Antimicrobial mechanisms behind photodynamic effect in the presence of hydrogen peroxide

Abstract

This study describes the use of methylene blue (MB) plus light (photodynamic inactivation, PDI) in the presence of hydrogen peroxide (H 2 O 2 ) to kill Staphylococcus aureus, Escherichia coli, and Candida albicans. When H 2 O 2 was added to MB plus light there was an increased antimicrobial effect, which could be due to a change in the type of ROS generated or increased microbial uptake of MB. To clarify the mechanism, the production of ROS was investigated in the presence and absence of H 2 O 2 . It was observed that ROS production was almost inhibited by the presence of H 2 O 2 when cells were not present. In addition, experiments using different sequence combinations of MB and H 2 O 2 were performed and MB optical properties inside the cell were analyzed. Spectroscopy experiments suggested that the amount of MB was higher inside the cells when H 2 O 2 was used before or simultaneously with PDI, and ROS formation inside C. albicans cells confirmed that ROS production is higher in the presence of H 2 O 2 . Moreover enzymatic reduction of MB by E. coli during photosensitizer uptake to the photochemically inactive leucoMB could be reversed by the oxidative effects of hydrogen peroxide, increasing ROS formation inside the microorganism. Therefore, the combination of a photosensitizer such as MB and H 2 O 2 is an interesting approach to improve PDI efficiency.

Influence of hydrogen peroxide or gold nanoparticles in protoporphyrin IX mediated antimicrobial photodynamic therapy on Staphylococcus aureus

“…The enhanced bacterial killing of PPIX-H 2 O 2 mixture may be explained as suggested by Funk and Krise (2007) which reported that H 2 O 2 may alter the membrane permeability and hence the probability of cellular accumulation of the PS, or it may be due to the fact that the photoreaction would cause membrane disruption which in turn facilitate the penetration of H 2 O 2 into the cell (Caetano et al, 2007). Seaver and Imlay (2011) suggested that higher effect of PDT in the presence of H 2 O 2 could be because PS has an easier transit across the bacterial cell membrane, or the presence of H 2 O 2 may increase the amount of molecular oxygen which improves the ROS formation as suggested by Garcez et al (2011). Narband et al (2008) reported the ability of GNPs to enhance the antimicrobial effectiveness of the PS, toluidine blue (TBO) against S. aureus when illuminated with light.…”

“…It is reported that, H 2 O 2 can be combined successfully in APDT to enhance the effecttiveness of the PS (McCullagh and Robertson, 2006). Garcez et al (2011) studied the antimicrobial photodynamic effect of methylene blue (MB) in the presence of H 2 O 2 to kill S. aureus, Escherichia coli and Candida albicans. They found that H 2 O 2 is an interesting approach to improve the antimicrobial effect of MB.…”

Photodynamic Therapy in Endodontics

“…In another study, Garcez et al 38 showed that endodontic treatment alone may produce a significant decrease in microbial count, whereas using the combination of endodontic treatment with PDT all teeth were bacteria-free. Garcez et al 39 also demonstrated that usage of PDT added to endodontic treatment of infected canals with the optical fiber may be better than when the laser is used directed at the cavity. Meire et al 40 compared the antimicrobial efficacy of neodymium-doped yttrium aluminum garnet (YAG), erbium-doped YAG (Er:YAG), two commercial antimicrobial PDT (aPDT) systems, and revealed that NaOCl is the most effective, while Er:YAG laser also resulted in high reductions of bacteria.…”

Photodynamic Therapy in the Treatment of Osteomyelitis

“…Adjuvants like hydrogen peroxide can increase the photodynamic efficiency by allowing better uptake of the photosensitizer [25]. Also, nanoparticle platforms have a great potential to control the mechanisms and efficiency of photodynamic action [26][27][28][29][30].…”

“…We and others have invested a lot of efforts on solving these issues related with PDT [6,[16][17][18][19][20][21][22][23][24][25]. New molecular structures, nanoparticles or nanoemulsions are being investigated in order to develop new and more efficient photo-active drugs [18][19][20][21][22][23][24][25][26][27][28][29][30]. Several medical conditions were treated by different protocols and depending on the medical condition, specific molecules and delivery systems were designed [5][6][7][8][9][10].…”