of nonclinical uses, which include: blood decontamination, the production of anti‐infective medical devices and surfaces, water disinfection, and pathogen inactivation in fish farming …”